Showing papers on "Cytotoxic T cell published in 1971"

Suggestive evidence that the "blocking antibodies" of tumor-bearing individuals may be antigen--antibody complexes

Abstract: Sera from mice carrying progressively growing sarcomas induced by Moloney virus or methylcholanthrene can block the cytotoxic effect of lymphocytes immune to the tumor-specific antigens of the respective neoplasms. The blocking effect can be specifically removed by absorbing sera with the respective types of tumor cells, and it can be recovered from these cells by elution at low pH. If the low pH is maintained, it is possible to separate out a low and a high molecular weight fraction from the eluates. If the fractions are added to the target cells for 45 minutes and then removed, neither of these fractions can block lymphocyte-mediated cytotoxicity, while a 1:1 mixture of them has a specific blocking effect. If they are admixed with the lymphocytes, incubated for 1 hr, and then allowed to incubate with the target cells and lymphocytes during the entire 2 days of the test, the low molecular weight fraction, as well as the mixture, but not the high molecular weight fraction, has a blocking activity. It is suggested that the blocking factor in sera from tumor-bearing animals, as regularly tested, is an antigen-antibody complex, capable of binding to the target cells and/or reacting with lymphocytes immune to their antigens, thus blocking the lymphocytes' reactivity; the latter reaction is postulated to be of a temporary nature.

Endotoxin and double stranded RNA render macrophages cytotoxic.

Abstract: The cytotoxicities of double stranded RNA and endotoxin have striking similarities. Both seem to render mouse macrophages cytotoxic to other mouse cells.

Immunoglobulin and other surface antigens of cells of the immune system.

Abstract: Immunoglobulins (Ig) on cells of the immune system: The cytotoxicity test, with class-specific and type-specific anti-Ig sera, identifies κ and µ determinants on mouse lymphocytes. The proportion of κ+ cells is characteristic for each source of cells: 30% of bone marrow cells, 40% of cells from peripheral lymph nodes, 45% of lymphocytes from peripheral blood or peritoneal cavity, and 50% of spleen cells. No Ig was demonstrable on thymocytes or on leukemia cells (most of which arise from thymus-derived [T] cells). Cytotoxicity tests were performed on various myelomas secreting different Ig; the only positive reactions were given by κγ1 myelomas (all four κγ1 myelomas tested were sensitive to both anti-κ and anti-γ1). Hemolytic plaque-forming cells (PFC) of IgG type had no demonstrable surface Ig, but a proportion of IgM PFC were κ+µ+. Virtually all rosette-forming cells (RFC) have surface Ig, more than 90% of them being inhibited by anti-κ, 50% by anti-µ, and 10–30% by antisera to other heavy chains. Anti-λ sera gave no positive reactions with any cell type, which is in keeping with the low level of this light chain in mouse serum. Ig and other differentiation antigens as markers for T and B cells: Thymocytes are hallmarked by the alloantigens TL, θ, and the Ly series, and it is generally held that extrathymic lymphoid cells that bear them are derived from thymocytes. There is one alloantigen marker for the thymus-independent (B) cell, and that is PC, which appears late in differentiation. (The mouse-specific lymphocyte (MSLA) and mouse-specific bone marrow-derived lymphocyte (MBLA) antigens recognized by heteroantisera, not used in the present study, are other candidates for T and B cell markers.) Making use of antisera to these surface antigens to inhibit the function of cells that carry them, we find the following: Approximately 30% of RFC, 60% of IgM PFC, and 90% of IgG are PC+ and so are identified as B cells. No T markers were demonstrable on these cell populations. Thus if T cells do become RFC or PFC they presumably lose their T surface markers in the process (cf. the quantitative reduction of T markers accompanying the thymocyte → lymphocyte transition). Cells that have the potential to initiate graft-versus-host (GVH) reactions have the T cell surface phenotype θ+Ig-. Adoptive transfer of thymus-dependent antibody-forming capacity (response to sheep erythrocytes) required θ+ cells but transfer of a thymus-independent immune response to Brucella antigen did not. Cells with surface Ig were involved in both types of adoptive transfers. Thus the presently available T markers do not provide evidence for T cells carrying surface Ig. Suppression of the Ig phenotype by antibody: antigenic modulation? A phenotypic change from Ig+ to Ig- occurs when Ig+ lymphocytes or myeloma cells are incubated with anti-Ig sera in vitro in the absence of complement (C). As with antigenic modulation in the TL system, which it resembles, this phenomenon is temperature dependent and in the case of lymph node cells (LNC) can be inhibited by high doses of actinomycin D.

