Showing papers in "International Journal of Cancer in 1975"

Environmental factors and cancer incidence and mortality in different countries, with special reference to dietary practices

Abstract: Incidence rates for 27 cancers in 23 countries and mortality rates for 14 cancers in 32 countries have been correlated with a wide range of dietary and other variables. Dietary variables were strongly correlated with several types of cancer, particularly meat consumption with cancer of the colon and fat consumption with cancers of the breast and corpus uteri. The data suggest a possible role for dietary factors in modifying the development of cancer at a number of other sites. The usefulness and limitations of the method are discussed.

Natural cytotoxic reactivity of mouse lymphoid cells against syngeneic and allogeneic tumors. I. Distribution of reactivity and specificity

Abstract: Lymphoid cells from many normal mice of a variety of inbred strains were found to have reactivity, in a 51Cr release cytotoxicity assay, against several syngeneic and allogeneic tumors. Very high reactivity was seen with effector cells from athymic nude mice, which was consistent with other evidence that the reactivity was not T-cell dependent. Target cells susceptible to lysis included tumors induced by oncogenic type-C viruses but also tumors induced by other means and expressing endogenous type-C viruses. The levels of natural reactivity were influenced by age, with highest cytotoxicity produced by cells from 5- to 8-week-old mice. Lymph-node cells, spleen cells, peritoneal exudate cells and peripheral blood lymphocytes all had cytotoxic reactivity. The specificity of the reactions was analyzed in detail by ana inhibition assay. Evidence was obtained for natural reactivty against several different antigens, each apparently associated with expression of murine endogenous type-C viruses.

Natural cytotoxic reactivity of mouse lymphoid cells against syngeneic and allogeneic tumors. II. Characterization of effector cells

Abstract: Studies were performed to characterize the effector cells responsible for natural cytotoxicity of mouse lymphoid cells against a variety of syngeneic and allogeneic tumor lines. Since spleen cells from normal nude mice were found to be highly cytotoxic, they were used for most of these experiments. Only a small proportion of the reactivity was affected by treatment with anti-theta serum plus complement. Macrophages dis not appear to be responsible for the reactivity, since treatment with carbonyl iron/magnet or carrageenan did not affect the levels of cytotoxicity. The effector cells were non-adherent, since passage over nylon columns resulted in a considerable increase in activity. The active cells did not have receptors for immunoglobulin or complement, since removal of cells with these receptors by columns or monolayers containing sheep erythrocyte-antibody (EA) complexes or EA-complement complexes did not remove activity. Antibody-dependent cell-mediated cytotoxicity appeared to be ruled out as the mechanism for natural cytotoxicity, since aggregated gamma globulin and a potent anti-immunoglobulin reagent did not inhibit reactivity, and since no role for humoral factors could be demonstrated. The natural effector cell was found to be quite labile at 37 degrees C, losing much of its activity after 4 h. Since no surface markers could be detected on the effector cells, and the mechanism for cytotoxicity appeared distince from others previously described, it is proposed that the natural cytotoxicity against mouse tumor cells is mediated by a unique subpopulation of lymphoid cells, which are tentatively designated N-cells.

Establishment of a continuous tumor‐cell line (PANC‐1) from a human carcinoma of the exocrine pancreas

Abstract: An epithelioid cell line, started from a human pancreatic carcinoma of ductal cell origin, has been maintained in culture for over 2 years and has been subcultured more than 40 times. The PANC-1 cell line has a doubling time of 52 h and G6PD activity of the slow mobility of B type. Chromosome studies show a modal number of 63 with three distinct marker chromosomes and a small ring chromosome. The malignant nature of the PANC-1 cell line was verified by: (1) the ready growth of PANC-1 cells in soft agar and on top of a fibroblast monolayer; and (2) the formation of a progressively growing anaplastic carcinoma after injection of a nude-athymic mouse with PANC-1 cells.

Dietary vitamin A and human lung cancer.

Abstract: Five-year follow-up results for 8,278 men who in mail surveys had reported their cigarette smoking and dietary habits showed: (1) an index for vitamin A intake to be negatively associated with lung cancer incidence at all levels of cigarette smoking;(2) this association to be more clearly expressed in the subset of histologically proven pulmonary carcinomas other than adenocarcinoma; and (3) the positive association between cigarette smoking and lung cancer to obtain irrespective of the dietary level of vitamin A or related factors. The findings are in accordance with experimental results on animals and call for further exploration of the role of nutritional factors in the development of human lung cancer.

