Showing papers on "Antigen published in 1982"

Synthesis and assembly of hepatitis B virus surface antigen particles in yeast

Abstract: The surface antigen of hepatitis B virus (HBsAg) has been synthesized in the yeast Saccharomyces cerevisiae by using an expression vector that employs the 5′-flanking region of yeast alcohol dehydrogenase I as a promoter to transcribe surface antigen coding sequences. The protein synthesized in yeast is assembled into particles having properties similar to the 22-nm particles secreted by human cells.

Production of a monoclonal antibody specific for Hodgkin and Sternberg–Reed cells of Hodgkin's disease and a subset of normal lymphoid cells

Abstract: The origins of the neoplastic cells in Hodgkin's lymphoma1, the Hodgkin (H) and Sternberg–Reed(SR) cells, are still obscure, and these cells appear to carry no markers found on any population of normal cells2,3. However the recent establishment of permanent Hodgkin cell lines3,4 has led to the search for tumour-specific antigens and/or for membrane markers on H and SR cells which may indicate the normal equivalent cells. Here, we describe the production of mouse monoclonal antibodies against the Hodgkin cell line L428. One hybridoma antibody, Ki-1, was found to be specific for H and SR cells of all Hodgkin's lymphomas tested and a minute, but distinct new cell population in normal tonsils and lymph nodes.

Restoration of immunogenicity to passenger cell-depleted kidney allografts by the addition of donor strain dendritic cells.

Abstract: The immunogenicity of long-surviving, enhanced (AS X AUG)F1 renal allografts retransplanted into secondary AS recipients was restored by the injection of small numbers of donor strain dendritic cells derived from afferent lymph. Whereas 1 X 10(4) to 5 X 10(4) dendritic cells were able to trigger an acute rejection response, neither the passenger volume of donor strain blood nor 5 X 10(6) T or B lymphocytes were able to do so, thereby demonstrating more than a 100-fold difference in immunogenic potency. It is concluded that intrarenal dendritic cells provide the major immunogenic stimulus of a kidney allograft. These results suggest that the antigenic strength of major histocompatibility complex-incompatible tissue correlates with the content of donor strain dendritic cells. They also provide further evidence that antigens of the major histocompatibility complex behave like conventional antigens unless they are on the surface of allogeneic dendritic cells.

A monoclonal antibody that appears to recognize the receptor for human T-cell growth factor; partial characterization of the receptor

Abstract: T-cell growth factor (TCGF or interleukin-2) is an inducible glycoprotein hormone of molecular weight 15,000 (ref. 1) synthesized and secreted by T lymphocytes following activation with antigen or mitogen2,3. TCGF is required for proliferation and expansion of T cells following antigen encounter4,5 and to maintain them in long-term culture in vitro6–9. Full expression of the human immune response requires both the induction of TCGF synthesis and the formation of specific TCGF membrane receptors10,11. Monoclonal antibodies binding TCGF have been prepared12,13. In contrast, antibodies specific for the TCGF membrane receptor have not been identified, nor has the receptor been characterized. We have prepared a monoclonal antibody, termed anti-Tac14,15, which appears to bind to the human membrane receptor for TCGF. In support of this, we now demonstrate that anti-Tac suppresses TCGF induced proliferation of T cells and blocks binding of radiolabelled TCGF to cells from a cloned human continuous T-cell line. Also we have partially purified and characterized the putative TCGF receptor. This receptor is a glycoprotein with a molecular weight (Mr) of 47,000–53,000.

Three distinct antigens associated with human T-lymphocyte-mediated cytolysis: LFA-1, LFA-2, and LFA-3.