Natural Thymocytotoxic Autoantibody and Reactive Antigen in New Zealand Black and Other Mice

Abstract: Naturally occurring thymocytotoxic autoantibody (NTA) was detected by cytotoxic test in the sera of very young New Zealand Black mice (within 1 month after birth); the incidence was 100% at 3 months of age. Some mice from other strains also had NTA, but at an older age and with lower incidence and antibody titer. NTA had optimal activity at 4°C but was also strongly reactive at 37°C. It was cytotoxic for thymocytes of all strains of mice tested. Whereas only thymocytes were highly sensitive to NTA, the reactive antigen was demonstrated by absorption test in the thymus, lymph node, spleen, and brain of adult mice. It could be demonstrated only in the thymus of newborn mice. The distribution of NTA-reactive antigen suggests the presence of an antigen distinct from any so far described on the cell surface of mouse thymocytes. Gel filtration of NZB mouse serum suggests that NTA is an IgM. Mouse thymocytes sensitized with NTA in vitro became highly susceptible to phagocytosis by syngeneic macrophages.

Cells mediating specific in vitro cytotoxicity. I. Detection of receptor-bearing lymphocytes.

Abstract: Spleen cells from mice immunized with allogeneic tumor cells are incubated on different fibroblast monolayers. The nonadsorbed cells are tested for cytotoxicity against 51Cr-labeled target cells. The cytotoxicity of nonadsorbed cells is much lower after incubation on fibroblasts syngeneic to the immunizing tumor cells than after incubation on fibroblasts syngeneic to the immune cells. This specific decrease of cytotoxic activity depends on the duration and temperature of incubation on monolayers. After incubation the monolayers are trypsinized and pure populations of adsorbed lymphocytes isolated by density gradient fractionation. The cytotoxicity of such trypsin-eluted, gradient-purified lymphocytes is much higher when these lymphocytes are isolated from fibroblasts syngeneic to the immunizing tumor cells than when they are isolated from fibroblasts syngeneic to the immune cells. These experiments demonstrate specific adsorption of immune cells onto fibroblasts carrying the immunizing antigens, and thus prove the existence of specific receptors at the surface of these immune cells. Spleen cells from mice immunized with two types of allogeneic tumor cells bearing different H-2 antigen alleles are incubated on different fibroblast monolayers. The results of such experiments show a differential specific adsorption pattern, suggesting independent adsorption of two populations of immune cells bearing receptors directed against either one or the other immunizing H-2 antigen. The existence of at least a majority of cells, each of which is homogeneous as to the specificity of its receptors, makes it likely that specific receptors are synthetized by the cells that bear them. The role of specific receptor-bearing cells in the killing process is discussed.

Cell-to-cell interaction in the immune response. Vii. Requirement for differentiation of thymus-derived cells.