Classification and biological nature of established human hematopoietic cell lines

Abstract: Over 200 established human hematopoietic cell lines of normal and malignant origin have been investigated by morphological and functional parameters. Employing morphology as the overriding parameter four types of lines were identified. (1) Lymphoblastoid cell lines, derived from normal and neoplastic hematopoietic tissue, were characterized by the wide morphologic flexibility of individual lymphoblastoid cells, constant association with Epstein-Barr virus (EBV), polyclonal derivation, differentiation for immunoglobulin production (secretion) and their diploids. (2) Lymphoma cell lines. This type of line was established at a high frequency from Burkitt's lymphoma and rarely from other types of lymphoma, but never from patients without malignancy or with non-lymphoma malignancies. Important characteristics were morphologic stereotypia within each line, monoclonal derivation, common but not obligatory association with EBV, variability in the expression of Ig synthesis (no production, or membrane bound Ig, or secretion) and aneuploidy. (3) Myeloma cell lines could only rarely be obtained from patients with myeloma. The basis for classification of these lines is their production of Ig identical to the myeloma protein in vitro. Other important distinguishing features were: plasma cell morphology, absence of EBV and aneuploidy. (4) The leukemia cell line (MOLT 4) was the only line with T-cell characteristics and was easily distinguished from the other types. Important characteristics were a typical surface ultrastructure, absence of EBV and absence of immunoglobulin production, Individual lymphoblastoid lines were in principle identical whereas each line of the other three types had its own characteristic profile. The phenotypic characteristics of the lymphoblastoid lines were very stable during prolonged serial cultivation. Only in a few cases were secondary chromosomal, functional or morphologic alterations noted. We conclude that EBV-carrying lymphoblastoid lines can be obtained from non-neoplastic precursor cells from healthy as well as from diseased individuals. Lymphoma, myeloma and leukemia lines are only obtained from the respective neoplastic tissue but generally at a low frequency. With the exception of Burkitt's lymphoma, malignant hematopoietic tissue and leukemia frequently give rise to established cell lines in vitro of the lymphoblastoid type rather than lines derived from the neoplastic cells;

Rat cell line 3y1 and its virogenic polyoma- and sv40- transformed derivatives.

Abstract: Cell lines were established from cultures derived from Fischer rat embryos according to the transfer schedule described by Todaro and Green (1963) for mouse 3T3 cells where cell crowding and serum exhaustion were kept to a minimum. Cell growth rate did not decline greatly during the course of successive 3-day transfers. Like 3T3 cells, the rat cell lines possess very low saturation densities under standard culture conditions. A clonal cell line with a relatively high plating efficiency was obtained from one of the cell lines, 3Y1. In these cloned cultures, virus growth was not detectable upon infection with SV40, while a small amount of virus was produced upon infection with polyoma virus. Morphological transformation of the cloned 3Y1 cells by SV40 and polyoma virus could be assayed with single-hit kinetics and with efficiencies comparable to those of the previously available transformation systems for each virus. Independent cell lines transformed by SV40 were consistently virus-free and all the lines tested produced SV40 upon fusion with permissive monkey cells. Most of the independent transformed cell lines isolated after polyoma infection appeared to be virus-free, although the cultures of some lines produced a small amount of polyoma virus spontaneously after a prolonged cultivation. Most of the virus-free polyoma-transformed lines produced virus upon fusion with permissive mouse cells.

Surface Markers on Human B and T Lymphocytes. VI. Cytotoxicity Against Cell Lines as a Functional Marker for Lymphocyte Subpopulations

Abstract: The spontaneous lymphocyte mediated cytotoxicity (SLMC) of cells from normal donors against 19 different established cell lines was analysed. All normal lymphocytes were cytotoxic in all combinations tested in a17h 51-Cr release assay. ALMC was found to be mediated by a minor subpopulation of lymphocytes with Fc/C3 receptors. Non-cytotoxic SRBC binding T-lymphocytes could be induced to become cytotoxic by the addition of Con A to the incubation medium. SLMC and lectin-induced cytotoxicity were briefly characterized. It is argued that SLMC is a non-specific non-immunological reaction which must be taken into consideration when lymphocytes from cancer patients are tested against tumour-cell lines in vitro. Futhermore, SLMC and letin-induced cytotoxicity are proposed as functional markers for Fc/C3-binding lymphocytes and SRBC binding lymphocytes respectively.

