Showing papers on "Antigen published in 1977"

Immunofluorescence detection of new antigen-antibody system (delta/anti-delta) associated to hepatitis B virus in liver and in serum of HBsAg carriers.

Abstract: A new antigen-antibody system associated with the hepatitis B virus and immunologically distinct from the HB surface, core, and e systems is reported. The new antigen, termed delta, was detected by direct immunofluorescence only in the liver cell nuclei of patients with HBsAg positive chronic liver disease. At present, the intrahepatic expression of HBcAg and delta antigen appears to be mutually exclusive. No ultrastructural aspect corresponding to the delta antigen could be identified under the electron microscope. delta antibody was found in the serum of chronic HBsAg carriers, with a higher prevalence in patients with liver damage. The nuclear fluorescence patterns of HBcAg and delta antigen were similar; it is only possible to discriminate between the two antigens by using the respective specific antisera.

Identification of a transformation-specific antigen induced by an avian sarcoma virus.

Abstract: GENETIC analyses of avian sarcoma viruses (ASV) have led to the identification of a gene, designated src, which encodes a product required for the initiation and maintenance of neoplastic transformation in infected fibroblasts1–5. Because the src gene product has not been identified biochemically, this study was initiated to detect a transformation-specific protein, using serum from rabbits bearing ASV-induced tumours. We describe here the identification of a 60,000-MW transformation-specific antigen detectable in ASV-transformed chicken cells and ASV-induced hamster tumour cells by immunoprecipitation of radiolabelled cell extracts with serum from tumour-bearing rabbits. Moreover, the expression of this antigen is temperature dependent in chicken cells transformed by an ASV temperature-sensitive mutant in the src gene. The use of this antiserum may lead to the unequivocal identification and characterisation of the ASV src gene product and this, in turn, may lead to the elucidation of the mechanism of ASV-induced oncogenesis.

Effects of the new anti-lymphocytic peptide cyclosporin A in animals.

Abstract: The fungus metabolite cyclosporin A is a small cyclic peptide acting as a novel antilymphocytic agent It is effective following either parenteral or oral administration in mice, rats and guinea-pigs The suppressive effect after short and prolonged treatment on plaque-forming cells, the inhibition of the secondary humoral response and the reversibility of its effect on haemagglutinin formation is demonstrated Cyclosporin A inhibits delayed hypersensitivity skin reaction to oxazolone (primary and secondary responses) in mice and to tuberculin in guinea-pigs Its failure to suppress antibody synthesis to lipopolysaccharide antigens in nude mice suggests a selective effect on T cells High doses of the compound affect the haemopoietic tissues very weakly as shown by the bone marrow and stem cell numbers in mice, which finding markedly contrasts with most other immunosuppressive and cytostatic drugs

Radioimmunoassay for tumor antigen of human cervical squamous cell carcinoma

Abstract: A heterologous antiserum for human cervical squamous cell carcinoma was prepared and specificity determined by Ouchterlony immunodiffusion and immunofluoresence studies. With this antiserum, a tumor antigen was purified from human cervical squamous cell carcinoma tissue. The specificities of the antigen and the antiserum were then re-examined by a radioimmunoassay method using 125I-labeled purified antigen. Although normal cervical tissue extract showed a moderate cross-reactivity in the radioimmunoassay, the circulating antigen activity could not be detected in normal women or in several patients with other carcinomas, whereas 27 of 35 patients with cervical squamous cell carcinoma showed detectable serum antigen activity. All patients with advanced stages of cervical squamous cell carcinoma showed detectable antigen levels. These results indicate that there is a quantitative abnormality, at least, of this tumor antigen in patients with cervical squamous cell carcinoma and that the radioimmunoassay for the antigen is a potentially useful tool in clinical care.

Ia antigen expression on human epidermal Langerhans cells.

Abstract: IT has been proposed that the mammalian epidermal Langerhans cell is an epidermal equivalent of the cells of the reticulo-endothelial system, which are involved in binding and presentation of allergens in lymph nodes and the spleen1,2. The demonstration that these resident cells are capable of binding various allergens and migrate to the lymph vessels and local draining nodes, indicates a major function in the afferent arm of the primary immune response3,4 and has improved understanding of contact allergic hypersensitivity reactions. Much still remains to be discovered concerning the characteristics of the cell type, its reactivity with various antigens, and its relationship to other cells of the immune system. We show here that epidermal Langerhans cells react positively by immunofluorescence with antisera raised in rabbits against human B lymphoblastoid cell line membrane glycoproteins, which indicates the presence of Ia-like antigens on these dendritic cells.