Abstract: Experiments were designed to test the possibility that thymus-derived (T) cells cooperate with nonthymus derived (B) cells in antibody responses by acting as passive carriers of antigen. Thoracic duct lymphocytes (TDL) from fowl γG-tolerant mice were incubated in vitro with fowl anti-mouse lymphocyte globulin (FALG), which was shown not to be immunosuppressive in mice. On transfer into adult thymectomized, irradiated, and marrow protected (TxBM) hosts together with a control antigen, horse RBC, a response to horse RBC but not to fowl γG was obtained. By contrast, TxBM recipients of nontolerant, FALG-coated TDL responded to both antigens and the antibody-forming cells were shown to be derived from the host, not from the injected TDL. These findings suggested that, under the conditions of the experiment, triggering of unprimed B cells in the spleens of TxBM hosts was not achieved with antigen-coated tolerant lymphocytes. Another model utilized the ability of B cells to bind antibody-antigen complexes. Spleen cells from TxBM mice, incubated in vitro with anti-fowl γG-fowl γG·NIP, were injected with or without normal TDL (a source of T cells) into irradiated hosts. Only mice given both cell types could produce an anti-NIP antibody response. In a further experiment, spleen cells from HGG·NIP-primed mice were injected together with NIP-coated B cells (prepared as above) into irradiated hosts. A substantial anti-NIP antibody response occurred. If, however, the T cells in the spleens of HGG·NIP-primed mice were eliminated by treatment with anti-θ serum and complement, the NIP response was abolished. It was concluded that antigen-coated B cells could not substitute for T cells either in the primary or secondary response. Treatment of T cells from unprimed or primed mice with mitomycin C impaired their capacity to collaborate with B cells on transfer into irradiated hosts. Taken together these findings suggest that before collaboration can take place T cells must be activated by antigen to differentiate and in so doing may produce some factor essential for triggering of B cells.

Mouse specific bone marrow-derived lymphocyte antigen as a marker for thymus-independent lymphocytes.

Abstract: THE usefulness of the theta (θ) alloantigen as a marker for thymus-derived lymphocytes in mice1–6 has emphasized the need for a distinguishing marker for thymus-independent (bone marrow-derived) lymphocytes, about which relatively little is known. We have raised an antiserum in a rabbit against lymph node cells from mice which had been thymectomized, irradiated and reconstituted with foetal liver cells, which after appropriate absorption was cytotoxic only to those lymphoid cells which were thymus-independent. Because the cell surface antigen(s) with which the antiserum is principally reacting seems to be species-specific, we have followed the example of Shigeno et al.7 and have called it MBLA (mouse-specific bone marrow-derived lymphocyte antigen).

Immunization with Irradiated Tumour Cells and Specific Lymphocyte Cytotoxicity in Malignant Melanoma

Abstract: A microculture technique has been adapted to assay the cytotoxic properties of the lymphocytes from patients with malignant melanoma when cultured with their autologous tumour cells. In a series of patients with established melanoma specific autologous cytotoxicity was extremely uncommon, being detectable in only 3 out of the 22 cases studied. This cytotoxicity did not correlate with clinical staging of the disease but may well have been related to tumour volume. By autoimmunization of patients with an irradiated suspension of their own tumour cells the appearance of cytotoxic lymphocytes could be provoked in 5 out of the 12 patients studied. This cytotoxicity was detectable at the end of the first week after the autograft and disappeared by the third week. Cytotoxic lymphocytes did not correlate in any obvious way with the appearance of specific antitumour antibodies detected by immunofluorescence. So far there has been no evidence of a serum factor capable of blocking the lymphocyte cytotoxicity in these patients.The presence and possible significance of cytotoxic lymphocytes in patients with malignant disease is discussed.

Cytotoxic lymphocytes from rats depleted of thymus processed cells.

Abstract: THE mechanisms by which lymphocytes damaged antigenically foreign cells are thought to be of fundamental importance in the rejection of allografts and neoplastic cells. Studies by Cerottini, Nordin and Brunner1, 2 in mice sensitized to allogeneic target cells have shown that their cytotoxic activity is attributable to thymus-derived lymphocytes, which act directly on the target cell. These lymphocytes do not seem to require the cooperation of other lymphoid populations. But we have shown in rats that immunologically specific damage by lymphocytes to xenogeneic target cells requires the participation of two populations of lymphoid cells3, 4. One population produced IgG specific for target cell antigens, but was not itself cytotoxic, and the other population showed cytotoxic activity against target cells, the antigens of which were complexed with specific antibody. Therefore, in this system the specificity of the cytotoxic effector cell is directed at a determinant on antibody, rather than at target cell antigen. In a previous report5 we presented indirect evidence which suggested that the effector lymphocyte in this antibody-dependent cytotoxic system was not thymus processed and we are now providing direct evidence for this.