Genetic variation of in vitro cytolytic activity and in vivo rejection potential of non-immunized semi-syngeneic mice against a mouse lymphoma line.

Abstract: Spleens of normal young mice of certain genotypes contain lymphocytes that can kill strain A-derived YAC-1 and some other in vitro-grown Moloney lymphoma lines in a 51Cr-release cytotoxic test. We have previously shown that mouse strains can be classified as high or low reactors in this test. F(1) hybrids between low- and high-reactive strains are high-reactive. In the present study, strain-A mice and eight different A F(1) hybrids were tested in parallel for their spleen-cell-mediated killing effect in vitro and their ability to reject graded numbers of YAC ascites or in vitro cultivated cells in vivo. There was a clear correlation between in vitro cytotoxicity and in vivo rejection in all tested genotypes. In segregating (A times C57Bl) times A backcross mice, in vivo rejection of YAC cells was H-2 linked. This is in line with the earlier backcross analysis of the in vitro cytotoxicity, suggesting a polygenic control with at least one H-2 linked factor.

Antibody patterns to herpesviruses in Kaposi's sarcoma. II. Serological association of American Kaposi's sarcoma with cytomegalovirus.

Abstract: The prominent finding of this extended serologic analysis on American and African Kaposi's sarcoma (KS) patients and appropriately matched control groups is the detection of a specific serologic association of cytomegalovirus (CMV) with American KS patients. All American KS sera contained CMV antibodies and their geometric mean titers (GMT) were significantly higher than those in sera of melanoma patients (GMT ratio k = 5.3 to 7.7 by complement fixation [CF], k = 8.9 by indirect hemagglutination [IHA]) or in sera of age- and sex-matched healthy controls (k = 12.6 to 16.0 by CF, k = 12.6 by IHA). The result is strongly reminiscent of the data obtained previously for European KS. Although the GMT to CMV of African KS patients were similar to the GMT of the American KS groups, their significance cannot be demonstrated due to the high background of CMV infections in the control groups. Complex mechanisms are hypothesized, by analogy with the Epstein-Barr virus (EBV) involvement in Burkitt's lymphoma (BL), for a CMV involvement in the development of KS.

Non-producer human cells induced by murine sarcoma virus.

Abstract: Non-produces (NP) human cells were isolated from transformed foci induced by the Kirsten mouse sarcoma virus. These morphologically altered NP cells produced neither infectious virus nor complement-fixing antigens of the murine sarcoma-leukemia virus complex. However, the sarcoma virus genome could be rescued from these NF cells by co-cultivation with cells carrying "helper" Kirsten mouse leukemia virus or Woolly Monkey leukemia virus. The possible usefulness of these cells in efforts designed to detect covert or repressed RNA tumor viruses in various animal and human tissues is discussed.

Human, rat and mouse liver-mediated mutagenicity of vinyl chloride in S. typhimurium strains.

Abstract: Exposure of S. typhimurium strains TA 1530, TA 1535 and G-46 to vinyl chloride increased the number of His+ revertants/plate 16, 12 or 5 times over the spontaneous mutation rate. After 6 h of exposure to vinyl chloride, the mutagenic response for TA 1530 strain was enhanced 7-, 4- or 5-fold when fortified postmitochondrial liver fractions from humans, rats or mice were added. The enzyme-mediated vinyl chloride mutagenicity was dependent on an NADPH generating system and the enzyme activity was localized in a liver microsomal fraction; 9,000 times g liver supernatant was three times more active than microsomes, while liver cytosol or alcohol dehydrogenase did not affect the mutagenicity. Phenobarbitone pretreatment of rats and mice increased the mutagenic response by up to 15-40 percent as compared to untreated controls. The relative mutagenic activities of VCM, taking the value from mouse liver as 100, for TA 1530 strain mediated by 9,000 times g tissue fractions were: rat liver, 80; mouse and rat kidney, 20 and 16; mouse and rat lung, less than 7; human liver (from four biopsy specimens) 170, 64, 70 and 46. Chloroacetaldehyde and chloroacetic acid, a urinary metabolite of VCM, showed toxic effects, while chloroethanol was weakly mutagenic for TA 1530 strain.