Epidermal Langerhans cells bear Fc and C3 receptors.

Abstract: THE mammalian epidermis contains a system of dendritic cells, eponymously referred to as Langerhans cells, whose functions are obscure. It is, however, accepted that Langerhans cells are of mesenchymal origin and since they are known also to occur in the dermis, lymph nodes, thymus, and other organs, the concept of Langerhans cells has widened to encompass a cellular system populating the connective tissues and certain stratified squamous epithelia of mammals1. Among the many hypotheses about their biological significance they have been considered to represent immunocompetent cells or cells which might capture antigenic materials2, but there is insufficient evidence for this. Lymphocytes have been observed to be closely associated with Langerhans cells in delayed type hypersensitivity reactions to dinitrochloro-benzene in guinea pigs3; and when guinea pigs passively sensitised with lymphocytes from ferritin-hypersensitive donors, were challenged with ferritin, ferritin-containing Langerhans cells were observed in the draining lymph nodes of the challenged animals4. Metals and certain amines have an affinity for Langerhans cells in vitro5, but since they can phagocytose ferritin and other substances without previous sensitisation1, doubt remains whether they are immunologically engaged in the uptake and transport of potentially antigenic material. If Langerhans cells are indeed involved in immunological reactions, they should bear some of the surface markers characteristics of cells with known immunological functions, and we have now shown that they carry receptors for Fc and C3.

Experimental Allergic Uveitis. Isolation, Characterization, and Localization of a Soluble Uveitopathogenic Antigen from Bovine Retina

Abstract: The soluble antigen involved in the pathogenesis of EAU was isolated from bovine retinal extract by precipitation with ammonium sulfate followed by molecular sieve and ion exchange chromatography The purified fraction formed a double precipitin band by immunodiffusion and immunoelectrophoresis, and a doublet by analytical disc electrophoresis By immunodiffusion one of these components formed a reaction of identity with guinea pig S antigen and the other a reaction of partial identity Because the two components had the same mw and similar electric mobility, they are presumed to be minor structural variants of the same molecule The purified antigen had a mw of approximately 102,000 by analytical ultracentrifugation, 50,500 by SDS electrophoresis, and 56,000 by gel filtration chromatography Sedimentation velocity studies with increasing concentrations of antigen indicated self-association An S 20 value of 36 was obtained for the monomer, corresponding to an approximate mw of 50,000 The antigen was identified as a protein with a very small amount of lipid Data are presented on the absorption spectrum, extinction coefficient, and amino acid composition The molecule was lacking in cysteine and tryptophan, but contained a relatively high proportion of nonpolar amino acids corresponding with a lipophilic protein It was localized by immunofluorescence to the area surrounding the entire photoreceptor cell in a pattern indicating association with the plasma membrane The antigen was not rhodopsin, which has been implicated as a probable antigen in the pathogenesis of EAU, but has some properties resembling a recently described photoreceptor cell retinol-binding protein tentatively implicated in the transport of vitamin A from the circulation to the retina Assay of the purified fraction for production of EAU in the guinea pig indicated it was highly pathogenic in the microgram range In agreement with immunofluorescent findings, the photoreceptors were specifically destroyed after cellular infiltration of the uveal tract

In a radiation chimaera, host H–2 antigens determine immune responsiveness of donor cytotoxic cells

Abstract: CELL membrane structures controlled by genes in the major histocompatibility complex (H–2 in mice) are involved in most immune interactions between T lymphocytes and other cells1. Cytotoxic T lymphocytes (CTL) immunised against viruses2, haptens3, minor histocompatibility antigens4 or tumour antigens5, are specific for self H–2 antigens as well as for the foreign antigen. But CTL are not restricted to recognising antigens in combination with only self H–2. H–2d homozygous CTL which have matured in an irradiated H–2d/H–2k host can respond to antigen plus H–2k in addition to antigen plus H–2d (refs 6–8). It is not known whether the H–2 environment in which T cells mature influences their range of specificity, that is, whether CTL from a normal mouse can respond quantitatively as well to antigen plus foreign H–2 as they do to antigen plus self H–2. These experiments were designed to test this influence. The results suggest that host H–2 antigens do exert an effect on the specificity of T-cell responses.

Epidermal Langerhans cells express Ia antigens.