Studies on nondefective adenovirus-simian virus 40 hybrid viruses. I. A newly characterized simian virus 40 antigen induced by the Ad2+ND 1 virus.

Abstract: The nondefective adenovirus 2 (Ad2)-simian virus 40 (SV40) hybrid virus, Ad2+ND1, does not induce heat-labile SV40 T antigen but does induce a previously uncharacterized heat-stable SV40 antigen—the SV40 “U” antigen. This antigen is detectable by both immunofluorescence and complement fixation by using sera from hamsters with SV40 tumors. Sera from hamsters bearing SV40 tumors can be divided into two groups, those that react with both SV40 T and U antigens (T+U+ sera) and those that react with SV40 T antigen only (T+U− sera). SV40 U-specific sera from monkeys immunized with Ad2+ND1-infected cells do not react with SV40 T antigen by immunofluorescence but do react with an antigen in the nucleus of SV40-transformed cells and with an early, cytosine arabinoside-resistant antigen present in the nucleus of SV40-infected cells. A heat-stable SV40 antigen detectable by complement fixation with T+U+ hamster sera is present in extracts of SV40-induced hamster tumors and in cell packs of SV40-infected or -transformed cells. SV40 U-antigen synthesis by Ad2+ND1 virus is partially sensitive to inhibitors of deoxyribonucleic acid synthesis, whereas U-antigen synthesis by SV40 virus is an early cytosine arabinoside-resistant event. As an early SV40 antigen differing from SV40 T antigen, U antigen may play a role in malignant transformation mediated by SV40.

In vitro assay of target cell lysis by sensitized lymphocytes

Abstract: Publisher Summary Cytotoxic assay detects the presence of effector cells involved in cell-mediated immunity (CMI). By using Cr-labeled target cells, the cytotoxic activity of sensitized lymphocytes is detectable within less than one hour. So far the in vitro cytotoxic assay has been used to measure transplantation on CMI in mice. Preliminary experiments indicate that the same assay system could be used to measure CMI to soluble antigens. In this assay, lymph node cells, peritone almacrophages and embryonic fibroblasts have also been used as target cells. Sensitized-lymphoid cells are also obtained after transfer of cells from the spleen, lymph node, or thymus into lethally-irradiated allogeneic recipients.

The asynchronous development of immunological memory in helper (T) and precursor (B) cell lines.

Abstract: A simple method is described for distinguishing helper (T) and precursor (B) immunological memory: it depends on the sequential use of 2 cross-reacting antigens for priming and challenge. Using cow and sheep erythrocytes, we have followed the asynchronous development of helper and precursor memory. Helper (T) memory is optimal 4 – 6 days after a wide range of antigen doses (2 × 104 –2 × 109 red blood cells). It reaches rather higher levels after very small injections, but persists longer after high doses. Precursor (B) memory requires a large amount of antigen for optimal development (2 × 107 – 2 × 109 red blood cells). It increases for at least 2 months after priming. B-memory cells defined by the cross-reactive criterion are insensitive to anti-theta serum but require the presence of T cells for their effective stimulation by antigen. Precursor memory does not appear to be carried by the antibody-forming cells themselves. It is more sensitive to irradiation damage than T memory. Memory of either kind leads to increased production of both IgM and IgG antibody-forming cells. Helper memory cells seem to be able to interact with virgin B cells in the normal spleen.