DNA repair synthesis of cultured human cells as a rapid bioassay for chemical carcinogens.

Abstract: The feasibility of detection of carcinogenic chemicals using DNA repair synthesis of cultured human fibroblasts as measured by an unscheduled 3HTdR incorporation has been explored Of 64 chemicals tested, 29 were proximate or ultimate carcinogens, 15 were precarcinogens that required metabolic activation, 16 were non-oncogenic compounds and 4 were of unknown carcinogenicity All directly acting carcinogens triggered a DNA repair synthesis, whereas no unscheduled 3HTdR incorporation was observed following the application of the 16 non-oncogenic compounds As a rule, the precarcinogens (without metabolic activation) do not elicit DNA repair synthesis However, longer exposures and higher concentrations of the precarcinogens 2-AAF, aflatoxin B1 and sterigmatocystin gave unscheduled 3HTdR uptake The results suggest the suitability of using repair synthesis as endpoint, and cultured human cells as subjects in a prescreening programme for chemical carcinogens

Nasopharyngeal carcinoma. X. Presence of epstein-barr genomes in separated epithelial cells of tumours in patients from Singapore, Tunisia and Kenya.

Abstract: Nasopharyngeal carcinoma (NPC) biopsies from Singapore, Tunisia and Kenya were compared, before and after separation of epithelial and lymphoid cells, for their EBV-DNA content, using the cellular DNA-EBV-cRNA hybridization test. In all instances where successful separation of the two cell types was achieved, epithelial tumour cells showed a higher EBV-DNA content than lymphoid cells or tumour before cell separation. It is, therefore, suggested that EBV-DNA is mostly limited to epithelial cells. No significant difference was observed between NPC tumours originating from various geographical areas.

A case/control study of the association between primary liver cancer and hepatitis B infection in Senegal.

Abstract: A case/control study has been carried out to determine by radioimmunoassay and passive hemagglutination techniques the prevalance of hepatitis B surface antigen (HBsAg) and antibody (anti-HBs) in patients with primary liver cancer (PLC) and age/sex-matched hospital controls with cancers of other sites (OCC) and similarly matched controls without cancer (NCC) HBsAg was found in 612% of 165 cases of PLC as compared to 117% of 154 OCC and 113% of 328 NCC The frequency of HBsAg in PLC patients was significantly higher (722%) in those with detectable alpha fetoprotein as compared to those without (403%) There was no difference in the frequency of HBsAg in PLC patients with and without accompanying cirrhosis No significant difference in potential hepatitis exposure history was found in the three study groups

Induction of specific changes in the surface membrane of myeloid leukemic cells by steroid hormones.

Abstract: Normal mature macrophages and granulocytes have surface membrane receptors for specific immunoglobulin and immunoglobulin complement, which can be detected by rosette formation with erythrocytes coated with antibody (EA) or with antibody and complement (EAC). There are three types of myeloid leukemia cells, IR-+D-+, IR-+D-minus and IR-minus D-minus. IR-+D-+ cells were induced to form receptors for EAC but not- for EA by the steroid hormones prednisolone, dexamethasone and estradiol. Induction required protein synthesis and was not inhibited by cordycepin or vinblastine. Optimum induction required the continued presence of the hormones. IR-+D-+ cells were also induced by these hormones to migrate in agar, attach to the surface of a Petri dish and form macrophages. IR-+D-minus cells showed a lower inducibility by these hormones and no formation of macrophages. There was no induction of any of these changes with IR-minusD-minus cells. The steroid hormones progesterone, testosterone and cortisone did not induce these changes in any of the leukemic cells and inhibited induction by prednisolone, dexamethasone and estradiol. The results indicate that specific surface membrane changes in myeloid leukemic cells can be induced by certain steroid hormones.