Abstract: Monoclonal antibodies were prepared to anti-HLA-DR cytolytic T lymphocytes (CTLs) and screened for inhibition of CTL-mediated killing. Binding of monoclonal antibodies to four types of molecules, LFA-1, LFA-2, LFA-3, and HLA-DR, inhibited killing, suggesting that these molecules participate in the CTL-target cell interaction. The antigens were characterized by immunoprecipitation, crosslinking, NaDodSO4/polyacrylamide gel electrophoresis, and immunofluorescence flow cytometry. The LFA-1 antigen contains alpha and beta polypeptide chains of Mr 177,000 and 95,000 that are noncovalently associated in an alpha 1 beta 1 structure. It is present on both B and T lymphocytes and marks subpopulations that differ in quantitative expression. Human LFA-1 appears to be the homologue of mouse LFA-1. Human LFA-2 is of Mr 49,000 with a minor component of Mr 36,000. It is expressed on CTL lines but not on a B-cell line and in peripheral blood preferentially on T lymphocytes. Human LFA-3 is of Mr 60,000 and is expressed on both B and T lymphocytes.

Corticosteroids inhibit murine macrophage Ia expression and interleukin 1 production.

Abstract: Corticosteroids have profound effects on functions of the macrophage associated with antigen presentation to T cells. The drugs inhibited the expression of surface I-region-associated (Ia) antigens by peritoneal macrophages both in vitro and in vivo, reduced the production of IL 1, and inhibited antigen presentation for T cell proliferation by macrophages. The doses of hydrocortisone and prednisolone that inhibited by 50% Ia expression in cultured macrophages ranged around 2 to 5 x 10(-8) M. These results could explain one mechanism by which corticosteroids suppress the induction of immune responses.

Cytotoxic t cells in cytomegalovirus infection: HLA-restricted T-lymphocyte and non-T-lymphocyte cytotoxic responses correlate with recovery from cytomegalovirus infection in bone-marrow-transplant recipients.

Abstract: We studied 58 recipients of bone-marrow transplants to evaluate immune responses to cytomegalovirus infection. Such infection developed in 43 patients; it was fatal in 12, nonfatal in 23, and present at death from other causes in eight. All patients had low or absent cytomegalovirus-specific cytotoxic lymphocyte activity before the onset of infection. Cytomegalovirus-specific cytotoxic responses developed in all survivors, whereas only two patients with fatal infection had even low-level cytomegalovirus-specific cytotoxic responses. Natural and antibody-dependent killer-cell activities were depressed both before and during infection in patients with fatal infections, but not in those who survived. The outcome of the infection did not correlate with the nature of the underlying disease, the type of transplant received, the pretransplantation cytomegalovirus-antibody status, or lymphocyte-proliferation responses to cytomegalovirus antigens or concanavalin A. The correlation between effective virus-specific cytotoxic response and recovery from infection indicates that these effector cells probably mediate recovery from cytomegalovirus infection.

Anti-Mac-1 selectively inhibits the mouse and human type three complement receptor.

Abstract: Anti-Mac-1 (M1/70), a rat monoclonal antibody that reacts with mouse and human macrophages, polymorphonuclear leukocytes (PMNL), and natural killer cells, selectively inhibited complement receptor-mediated rosetting by murine macrophages and human PMNL. Preincubation of macrophages with anti-Mac-1 inhibited formation of rosettes with sheep erythrocytes bearing IgM antibody and murine C3 fragments. No inhibition was observed when other monoclonal antibodies that react with macrophages (such as anti-Ly5, anti-H-2, or anti-pan-leukocyte) were tested at 10-fold higher concentrations. Anti-Mac-1 did not affect macrophage Fc receptor-mediated rosetting. Erythrocytes bearing homogeneous human C3 fragments C3b (EC3b) or C3bi (EC3bi) were used to test the specificity of the murine macrophage and human PMNL complement receptor inhibited by anti-Mac-1. In both cases, anti-Mac-1 inhibited CR3-mediated rosetting of EC3bi but not CR1-dependent rosetting of EC3b. The results show that Mac-1 is either identical to CR3 or closely associated with CR3 function. This is one of the first cases in which a monoclonal antibody-defined differentiation antigen has been associated with a specific cell surface function.