In Vitro Detection of Cytotoxic Cellular Immunity Against Tumor-Specific Antigens by a Radioisotopic Technique

Abstract: [3H]Thymidine-labeled tumor cells are used to evaluate the cytotoxic cellular immune response against tumor-specific antigens; the loss of label due to destruction and detachment of target cells from the surface of the culture vessel is measured. Spleen cells from mice immunized against Moloney virus-induced rhabdomyosarcoma specifically destroyed the sarcoma cells, while cells from normal syngeneic mice did not. Peripheral blood lymphocytes from patients with malignant tumors were specifically cytotoxic to autologous tumor cells and to allogeneic tumor cells histopathologically identical to the autologous tumor, but not to autologous nonmalignant fibroblasts, or to allogeneic tumor cells from a histologically dissimilar tumor. Serum from the same patients specifically protected autologous tumor cells from lymphocyte cytotoxicity. This serum-mediated protection of tumor cells against autologous cellular immunocytotoxicity also extended to histologically identical allogeneic tumor cells. Cross-reactivity of anti-tumor cellular immunocytotoxicity in vitro, and its “blocking” by autologous serum, strongly suggest the presence of common tumor antigens. The antagonism demonstrated in vitro between serum and cellular immunity may explain the continued growth of malignant tumors in the face of demonstrable cellular immunity.

Cellular and humoral response to transplantation antigens. I. Development of alloantibody-forming cells and cytotoxic lymphocytes in the graft-versus-host reaction.

Abstract: After transfer into heavily-irradiated allogeneic mice, spleen cells were found to produce two types of effector cells directed against the recipient alloantigens, namely alloantibody plaque-forming cells (PFC) and cytotoxic lymphocytes (CL). Both types of effector cells were detectable in vitro by virtue of their lytic effect on target cells carrying the recipient alloantigens. Alloantibody PFC activity was dependent on the presence of an exogenous source of complement and could be inhibited by the addition of heterologous antisera to mouse µ-chain or Fab fragment in the assay system. CL activity was independent of added complement, was not affected by anti-immunoglobulin antisera, but was inhibited by the addition of antibody against target cell alloantigens. Treatment of the transferred spleen cells with anti-θ-serum and complement before in vitro assays for PFC and CL completely abolished the CL activity but had no effect on alloantibody-plaque formation. These results indicate that the two types of effector cells can be differentiated in vitro by virtue of their susceptibility to anti-θ-serum and the mechanisms by which they cause cell lysis.

"Unblocking" serum activity in vitro in the polyoma system may correlate with antitumour effects of antiserum in vivo.

Abstract: In a variety of tumour systems, individuals carrying progressively growing neoplasms have lymphoid cells with a specific cytotoxic effect on cultured tumour cells from the same individual1–4. Since the sera of tumour-bearing individuals have been shown to prevent tumour cell destruction by immune lymphocytes in vitro2,5–8 and since this serum blocking activity appears early in primary and transplant tumour development5,7, it has been suggested that the appearance of this serum blocking activity might be responsible for the progressive growth of tumours in individuals having cytotoxic lymphocytes. Counteraction of this blocking activity would thus be of primary importance in facilitating the function of an already existing or bolstered cell-mediated immunity. The serum blocking activity might be inhibited in various ways, by preventing the formation of blocking antibody or by interfering with its action (“unblocking”), as demonstrated in Moloney sarcoma regressor sera9. This type of serum also has a therapeutic effect on Moloney sarcomas in vivo10,11, which has been tentatively attributed to its unblocking activity8,9 or, possibly, to a complement-dependent cytotoxicity10. Tumour growth in the Moloney sarcoma system, however, might be due in part to continuous recruitment of neoplastic cells by virus-induced transformation and so the therapeutic effect could be due to a virus-neutralizing serum activity9,10.