Studies on the role of macrophages in regulation of growth and metastasis of murine chemically induced fibrosarcomas

Abstract: Murine solid tumors were shown to contain 9-54% medium to large non-malignant cells bearing receptors for immunoglobulin Fc. These cells rapidly adhered to plastic surfaces, were trypsin-resistant, were capable of phagocytosis of latex particles and were sensitive to the lytic effects of anti-macrophage serum and complement. Purified Fc-receptor-positive cells failed to produce tumors, which strongly suggested that they were macrophages. When tumor-cell suspensions, depleted of macrophages by adherence to plastic surfaces, were injected subcutaneously into normal syngeneic mice, the tumors displayed an increased potential for metastasis. By contrast, control animals which received tumor-cell suspensions containing their normal complement of macrophages invariably developed progressive localized tumors. The survival times of mice infected with macrophage-depleted tumor-cell suspensions were significantly shorter (p less than 0.05) than those for animals inoculated with intact tumor-cell suspensions. These studies confirm the existence of a substantial number of macrophages within progressing syngeneic murine solid tumors and strongly suggest a regulatory role for the macrophages in the growth and metastasis of the tumor.

Specificity of cell-mediated cytotoxicity against human melanoma lines: evidence for "non-specific" killing by activated T-cells.

Abstract: The specificity of cell-mediated cytotoxicity against melanoma cells in vitro has been analyzed in a large number of studies with cells both from normal and melanoma subjects. As in a number of other, recent, similar human studies, no evidence for tumour specificity was found. Effector cells in peripheral blood responsible for the cytotoxic raction were examined by cell separation methods based on red cell rosette formation and separation through Hypaque-Ficoll mixtures. The evidence suggests that non-specificity results from killing by cells separating largely in the non-sheep red blood cell rosetting fraction and which have cytotoxic specificity directed broadly to cells with abnormal membranes. Further analysis revealed that the cells were non-phagocytic and did not bear receptors for complement. They appear to be activated into cell division and to bear surface receptors for the Fc portion of IgG. Additional evidence is presented suggesting that the cells mainly responsible are activated thymus-dependent cells present in the circulation of both tumour-bearing and normal subjects.

Erythropoietin-independent erythroid colony formation in vitro by hemopoietic cells of mice infected with friend virus.

Abstract: We have investigated the production of erythroid colonies in plasma culture by bone-marrow and spleen cells taken form C3Hf/Bi mice previously infected with a polycythemic strain of Friend virus (FV). Inclusion of erythropoietin (Epo) in the medium was found unnecessary for erythroid colony formation in vitro by these cells, although it was essential for the production of erythroid colonies by hemopoietic cells from normal animals. Development of erythroid colonies also proceeded umimpeded when cells from FV-infected animals were cultivated in medium pretreated with rabbit anti-serum that was shown to inactivate Epo. Thus, the hemopoietic tissues of FV-infected mice contained erythroid colony-forming units (CFU-Es) which appeared to be Epo-independent. When spleen cells from FV-infected mice were exposed to antiserum directed against syngeneic FV-infected spleen cells and complement, and then cultured with or without Epo, the number of erythroid colonies that developed was drastically reduced, indicating that the CFU-Es in these animals carried FV-induced antigen(s), and must themselves have been infected with virus. Electron microscopy of erythroid colonies produced by cells from FV-infected mice revealed the presence of budding and abundant free type-C virus particles. The efficiency of erythroid colony formation in vitro either with or without Epo by hemopoietic cells from FV-infected mice was substantially increased over that of cells from normal mice. The increase in the number of CFU-Es in these animals was due mainly to an increase in the number of Epo-independent CFU-Es. Epo-independent CFU-Es were first detected in bone marrow and spleen as early as 3 days after FV infection; thereafter their numbers progressively increased for at least 9 days. Hypertransfusion with red blood cells prior to FV infection reduced, while bleeding greatly increased, the efficiency of erythoid colony formation without Epo by cells from the spleens of the infected mice. The phenomenon of erythroid colony formation in plasma cultures lacking Epo provides a sensitive and reliable means of detecting Epo-independent CFU-Es, which appear to play a fundamental part in pathogenesis of the disease resulting from infection with the polycythemic strain of FV.

Enhancement by drugs of metastatic lung nodule formation after intravenous tumour cell injection.