Abstract: THE major histocompatibility complex (MHC) of mouse and man controls the expression of several cell surface antigens1. The classical transplantation antigens are present on most if not all adult, nucleated cells. However, molecules controlled by the immune response region of the MHC display a much more restricted tissue distribution. The immune response-associated antigens (the Ia antigens in the mouse and HLA-D antigens in man) seem to be integral parts of the plasma membrane of B and T lymphocytes, macrophages, spermatozoa, and epidermal cells2. The physiological role of the Ia antigens is far from understood but their participation in various immunobiological events is well documented (for a review, see ref. 3). In addition to their role as triggers in the mixed leukocyte reaction4, the Ia antigens are required for collaboration between T and B lymphocytes5 and between macrophages and T cells6. Since all known functions of the Ia antigens pertain to the immune system it seemed that they should be expressed on an epidermal cell population involved in immune reactions. We therefore set out to investigate which of the three cell types of epidermis, keratinocytes, melanocytes, and Langerhans cells, expresses the Ia antigens, and from the results of fluorescent antibody staining we conclude that it is the Langerhans cells.

Avidity of anti-DNA antibodies in serum and IgG glomerular eluates from patients with systemic lupus erythematosus. Association of high avidity antinative DNA antibody with glomerulonephritis.

Abstract: Significant differences in both specificity and avidity of anti-DNA antibodies were observed in the sera of groups of patients with active systemic lupus erythematosus glomerulonephritis, active systemic lupus erythematosus without nephritis, and in IgG eluates obtained by DNAase digestion of isolated glomeruli from glomerulonephritic kidneys. With methylated albumin-kieselguhr fractionated 3H-HeLa DNA as a source of native or single-strand DNA antigen in a modified Farr assay, an increased level of antibody to native DNA was associated with active systemic lupus erythematosus, particularly active nephritis. The avidity of antinative DNA estimated from plots of the reciprocals of bound and free antigen according to the Sips distribution formula was significanly lower in active glomerulonephritis sera than in sera from patients with active systemic lupus erythematosus without nephritis. However, antinative DNA of uniformly high avidity was found in the glomerular eluates. Avidity of single-strand DNA antibodies did not differ in the various patient groups. The data stronly supprot a major role for high avidity antinative-DNA in DNA/antiDNA immune complex-induced glomerular injury in systemic lupus erythematosus.

EB virus-induced B lymphocyte cell lines producing specific antibody.

Abstract: EPSTEIN–BARR virus (EBV) is a lymphotropic herpesvirus that converts normal human B lymphocytes into established lines. This ‘immortalisation’ preserves the characteristics of the original B cell, including EBV receptors, complement receptors, surface immunoglobulin and secretory immunoglobulin. Surface immunoglobulin is most frequently IgM. EBV-immortalised lines carry multiple copies of the viral genome, detected by nucleic acid hybridisation, and regularly express an EBV-specific nuclear antigen, EBNA. It has been suggested1 that all B-cells carry EBV receptors. If so, and if all B cells can be transformed into lines by EBV, it should be feasible to establish permanent lines from B lymphocytes capable of producing specific antibodies against appropriate antigens. Clearly, in view of the polyclonal transformation obtained after infection of B lymphocytes with a transforming virus strain, for example, B95-8, it will be necessary to pre-select lymphocytes with the appropriate antigen combining site. Resetting with antigen-coupled erythrocytes is one of the conceivable methods for such pre-selection. While this will select lymphocytes with the appropriate surface immunoglobulin receptors, it was recently shown that EBV-transformation activates normal lymphocytes and induces the release of secretory immunoglobulin2. If the procedure is successful, the established lines might therefore be expected to carry the appropriate surface receptor and also to secrete the corresponding antibody. This was actually found in this study, opening the way to the establishment of cell lines producing specific antibodies of choice.

Synthesis of Factor VIII Antigen by Cultured Guinea Pig Megakaryocytes

Abstract: Immunoprecipitates containing guinea pig Factor VIII antigen were prepared from guinea pig plasma with a cross-reacting rabbit anti-human Factor VIII. Monospecific antisera to guinea pig Factor VIII antigen were produced in rabbits by using these washed immunoprecipitates as immunogens. The resulting antisera to guinea pig Factor VIII antigen detected Factor VIII antigen in guinea pig plasma and inhibited the von Willebrand factor activity in guinea pig plasma. This antibody also detected Factor VIII antigen in a solubilized protein mixture prepared from isolated cultured guinea pig megakaryocytes. Cultured guinea pig megakaryocytes were labeled with radio-active leucine. By radioautography, 96.2% of the radio-activity was present in megakaryocytes. The radio-active Factor VIII antigen present in the solubilized cell protein mixture was isolated by immunoprecipitation and characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The results demonstrate that cultured guinea pig megakaryocytes synthesize Factor VIII antigen which contains the same polypeptide subunit (mol wt 200,000) present in guinea pig plasma Factor VIII antigen.