Interaction of immune lymphocytes with the mixtures of target cells possessing selected specificities of the H-2 immunizing allele

Abstract: Optimum conditions have been found for a specific quantitative absorption of mouse lymphocytes on to allogeneic target cells. Using this technique, it has been established that C3H anti-A lymphocytes immune to the specificities of a single H-2 sub-locus (D) were absorbed neither on cells bearing only some of the components of the immunizing complex (DBA/1 and I/St targets) nor on their mixture. Conversely, C57BL anti-A lymphocytes immune to the specificities of two H-2 sub-loci (D and K) reacted separately with each of the components on corresponding third-party targets (B10.D2(H-2d) and C3H (H-2k) as shown both by the direct cytotoxic effect and by the quantitative absorption technique. The results of absorption of these lymphocytes on mixtures of B10.D2 and C3H target cells used in various proportions indicate that C57BL anti-A lymphocytes represent a mixture of two `polyvalent' populations in ratio of 1:3. This, together with the previous data indicates that `committed' lymphocytes may be `polyvalent' and that the initial recognition step of H-2 antigens may result from a direct contact between membranes of grafted cells and `unprimed' host lymphocytes. Structural matching of the membrane antigenic complex and of normal and immune lymphocytes is suggested as a decisive factor of immunological recognition initiation in a transplantation context.

Cell cooperation in antibody induction. The susceptibility of helper cells to specific lethal radioactive antigen.

Abstract: Irradiated mice were reconstituted with syngeneic spleen cells from mice immunized with 2,4-Dinitrophenyl(DNP)-ovalbumin or Maia squinado hemocyanin (MSH) and challenged with DNP-MSH In this hapten-carrier system MSH primed cells showed the expected helper activity for an anti-DNP response As previously shown for another system by Mitchison and Raff, the helper activity of MSH-primed cells could be attributed to thymus-derived (T) lymphocytes since it was suppressed by anti-Θ serum and complement Susceptibility of helper activity to lethal radioactive antigen was tested MSH-primed cells were incubated with [125I] MSH of high specific activity, a treatment known to suppress antibody secreting precursor cells Cell transfer experiments were carried out using two doses of cells With a low dose transfer (5 × 106 cells), [125I]MSH treatment suppressed the helper activity of MSH cells specifically indicating that thymus-derived lymphocytes must have antigen specific receptors and are susceptible to killing by radioactive antigen However, after transfer of a large number (25 × 106) of cells treated with [125I] MSH, helper activity was still present although the anti-MSH antibody forming capacity was completely suppressed This finding and the effect of anti-Θ treatment demonstrate the dissociation of T and B lymphocyte function The observation that a large dose of MSH-primed cells retained its helper function after radioactive antigen treatment could be attributed to an excess of MSH specific helper cell activity in spleen cells primed with MSH Limiting cell dilution experiments have shown that as few as 106 MSH-primed cells are sufficient to exert full helper activity in this system Thus more than 96% of the helper cells would need to be killed by lethal radioactive antigen to suppress the helper effect of 25 × 106 cells The analysis of the anti-MSH response showed that memory in the T cell population was not sufficient to obtain a secondary response and that memory in the B lymphocyte population was also required

Detection of an Antigen Associated with Acute Leukemia

Abstract: Antiserums to a purified cell membrane component from a Burkitt's lymphoma tissue culture cell line were produced in rabbits. These antiserums were cytotoxic to peripheral white blood cells from 8 of 15 patients with acute leukemia and 5 of 41 relatives, but not to peripheral white blood cells from leukemia patients in clinical remission or from normal individuals. These antiserums appear to be detecting an acute leukemia associated antigen or antigens.