Abstract: In studies on a model of induced pulmonary metastasis in mice a tumour host system was analysed which was not affected by immunogenicity of the tumour for the host; neither intensive immunosuppression nor immunization caused a significant change in the quantity of pulmonary metastatic nodules. In contrast the application of cytostatic drugs and of Corynebacterium parvum could modify the pulmonary resistance to the formation of tumour nodules by a factor greater than 100 in either direction. This finding confirms the observation of others that major modification of the resistance to metastatic tumour formation can occur independently of classical immunological mechanisms. Special attention is drawn to the fact that cyclophosphamide enhances the formation of metastatic nodules in this model by factors of 100 to more than 1,000, whereas other cytostatic drugs include the cyclophosphamide congeners iphosphamide and trophosphamide are active only by factors between 2 and 12. The possible practical significance of these findings is discussed. Chemicals/CAS: cyclophosphamide, 50-18-0; ifosfamide, 3778-73-2; trofosfamide, 22089-22-1; Alkylating Agents; Antineoplastic Agents; Busulfan, 55-98-1; Globulins; Mitolactol, 10318-26-0; Nitrogen Mustard Compounds

Prostaglandin synthesis inhibition: Effect on bone changes and sarcoma tumor induction in balb/c mice

Abstract: An increase in prostaglandins (PGs) of the E series has been demonstrated in Moloney sarcoma virus (MSV)-induced leg tumors of 6-week-old BALB/c male mice. The level of the hormone has been shown to increase with the tumor diameter and decrease with tumor regression. At the peak of tumor size the tibial bones of the mice were considerably deformed, suggesting osteoclastic activity. The systemic calcium level was not elevated, indicating possible release of calcium into the local tumorous area. In mice treated with indomethacin the tumors failed to develop and PG levels were markedly lower. Tibial bones of treated mice were similar in appearance to those of control, non-tumorous mice. PG levels of DBA/1J mice bearing extensive Cloudaman S91 melanomas were not elevated and no bone deformation was seen. When contrasted with studies of immuno-depressed mice the results suggest that indomethacin acted in conjunction with and possibly to restore the PG-induced depression of the immune system in preventing tumor development. It is also hypothesized that indomethacin, by suppressing the PG-mediated calcium release from bone, could be operative in inhibiting tumor growth.

Studies of genetic transmission of mammary tumour virus by C3Hf mice.

Abstract: By radioimmunoassay (RIA) mammary tumour virus (MTV) antigens were detected in individual milk samples of C3Hf mice, (female BALB/c X male C3Hf)F1 mice and (female C3Hf X male BALB/c)F1 mice; milk samples of BALB/c mice were negative. In the segregating backcross I population, female BALB/c X male (female BALB/c X male C3Hf) viral antigens were found in the milk of 93 out of 169 mice (55%). In the Bc II population (daughters of Bc I mothers and BALB/c fathers) two groups were distinguished. In the first group, derived from positive Bc I mothers, 55 out of 110 mice (50%) had detectable levels of viral antigens in the milk. In the second group, progeny of negative Bc I mothers, 1 mouse out of 47 was positive. These data are consistent with the assumption that one dominant gene is responsible for the presence of viral antigens in the milk of C3Hf mice. This gene (Mtv-1) seems to be linked with the albino locus situated on chromosome 7; the recombination percentage was about 29. In the first experiment with Bc I mice a significant difference was found between the tumour ages of the mice with virus-positive milk and of the mice with virus-negative milk: all mice (18) with viral antigens in the milk developed mammary tumours at an age ranging from 7 to 18 months, whereas in only 7 out of 16 mice with virus-negative milk were mammary tumours found before the age of 21 months. Viral antigens were detectable (by RIA) in the tumours of mice of both subgroups; however, the amounts (mU/mg tumour) were significantly lower in the tumours derived from mice with virus-negative milk. Although MTV-L of C3Hf mothers could be transmitted to BALB/c mice by foster-nursing, viral antigens could not be detected in milk samples collected prior to the third lactation period; thus an influence on the data of extrachromosomally transmitted MTV-L is unlikely.

Production by EBV infection of an EBNA-positive subline from an EBNA-negative human lymphoma cell line without detectable EBV DNA.

Abstract: A continuous lymphoma cell line, BJAB, derived from the tumour of an exceptional African case of Burkitt's lymphoma, has previously been described. Unlike 97% of African BL cases studied, neither the original tumour cells nor the cell line contained detectable amounts of EBV (Epstein-Barr virus) DNA, nor did they express the EBV-determined nuclear antigen EBNA. The cells of the established line had the characteristics of B-type lymphocytes and they carried receptors for EBV. EBNA was induced in the majority of BJAB cells after EBV infection. Usually the cells died within 10 days of infection, but it was possible to establish a permanent EBNA-positive variant (GC-BJAB) of BJAB. The patient from whose tumour the original BJAB line was established was seropositive for EBV antigens, indicating previous exposure to and continuing presence of the virus; yet the tumour had not become infected by EBV. This evidence shows that EBV is not readily "picked up" by the lymphoma.