Polyclonal Ig production after Epstein-Barr virus infection of human lymphocytes in vitro

Abstract: APART from the specific anti-Epstein-Barr virus (EBV) response in infectious mononucleosis (IM), there is a strong general increase of antibody levels1. The major increase comprises IgM. As EBV has been shown to infect B lymphocytes selectively2 we hypothesised that the virus triggered the infected cells to release immunoglobulin, much like the effect of certain B-cell mitogens3, although the mechanism of activation must be different. It is known that EBV infection in vitro of human blood lymphocytes gives rise to increased DNA synthesis4 and that lymphoid cell lines carrying the EBV genome shed or release immunoglobulins5 of various classes. Furthermore, the IgM increase seen in IM would fit with a polyclonal B-cell activation (PBA) of EBV as PBA usually gives rise to IgM secretion6. To test this hypothesis, we have exposed lymphocytes from cord blood and adult peripheral blood to EBV in vitro and measured the released IgM, by a doubleantibody radioimmunoassay, and individual antibody-forming cells (PFC) against haptenated red blood cells and sheep red blood cells (SRBC).

Histocompatibility antigen-activated cytotoxic T lymphocytes. II. Estimates of the frequency and specificity of precursors.

Abstract: Using limiting dilutions of responding cells in mouse mixed leukocyte cultures, we obtained direct estimates of the minimum frequency of precursors of cytotoxic T lymphocytes (CTL.P) for a variety of antigens. Depending on the strain combination, there were as many as 4-15 CTL.P reactive to DBA/2 among 10(4) lymph node cells. Taking into account that only 5-10% of peripheral T lymphocytes have the potential to develop into cytotoxic T lymphocytes (CTLs) (6), this implies that at least 1-2% of all CTL.P are responsive to any given H-2 haplotype difference. Precursors of cytotoxic cells thus have the same high frequency of cells reactive to alloantigens of the major histocompatibility complex as found among proliferating cells in graft-vs.-host reactions and mixed lymphocyte interactions. The frequencies of CTL.P reactive to xenoantigens (rat) or trinitrophenyl-modified self were less than half the frequency of alloreactive CTL.P. A minority of the CTL.P specific for one H-2 haplotype were also reactive to a third party H-2 haplotype, presumably on the basis of recognition of shared determinants. By dilution of sensitized cells from single microcultures, it was shown that a single CTL.P undergoes a minimum of three to four cell divisions and generates at least 8-16 CTLs after antigenic activation.

Hypothalamic changes during the immune response.

Abstract: The immune system is subject to an array of identified autoregulatory processes, but immunoregulation may also have a further basis in a network of immune-neuroendocrine interactions. Two antigens each produced an increase of more than 100% in electrical activity of individual neurones in the ventromedial but not in the anterior nucleus of the rat hypothalamus. Animals that failed to respond to antigen manifested no increase in the firing rate. These findings constitute the first evidence for a flow of information from the activated immune system to the hypothalamus, suggesting that the brain is involved in the immune response.

Lymphocyte Specificity to Protein Antigens: I. Characterization of the Antigen-Induced in Vitro T Cell-Dependent Proliferative Response with Lymph Node Cells from Primed Mice

Abstract: An in vitro assay which measures antigen-induced proliferation of primed murine lymph node cells is described. The response is mediated by T eclls since it can be obtained by using nylon wool-passed lymphocytes (less than 1% Ig+ cells) and it can be abolished by treatment with anti-Thy 1.2 and C. Furthermore, LN cells from nu/nu mice injected with antigen do not demonstrate antigen-induced proliferation in contrast to the response observed in euthymic littermate controls. Other relevant parameters of this proliferative assay include the observations that the response is highly antigen specific, can be seen as early as 4 days and as late as 60 days after in vivo priming, is restricted to the use of certain sets of LN when animals are injected subcutaneously at the base of the tail, and can be seen with LN cells from mice primed with antigen in either CFA or ICFA. The ease of the assay coupled with its specificity and quantitative dimensions provides a direct and simple method to evaluate processes involved in antigen-induced murine T lymphocyte activation.

Y-antigen killing by T cells of women is restricted by HLA.