Qualitative and Quantitative Studies of Cytotoxic Immune Cells

Abstract: A quantitative assay of in vitro cell-mediated cytotoxicity has been used to detect the appearance of cytotoxic cells in the spleens of immunized BALB/c mice. Biometric techniques which utilize dose response curves suggested quantitative and qualitative changes in immune activities of different lymphoid populations. The immune responses to intraperitoneal injections of allogeneic tumor cells were studied as functions of both time and immunizing cell dose. Spleen cell-mediated cytotoxicity was detectable 3 days after immunization. The response was maximal after about 10 days and then fell gradually. The highest response to a single intraperitoneal exposure occurred after injection of 10 7 EL-4 cells. Higher doses of cells resulted in lower responses. The response to a second immunizing dose of EL-4 cells was quicker and reached a peak at about 7 days. In addition to changes in total immune activity, a qualitative change occurred in cell-mediated immunity during the course of primary and secondary responses. With an increase in total immune activity, cytotoxic activity of the average immune cell appeared to increase. The time course and immunizing dose dependence of cytotoxic antibody levels and cell-mediated responses were similar after primary immunization. Hyperimmunization resulted in increasing cytotoxic antibody titers but decreasing cell-mediated activity. Cellular immunity in the hyperimmune animals appeared to have been stimulated but effectively suppressed. This suppression was reversible by transfer of the hyperimmune spleen cells with antigen to sublethally irradiated hosts.

Immunocompetent cells of the chicken. I. Specific surface antigenic markers on bursa and thymus cells.

Abstract: Specific antisera to chicken thymus and to bursa of Fabricius were obtained in rabbits. After appropriate absorption and dilution all four anti-thymus sera, in the presence of guinea pig C', killed >90% of thymus and 90% of bursa cells and <==10% of thymus cells. These antisera were cytotoxc for a large percentage of antibody-forming cells and killed approximately 30% of spleen cells The other two anti-bursa sera were somewhat less potent but showed similar specificity. The surface antigen detected by these antisera was named chicken bursa-derived lymphocyte antigen (CBuLA). Rabbit antisera to chicken immunoglobulin were cytotoxic for bursa but not for thymus cells and killed a similar percentage of spleen cells as did anti-bursa sera. They were also cytotoxic for antibody-forming cells.

Cytotoxic Lymphocytes as Effector Cells of Cell-Mediated Immunity*

Abstract: Publisher Summary This chapter discusses about cytotoxic lymphocytes as effector cells of cell-mediated immunity. Allograft and tumor immunity are considered to be manifestations of Cell-Mediated Immunity (CMI). The rejection of tumors and grafts could readily be transferred from sensitized donors to normal recipients with lymphocytes but not with serum. Because of the complexity of the in vivo immune reactions, much effort has therefore been devoted to the study of the in vitro effect of sensitized lymphocytes on cells bearing membrane-associated transplantation antigens. Some studies have suggested that graft rejection and/or in vitro cytotoxicity of immune lymphocytes might involve not only a direct specific effect of sensitized lymphocytes on antigenic target cells, but also mechanisms mediated by nonspecific substances, macrophages, or antibody. In the chapter, experiments are described which were designed to further study the specificity of target cell destruction by cytotoxic lymphocytes in vitro and to evaluate the potential role of nonspecific mechanisms, of macrophages, and of normal lymphocytes. It is explained that in vitro cytotoxicity of immune lymphocytes is mediated by thymus-derived effector cells, target cell lysis is highly specific, and that antibody, nonspecific substances, macrophages, and/or normal lymphocytes are apparently not involved.

Inhibition of Migration of Human Autogenous and Allogeneic Leukocytes by Extracts of Patients' Cancers

Abstract: Studies have shown the importance of the delayed hypersensitivity reaction in the body's defense against cancer. Production of migration-inhibitory factors is characteristic of the delayed hypersensitivity reaction. Delayed hypersensitivity to chemically induced tumors has been demonstrated in animals by inhibition of macrophage migration. In our study, preparations from 19 of 21 human tumors inhibited leukocyte migration. Some preparations were cytotoxic to both autogenous and allogeneic migrating leukocytes. Growth of heterologous hepatoma cells in tissue culture was not inhibited by some preparations that inhibited leukocyte migration. It appears that both cytotoxic and migration-inhibiting substances can be liberated by tumor-leukocyte interaction. Such factors may prevent interaction between cancer cells and human tumors and thereby inhibit the cellular immune response in cancer patients.