Origin and partial characterization of Fc receptor-bearing cells found within experimental carcinomas and sarcomas.

Abstract: A variety of murine connective and epithelial tissue tumors, including the SAD/2 and FS9 fibrosarcomas, the TA3/Ha and CAD/2 mammary carcinomas and a primary methylcholanthrene-induced sarcoma, were found to contain a high proportion of cells with receptors for the Fc portion of immunoglobulin G ("Fc receptors"). Experiments were undertaken to assess whether these cells were neoplastic, or whether they represented the infiltration into the tumor of non-malignant host cells such as macrophages or lymphocytes. It was found that long-term established in vitro cell lines of the TA3/Ha SAD/2 and CAD/2 tumors were entirely negative for the Fc receptor, whereas injection of these cells led to the formation of tumors containing a high proportion of Fc receptor-bearing cells. Many of these cells were actively phagocytic as assessed by ingestion of iron filings or antibody-coated erythrocytes. Injection of Fc receptor-negative cultured tumor cells into F1 hybrids, in which host cells could be distinguished from the tumor cells by anti-H2 sera, revealed that many or all of the Fc receptor-bearing cells in the resultant tumor were of host origin. In contrast to its effect on normal spleen cells, anti-theta serum treatment also partially inhibited Fc rosettes, suggesting a T-lymphocyte origin for some of the Fc receptor-bearing cells. Since almost all cells with potential anti-tumor activity bear Fc receptors, it is suggested that an index of host cell infiltration of carcinomas and sarcomas can quickly and easily be ascertained by enumeration of Fc receptor-bearing cells.

Distinctive banded marker chromosomes of human tumor cell lines.

Abstract: Nine human tumor cell lines (five breast carcinomas and four sarcomas) have been studied and each revealed groups of distinctive banded marker chromosomes which can serve to identify them and aid in monitoring cell line specificity. This was possible neither by conventional karyology in terms of numbers and morphology of chromosomes nor by glucose-6-phosphate-dehydrogenase mobility which was type B for all cultures. The significance of the clonal nature of the cell lines is discussed.

Epoxides metabolically produced from some known carcinogens and from some clinically used drugs. I. Differences in mutagenicity.

Abstract: The epoxide metabolites of two clinically used drugs and an experimental psychotropic agent, carbamazepine 10,11-oxide, cyproheptadine 10,11-oxide and cyclobenzaprine 10,11-oxide, were fully devoid of any mutagenic activity under conditions where K-region-epoxide metabolites of some known carcinogens, such as benzo (a)pyrene, proved to be potent frameshift mutational agents for Salmonella typhimurium TA 1537 and TA 1538. All epoxides tested were non-mutagenic for TA 1535, designed to detect substitution mutations. The 10,11-epoxides of the three drugs, carbamazepine, cyproheptadine and cyclobenzaprine, were not cytotoxic to any of the bacterial tester strains used, precluding that mutagenicity might have been overshadowed by cytotoxicity. When the mutagen precursor, benzo (a)pyrene, was incubated together with TA 1537 and a mammalian microsomal preparation in the presence of a system generating the co-factor necessary for mono-oxygenase activity, activation to mutagenic species was observed which was dramatically increased in the presence of a potent epoxide hydratase inhibitor, 1,1,1-trichloropropene 2,3-oxide, suggesting epoxide (s) as the (or one of the) mutagenically active species metabolically produced in situ. None of these effects was observed with the three medical drugs. Moreover, the observation that the alkene oxide 4-phenylstyrene 7,8-oxide is mutagenic to the two strains TA 1537 and TA 1538 but the K-region arene oxide derived from 7,12-dimethylbenz (a) anthracene is inactive for the latter strain indicates that epoxidation of an aromatic double bond of a polycyclic hydrocarbon is neither a necessary nor a satisfying condition for frameshift mutagenesis to occur.

Occurrence of nervous-tissue tumors in cattle, horses, cats and dogs.