Autoantibodies in newly diagnosed diabetic children immunoprecipitate human pancreatic islet cell proteins

Abstract: Insulin-dependent diabetic (IDD) patients have a high prevalence of circulating autoantibodies against islet of Langerhans cells at the time of diagnosis1–4. Inflammatory cells within the islets5, leukocyte migration inhibition in response to pancreatic antigens6 and an association with certain HLA-D/DR histocompatibility antigens7,8, have also been observed. It seems that the autoantibodies may be pathogenically relevant as they react primarily with β-cells9, but the specific target antigen(s) have yet to be identified. In the present study we determined whether sera from insulin-dependent diabetic children are able to immunoprecipitate proteins from detergent lysates of human islet cells. We report that sera from 8 out of 10 newly diagnosed diabetic children consistently immunoprecipitate a protein having a molecular weight (M r) of 64,000 (64K). An additional protein (38K) was precipitated from islet cells obtained from a HLA-DR3-positive donor. Neither of the proteins was precipitated by non-diabetic sera nor detected in immunoprecipitates from human lymphocyte lysates. It is suggested that the 64K and/or 38K protein components may represent cell-specific target antigens in insulin-dependent diabetes.

GD3, a prominent ganglioside of human melanoma. Detection and characterisation by mouse monoclonal antibody.

Abstract: Mouse monoclonal antibody AbR24 has a high degree of specificity for human melanoma cells when tested on viable cultured cells using the protein A mixed hemagglutinin serological assay. The antigen detected by this antibody has been isolated from melanoma cells and shown to be GD3 ganglioside by compositional and partial structural analysis and by comparison with authentic GD3 in thin layer chromatography (TLC). AbR24 reacts with authentic GD3, but not with any other ganglioside tested. Using TLC and reactivity with AbR24, a wide range of cells and tissues was examined for the presence of GD3. A new serological assay, termed glycolipid-mediated immune adherence, was devised for assaying the reactivity of AbR24 with gangliosides. Melanomas (cultured cells or tumor tissue) were shown to have GD3 and GM3 as major gangliosides. Other cells and tissues examined also contained GD3, but usually only in low amounts. Melanomas (and MOLT-4, a T cell line) were characterized by a simplified ganglioside profile with GD3 and GM3 as major components. The apparent discrepancy between the ubiquitous presence of GD3 and the serological specificity of AbR24 for melanoma cells can be explained in terms of localization and concentration of GD3 in different cells.

Recombinant monoclonal antibodies

Abstract: Antibodies having binding affinity for two desired antigens, hereinafter "recombinant monoclonal antibodies"; recombinant monoclonal antibodies produced by a quadroma cell or a trioma cell; and methods for producing recombinant monoclonal antibodies by means of a quadroma cell or a trioma cell, wherein a quadroma cell is the fusion product of a hybridoma cell which produces an antibody having specific binding affinity to one desired antigen and a hybridoma cell which produces an antibody having specific binding affinity for another desired antigen, and wherein a trioma cell is the fusion product of a hybridoma cell which produces an antibody having specific binding affinity to one desired antigen and a lymphocyte which produces an antibody having specific binding affinity to another desired antigen.

Clonal analysis of human cytotoxic T lymphocytes: T4+ and T8+ effector T cells recognize products of different major histocompatibility complex regions.

Abstract: Alloreactive human T lymphocytes were cloned in soft agar or by limiting dilution and subsequently propagated with interleukin 2 and alloantigen for 8 months or more By indirect immunofluorescence every clone was reactive with anti-Ia antibodies as well as the T cell-specific antibodies anti-T3 and anti-T11 and expressed either T4 or T8 antigens All 15T8+ clones were highly cytotoxic for the sensitizing alloantigen In contrast, only two of seven T4+ clones mediated cytotoxic effector function The specificity of T4+ and T8+ clones and subclones was analyzed on a panel of typing cells and by antibody blocking studies of major histocompatibility complex (MHC) determinants on the stimulating alloantigen It was found that T8+ clones killed targets that shared class I MHC antigens (HLA-A,B) with the original stimulator cells whereas cytotoxic T4+ clones were directed at class II MHC antigens (Ia-related) Preincubation of the allogeneic target cell with a monoclonal antibody to a nonpolymorphic HLA alpha-chain determinant inhibited killing by the T8+ clones but did not affect T4+ cytotoxic function In a reciprocal fashion, anti-IA antibodies to common framework structures on the same target cell blocked killing by T4+ but not by T8+ clones These results indicate that T4+ and T8+ T lymphocytes have receptors for different classes of MHC antigens and suggest tha cytotoxic T4+ subpopulations might be important in human transplantation and autoimmune disorders