Abstract: CYTOTOXIC T cells are important in graft rejection and in the control of virus infections, but the mode of interaction of these cells with their targets, particularly in man remains unclear. It has been shown in mice that products of genes in the major histocompatibility complex (H–2) are involved in these interactions even when the cytotoxic T cells are specific for viral or non-H–2 antigens. This involvement is seen as the requirements that the target cell must express the specific non-H–2 antigen and in addition the same H–2, D or K region antigens as were present on the cells which initiated the immune response1–4. Cytotoxic T cells specific for viral or non-H–2 antigens are thus restricted in the targets that they can kill by the H–2 antigens on the targets. For example, cytotoxic T cells from H–2b female mice suitably primed to the Y antigen of H–2b males, will only kill cells from male mice carrying an H–2D region derived from H–2b (refs 5,6). This report is to our knowledge the first clear demonstration that a similar restriction occurs in man. We describe a situation in man where cytotoxic reactions specific for non-HLA antigens can only occur when target cells carry both the HLA-A2 antigen of the original sensitising cell and the non-HLA target determinant(s). The strong association with maleness suggests that one of the specific antigens involved was coded for by the Y chromosome.

Cyclophosphamide-sensitive T lymphocytes suppress the in vivo generation of antigen-specific cytotoxic T lymphocytes

Abstract: Murine T lymphocytes sensitized in vitro against either allogeneic lymphocytes or syngeneic hapten-conjugated lymphocytes do differentiate into highly effective cytotoxic T lymphocytes (CTL) (1-3). In vivo immunization of T lymphocytes to the same antigens, however, results in the generation of only marginal cytotoxic activity (1,4,5). Recently we found that the weakness of in vivo generated cytotoxicity is not due to a failure of antigen-induced T-cell sensitization but rather due to suppression of the in vivo differentiation of sensitized CTL precursors into effective CTL(6). In keeping with this finding it was postulated that suppressor cells may regulate the in vivo differentiation of CTL. We now report, that cyclophosphamide-sensitive T cells suppress the in vivo differentiation of antigen-specific CTL. Thus, pretreatment of mice with a single dose of cyclophosphamide (100 mg/kg) converts their state of low responsiveness to a state of high responsiveness.

Augmentation of natural cytotoxic reactivity of mouse lymphoid cells against syngeneic and allogeneic target cells.

Abstract: The levels of natural cell-mediated cytotoxicity against tumor cells in young BALB/c and BALB/c nude mice could be augmented by inoculation of a variety of mouse tumor cells or of mouse thymocytes. In older mice with low levels of spontaneous cytotoxic reactivity, inoculation of tumor cells led to rapid appearance of cytotoxicity. This augmented cytotoxicity reached a peak 3 days after inoculation, and then declined rapidly. The specificity of the augmented cytotoxicity appeared to be the same as that seen with natural cell-mediated cytotoxicity. The detected antigens were restricted to mouse tumor cells and thymocytes, and were absent on cells from other species. The effector cells after boosting also had the same cell surface characteristics as the natural cytotoxic effector cells, being non-adherent, non-phagocytic, and only weakly sensitive to treatment with anti-theta serum plus complement. In addition to this boosting by mouse tumor cells, marked increases in the levels of cytotoxicity were caused by a variety of murine viruses, including murine sarcoma virus and lymphocytic choriomeningitis virus. These effector cells also had the same properties as those seen with natural cytotoxic effector cells. The results indicate that the levels of natural cell-mediated cytotoxicity in conventional and athymic BALB/c mice can be consistently and rapidly boosted by inoculation with tumor cells or viruses. This should provide a valuable tool for better understanding of the mechanisms responsible for the expression of natural cytotoxicity and its relevance to in vivo resistance to tumor growth.

Rabies virus glycoprotein. II. Biological and serological characterization.

Abstract: Purified rabies virus glycoprotein (G) was shown by complement fixation and immunodiffusion tests to be a second distinct antigen of the virus. It it the only structural protein of the virus that induces the formation of virus-neutralizing antibodies and which confers immunity to animals. When the G protein is taken as antigen, the complement fixation test can be used for the assay of virus-neutralizing antibodies. The total protective activity of the virus was recovered in the purified G protein preparation. The protective activity of G protein increased with purification: 9 ng of G protein was required to protect 50% of the mice as compared to 1.63 micrograms of the virus. Selective immunofluorescent membrane staining and immunocytolysis of rabies virus-infected cells were shown to be G protein specific. Due to its purity and potency, the G protein preparation can be considered the ideal human antirabies vaccine.