Identification of Further Antigens on Red Cells and Lymphocytes

Abstract: . Antigenic sites of Bgb and Bgc specificity are present on lymphocytes as well as on red cells. The Bgb group has been correlated with the W17 (Te57) white cell group, and the Bgc with the W28 (Da15, Ba*) antigen. Both haemagglutinating and cytotoxic antibodies can be absorbed by either red or white cells, though cross-reactivity was shown by many white cells. A haemagglutinin reacting with HL-A10 positive donors was found in some multispecific antisera. All these groups show weaker reactions with red cells than with lymphocytes.

Cytotoxic effects of some mineral dusts on syrian hamster peritoneal macrophages

Abstract: Hamster peritoneal macrophages were grown in cell culture and their response to various conditions was examined. The cultures responded favorably to high concentrations of serum and to medium which had been preconditioned by contact with tumor cells. After 2–3 days of adaptation, they entered into a period of stability which lasted from the 4th to the 9th day. Macrophage cultures in this stable phase were treated with various samples of mineral dusts and their response determined by counting the number of viable macrophages/cm2 at intervals over a period of 72 hr. Crystalline silica Snowit was found to be nontoxic. Amorphous silica Fransil caused a characteristic cytotoxic effect and a rapid decline in cell population at doses less than 150 µg/5 x 105 cells. Of the three different kinds of asbestos used, chrysotile was toxic and amosite and crocidolite nontoxic at equivalent concentrations. A comparison of two preparations of chrysotile which differed in surface area showed that weight rather than surface area determines toxicity. Pretreatment of chrysotile with tryptose phosphate broth under drastic conditions accelerated but did not increase the final intensity of the cytotoxic effect.

Studies of human sera with cytotoxic activity

Abstract: A B S T R A C T 42 human sera showing in vitro cytotoxic activity of restricted or broad HL-A specificities with test human lymphocytes were studied for the molecular and immunoglobulin class of cytotoxic antibody using sucrose gradient separations, DEAE-cellulose chromatography, and Sephadex G-200 gel filtration. Sera originated from patients with previous multiple pregnancies (19), multiply transfused patients (8), subacute bacterial endocarditis (4), systemic lupus (2), and human umbilical cord sera (9). In 32 of 42 instances, predominant cytotoxic activity was found in high molecular weight gradient fractions; however, DEAE chromatographic separations revealed cytotoxic activity in initial buffer fractions containing primarily -vG globulin. Gradient separations of cytotoxic activity within initial 'vG DEAE fractions showed localization of cytotoxicity only in high molecular weight materials. Confirmation of high molecular weight YG cytotoxic activity was obtained by resistance to mercaptoethanol treatment, abolition of activity after absorption only with specific anti-yG antisera, and by the finding that high molecular weight cytotoxic activity in gradients or gel filtration run at neutral pH 7.4 became 7S when separations were rerun at an acidic pH of 4.0. Such 7S activity again became rapidly sedimenting when the same fractions were again rerun in gradients at neutral pH. 19S iM cytotoxic activity was documented in a panel of 15 human sera containing anti-"I" cold agglutinins. In this instance the cytotoxic activity appeared to be related to the cold agglutinin antibody since it was mercaptoethanol sensitive and could be demonstrated in monoclonal antibody eluates containing primarily -yM.

Host immune response to a common cell-surface antigen in human sarcomas.

Abstract: Cytotoxic antibody was demonstrated in the serums of four patients with sarcoma against their own autologous sarcoma cells in tissue culture. The presence of a common cell-surface antigen in human sarcomas was suggested by the finding that 70 per cent (58 of 83) of serums from patients with different histologic types of sarcomas were cytotoxic to an osteosarcoma cell line, whereas in serums from patients with other types of neoplasms cytotoxic antibody was no more frequent than in normal blood-donor serums. Further cross-reactivity studies revealed the common sarcoma antigen on tissue-culture cells from four different human sarcomas. Immunization of patients with sarcoma with their own irradiated sarcoma cells induced an increased immune response to this common sarcoma antigen, with a rising titer of cytotoxic antibody.