Human Neutrophil Fc Gamma Receptor Distribution and Structure

Abstract: Fc receptors (FcR) for IgG on human cells were analyzed with two monoclonal antibodies, 3G8 and 4F7. Fab fragments of both hybridoma IgGs inhibited binding to neutrophils of soluble rabbit IgG complexes and sheep erythrocytes (E) coated with rabbit IgG. The number of sites for 3G8 Fab was 135,000 per neutrophil, roughly equivalent to the number of sites for rabbit IgG in immune complexes (112,000 per cell). We did not observe human IgG1 binding sites on neutrophils, although binding of IgG1 to FcR-bearing lines U937 and HL-60 was readily demonstrated. Other cell types bearing 3G8 binding sites were mature chronic myelogenous leukemia cells, eosinophils, 6% of E-rosetting lymphocytes, and 15% of Ig-bearing peripheral lymphocytes. No binding of 3G8 Fab was observed on the FcR-bearing cell lines U937, HL-60 Raji, Daudi, and K562 or on blood monocytes. However, 15% of monocytes cultured for 7 days and 60% of lung macrophages expressed 3G8 antigen. When analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis, the neutrophil FcR immunoprecipitated with 3G8 or 4F7 Fab-Sepharose displayed a broad band extending from Mr 73,000 to 51,000; in many experiments this band was resolved into two poorly separated components, centered at Mr 66,000 and 53,000. These results show that human neutrophil FcR for IgG is different from that on monocytes, with respect to both antigenic composition and binding of monomeric IgG1.

Decrease in macrophage antigen catabolism caused by ammonia and chloroquine is associated with inhibition of antigen presentation to T cells

Abstract: This paper describes the effects of two lysosomotropic compounds, ammonia and chloroquine, on the interaction of mononuclear phagocytes with immune T cells. The uptake and ingestion of Listeria monocytogenes by macrophages were not affected by the drugs; however, the macrophage catabolism of 125I-labeled Listeria was reduced in a dose-dependent way. The macrophage presentation of Listeria to T cells, an I-region-dependent phenomenon, was also inhibited. The degree of inhibition of catabolism paralleled that of antigen presentation. The inhibition of antigen presentation took place if the macrophages were treated before and during Listeria uptake; minimal inhibition took place if the macrophages were treated 30 min after Listeria ingestion, at which time a significant amount of bacteria was already catabolized. Our previous studies had shown that the macrophage-associated antigen recognized by T cells became apparent 30-60 min after uptake of Listeria. We conclude that ammonia and chloroquine affected an intracellular handling step required for the expression of the immunogen relevant for T-cell recognition.

Helper activity is required for the in vivo generation of cytotoxic T lymphocytes