Antibody-dependent Killing of Erythrocyte and Tumor Targets by Macrophage-Related Cell Lines: Enhancement by PPD and LPS

Abstract: Five murine macrophage or monocyte-related tumor cell lines in culture were compared for antibody-dependent lysis (ADL) of a tumor target (T lymphoma EL4) and lysis and phagocytosis of sheep erythrocytes (RBC). Some lines were effective only with RBC targets, while others were capable of lysing these and tumor targets. Both murine alloantisera to H-2 and Thy 1.2 antigens on the target cells and rabbit anti-mouse spleen and anti-mouse thymus sera directed target lysis, while normal mouse or rabbit sera were inactive. Preincubation of macrophage line RAW264 with lipopolysaccharide (LPS) or purified protein derivative from Mycobacteria (PPD) for 2 days resulted in an average of 76% or 86% increase, respectively, in ADL of RBC, although there was no stimulation in RBC phagocytosis or in nonspecific or antibody-dependent lysis of tumor targets. These results indicate that macrophage cell types are capable of antibody-dependent tumor lysis, that macrophages are probably heterogeneous in effector cell activities, and that they can be stimulated to increased ADL in the complete absence of other cell types.

Hepatitis B e Antigen and Infectivity of Hepatitis B Virus

Abstract: For confirmation of the difference in the infectivity of hepatitis B surface antigen (HBS Ag)-positive serum according to differences in the e antigen system, four chimpanzees were inoculated with serum positive for hepatitis B e antigen (HBe Ag), and three chimpanzees were inoculated with serum positive for antibody to HBe Ag (anti-HBe). Since the infectivity titrations are not yet completed, the end infectivity titer of each serum is not known. All four chimpanzees given injections of 10(-1), 10(-4), or 10(-8) dilutions of HBe Ag-positive serum developed hepatitis B virus infection, whereas the one chimpanzee injected with undiluted anti-HBe-positive serum became infected, and other chimpanzees injected with diluted anti-HBe-positive sera did not. As judged from the length of the incubation period before appearance of HBS Ag in blood, there seemed to be a remarkable difference in infectivity between the HBe Ag-positive serum and the anti-HBe-positive serum; the former serum was 10(8) times more infectious than the latter.

HLA restriction of cell-mediated lysis of influenza virus-infected human cells.

Abstract: MURINE T lymphocytes that mediate the lysis of virus-infected cells show specificity both for the viral cell surface antigens and for the H–2K or D antigens of the major histo-compatibility complex1–8. The cytotoxic T lymphocytes and the target cell must share H–2K or D products. The experiments reported here demonstrate that there is a similar requirement for partial HLA identity between human cytotoxic lymphocytes and influenza virus-infected target cells.

Surface differentiation antigens of human mammary epithelial cells carried on the human milk fat globule

Abstract: Rabbit antibodies against components of the human milk fat globule bind specifically to normal human breast epithelial cells and cell lines derived from breast carcinomas, as well as to the outer surface of the human milk fat globule. Variation in indirect immunofluorescence staining in both intensity per cell and percentage of cells stained is observed for the different brest cell lines. Cells derived from other epithelial and other ectodermal tissues, fetal fibroblasts, cells of the blood buffy coat, and even fibroblasts of the breast itself do not bind the antibodies. This suggests that these antibodies are detecting cell-type-specific antigens. These normal breast epithelial cell antigens are on the cell surface and their expression is stable in long-term cultured cell lines, even after much chromosomal variation in a given line. By affinity chromatography, three distinct antigenic components can be isolated from the milk fat globule, one of which contains carbohydrate. These differentiation antigens of the human breast epithelial cell are not only useful as specific cell-type markers, but also can provide a tool to study the role of the cell surface in normal and neoplastic mammary development.

Mechanism of Specific Tumor-Cell Lysis by Alloimmune T Lymphocytes: Resolution and Characterization of Discrete Steps in the Cellular Interaction

Abstract: A cytolytic thymus-derived lymphocyte (CTL)* is a specialized cell the recognized function of which is immune killing. CTLs are generated by a process of antigen-induced clonal selection, proliferation, and differentiation. Each CTL apparently recognizes a single H-2 alloantigen. CTL targets are eukaryotic tissue cells bearing specific membrane-associated antigen, such as virus-infected autologous cells, grafted cells of genetically different origin, tumor cells, or autologous cells made more immunogenic by chemical modification. CTLs are believed to play a uniquely important role in physiological immune tissue destruction (for which serum immunoglobulins are usually insufficient), probably utilizing mononuclear phagocytes as an amplifying mechanism.