Abstract: From 11 North American veterinary university hospitals and clinics, 248 animals were a confirmed diagnosis of nervous-tissue tumor were identified; 7 tumors were found in cattle, 28 in horses, 14 in cats, 199 in dogs, and none in other species. Tumors were divided for analysis into three categories-glial, meningeal, and peripheral nerve. In cattle and horses, all tumors involved peripheral nerves, the risk of which, in horses, reached a plateau at 4-6 years of age and remained constant thereafter. In cats, the tumors were equally distributed among the three tumor categories whereas, in dogs, twice as many glial tumors as meningeal and peripheral nerve tumors were found. The risk for glial tumors in dogs reached a peak at 10-14 years of age, for meningeal at 7-9 years, and for peripheral nerve at 2-3 and 7-9 years. Three canine breeds-English bulldog, boxer, and Boston terrier-had an excessive rish of glial tumors. Except for an excess of skin tumors in dogs with peripheral nerve tumors, there was no unusual occurrence with second primary neoplasms for any species. There was no detectable predisposition by sex for any of the categories of nervous-tissue tumors among any of the four species. The role of genetic abnormalities associated with nervous-tissue tumors and other etiologic factors (e.g., chronic hypoxia) may be clarified by further studies involving canine breeds of "bulldog" ancestry.

Leukocyte adherence inhibition and specific immunoreactivity in malignant melanoma.

Abstract: The leukocyte adherence inhibition (LAI) test has been used to assess specific anti‐tumour immunoreactivity in 80 patients with malignant melanoma, 21 of whom had apparently been successfully treated by surgey, and 44 control subjects. Reaction with melanoma extracts in vitro enabled the activity of blood leukocytes to be detected by inhibition of their adherence to glass, while serum was tested for factors which modified this inhibition. Of the patients with tumours (ranging from primary melanoma in situ to advanced disseminated disease), 22/24 had active leukocytes and 50/58 had serum blocking factor; two of the sera, from patients with regressing tumours, were unblocking. After surgery with no clinical recurrence, leukocytes continued to be active except when tested several years after operation. Blocking factor rapidly disappeared in 16/20 patients tested, and in several patients examined serially the serum became unblocking. In three cases, persistence of serum blocking was followed by clinical diagnosis of metastases. Leukocyte activity was never detected in control subjects (0/10), many of whom had other kinds of tumours or skin lesions. Blocking activity in serum was found in only 3/38 controls with no history of melanoma (1 had a fibrosing cellular blue naevus and 2 had liver disease). Thus the LAI test correlated well with clinical and pathological findings, and shows great promise for the reliable, rapid and specific immunodiagnosis of malignant melanoma.

Inhibition of in vitro lymphoproliferative responses to tumor-associated antigens by suppressor cells from rats bearing progressively growing Gross leukemia virus-induced tumors.

Abstract: W/Fu rats were injected subcutaneously with low numbers of cells from the Gross leukemia virus-induced lymphoma, (C58NT) D, which induced transient tumor growth and regression (regressors), or with high numbers of tumor cells resulting in progressive tumor growth (progressors). Spleen cells from regressors had a significant reactivity in the mixed leukocyte tumor cell interaction (MLTI), while spleen cells from progressors were unresponsive. Similarly, the responses to the non-specific mitogens, phytohemagglutinin and concanavalin A, were suppressed in spleen-cell cultures of progressors. Passage of spleen cells from progressors over rayon adherence columns or pretreatment with an iron/magnet technique resulted in almost complete restoration of MLTI and mitogen responses. Addition of spleen cells from progressors depressed the MLTI of spleen cells from regressors and the mitogen reactivity of normal spleen cells. Serum from progressors also suppressed MLTI and mitogen reactivity. These data indicate that, in spleens of rats bearing progressively growing tumors, suppressor cells can be demonstrated which inhibit specific reactivity to tumor-associated antigens and non-specific reactivity to mitogens. The presence of suppressor cells or of inhibitory factors in the serum may contribute to the immunosuppression frequently observed in tumor-bearing hosts.

Mutation induction in chinese hamster V79 cells by two vinyl chloride metabolites, chloroethylene oxide and 2-chloroacetaldehyde

Abstract: Chloroethylene oxide and 2-chloroacetaldehyde, two possibly carcinogenic metabolities of vinyl chloride in mammals, caused a dose-dependent induction of 8-azaguanine- and ouabain-resistant mutants in Chinese hamster V79 cells in vitro. Up to one-hundred-fold higher concentrations of 2-chloroethanol or monochloroacetic acid, a urinary vinyl chloride metabolite in rats and man, were inactive.