Abstract: B6.T1a(a) (Qa-1(a)) mice that are primed in vivo and restimulated in vitro with Qa-1 congenic spleen cells from B6 (Qa-1(b)) animals are unable to generate anti-Qa-1(b) cytotoxic T lymphocytes (CTL). This nonresponsive pattern was observed regardless of the route of immunization or the time of testing in vitro. Although B6.T1a(a) mice are nonresponders to Qa-1(b) when presented on B6 cells, these mice can generate anti-Qa-1(b) CTL when primed in vivo with Qa-1 and H-Y alloantigens (females primed with B6 male cells) or Qa-1 and minor-H- alloantigens (primed with sex-matched A.BY cells). Therefore, the inability to generate anti-Qa-1(b) CTL is due to a lack of helper or accessory antigens on B6 immunizing cells obligatory during in vivo priming, rather than an absence of anti-Qa-1(b) CTL precursors (CTL-P). Demonstration that the additional determinants required during in vivo priming actually function as carrier or helper determinants was shown by the requirement for linked recognition of Qa-1 and the helper determinants (H-Y) in vivo, and the fact that H-Y was not present on susceptible target ceils. Animals primed in vivo with H-Y only could not generate anti-Qa-1 CTL activity when challenged in vitro with both Qa-1 and H-Y, indicating that recognition of the helper determinant causes in vivo priming of CTL-P rather than generating helper activity that might activate unprimed CTL-P in vitro. Whereas unprimed peripheral CTL-P require the presence of both Qa-1 (CTL) and H-Y (helper) determinants for successful in vivo priming, helper determinants were not required in vitro because primed CTL-P from B6.T1a(a) mice could be driven to CTL in vitro using sex-matched B6 stimulator cells. The generation of anti-Qa-1(b) CTL is under immune response (Ir) gene control because F(1) mice, obtained by crossing responder A/J with nonresponder B6.T1a(a) animals, generated CTL to the Qa-1(b) alloantigen when presented on B6 spleen cells. Progeny testing of backcross mice further demonstrated that the Ir gene(s) is linked to the H-2 complex. These data indicate that an H-2-linked Ir gene controls the recognition of helper determinants required for CTL priming in vivo. These helper determinants can be distinguished from CTL determinants and both must be recognized together for successful priming of CTL-P.

Monoclonal antibodies against the Drosophila nervous system

Abstract: A panel of 148 monoclonal antibodies directed against Drosophila neural antigens has been prepared by using mice immunized with homogenates of Drosophila tissue. Antibodies were screened immunohistochemically on cryostat sections of fly heads. A large diversity of staining patterns was observed. Some antigens were broadly distributed among tissues; others were highly specific to nerve fibers, neuropil, muscle, the tracheal system, cell nuclei, photoreceptors, or other structures. The antigens for many of the antibodies have been identified on immunoblots. Monoclonal antibodies that identify specific molecules within the nervous system should prove useful in the study of the molecular genetics of neural development.

Tumor-specific antigen of murine T-lymphoma defined with monoclonal antibody.

Abstract: A panel of hybridomas was constructed by fusion of P3X63Ag8 myeloma cells with spleen cells from a BALB/c mouse that had been immunized with a C57BL/Ka x-ray-induced lymphoma, C6XL. One of forty-three hybridomas secreting antibodies reactive with the tumor cells was found to be unreactive with normal spleen cells in a radioimmunometric assay. This antibody, designated 124-40, was unreactive with normal adult thymus, spleen, lymph node, or bone marrow cells, or with fetal spleen or thymus cells in radioimmunometric or radioimmunoprecipitation assays. Flow microfluorometric analysis of these nonmalignant lymphoid cells failed to reveal subpopulations reactive with MAb 124-40. The antibody was highly specific for the lymphoma cells used for immunization and did not react with a panel of other spontaneous or x-ray-induced or chemically induced lymphomas. The antigen reactive with MAb 124-40 was isolated by radioimmunoprecipitation and found to be a glycoprotein composed of disulfide-bonded subunits of 39,000 m.w. and 41,000 m.w. A cell surface component of similar structure, but not reactive with MAb 124-40 could be detected by two-dimensional electrophoresis in extracts of purified T cells, but not B cells. These results suggest that the apparently individually specific lymphoma antigen reactive with MAb 124-40 might be a clonally expressed epitope carried by a T cell surface component.

Infrequent normal B lymphocytes express features of B-chronic lymphocytic leukemia.

Abstract: An infrequent (2-3%) B lymphocyte subpopulation was found in the normal human tonsil and lymph nodes that shows the phenotypic characteristics of B-chronic lymphocytic leukemia (B-CLL) (rosette formation with mouse erythrocytes, weak expression of membrane Ig, staining for HLA-DR, and OKT1 or Leu-1 detecting a T cell-associated p65 antigen). Preliminary evidence suggests that at least a subpopulation of these cells is found, in small proportions, within the germinal centers. These cells were not observed in the human bone marrow. B-CLL may involve this peripheral B lymphocyte subset.

Antibody conjugates for the delivery of compounds to target sites

Abstract: A method is described for the covalent attachment of linker groups to specific sites on antibody molecules directed against any desired target antigen (tumor, bacterial, fungal, viral, parasitic etc.). These linkers can be attached via amide or ester bonds to compounds for delivery which contain available amino or hydroxy groups (e.g., bioactive agents, cytotoxic agents, dyes, fluors, radioactive compounds, etc.). In addition the linkers can be incorporated into insoluble matrices for use in separation schemes which are based upon antibody-antigen interactions. The linkers may be designed so that they are susceptible to cleavage by any one of the serum complement enzymes. When prepared according to the methods described herein, the resulting modified antibody molecule retains the ability to bind antigen and to fix serum complement. Thus, when administered to a patient the antibody conjugate binds to its target in vivo. As a result of the subsequent activation of the patient's serum complement, the covalently attached compound will be specifically cleaved at the target site by the proteolytic enzymes of the complement system.

Monoclonal antibodies provide specific intramolecular markers for the study of epithelial tonofilament organization.

Abstract: The tonofilament-associated protein antigens recognized in epithelial cells by a group of six monoclonal antibodies have been studied by immunofluorescence and gel immunoautoradiography. The monoclonal antibodies were generated against detergent insoluble cytoskeleton extracts from a cultured simple epithelium derived cell line, Ptk1 cells. They show various tissue specificities, and while they all recognize components at the low end of the molecular weight range for intermediate filament proteins, they confirm that single antibody species can react with multiple polypeptides of different molecular weights in the tonofilament complex. The monoclonal antibodies described here demonstrate the presence of a simple epithelium antigenic determinant associated with intermediate filaments that is not detectable in the specialized cells of squamous and keratinizing epithelia but can reappear in such cells after transformation.

Regulation of murine macrophage Ia antigen expression by a lymphokine with immune interferon activity.

Abstract: A culture supernatant of concanavalin A-activated spleen cells (Con A supernatant) induced murine macrophages to express Ia antigens in vitro. Biochemical characterization of the Con A supernatant indicated that the macrophage Ia antigen regulatory activity shares molecular weight, pI, and hydrophobic and affinity characteristics with immune interferon (IFN-gamma). Antiserum to mouse IFN-gamma neutralized both the macrophage Ia antigen regulatory and IFN-gamma bioactivities of the Con A supernatant. Furthermore, both partially purified murine IFN-gamma (10(7) U/mg protein sp act) and IFN-containing culture supernatants of the murine BFS T cell line-induced macrophage Ia antigen expression in vitro. Culture supernatants containing colony-stimulating factor, interleukin 1, interleukin 2, macrophage migration inhibitory factor, and a macrophage-activating activity that were distinct from IFN-gamma did not induce macrophage Ia antigen expression. Taken together, the data indicate that the in vitro expression of Ia antigens on macrophages is regulated by an activity that has the characteristics of interferon.

Monoclonal antibodies to mouse major histocompatibility complex antigens.

Abstract: As part of our continuing effort to produce a library of hybridoma antibodies specific for the products of the mouse major histocompatibility complex (MHC), nine antibodies reacting with antigens of the H-2d haplotype have been produced by cell fusion between immune spleen cells and the SP2/0.Ag.14 cell, of H-2d origin. Serological characterization revealed that seven antibodies reacted with H-2 antigens and two with Ia antigens. Of the anti-H-2 antibodies, four detected private specificities of H-2Kd or H-2Dd antigens and three detected public specificities of H-2d and other haplotypes. One of the anti-Ia antibodies detected a private Ia specificity corresponding to Ia.23 and the other detected a previously undescribed public specificity. Anti-H-2d hybridoma cells represent a potential "autoreactive" situation in that the antibodies produced by the cells should react with their own H-2 antigens unless expression of the corresponding H-2d antigens in these cells was altered. In order to examine whether H-2d antigens continued to be expressed on these anti-H-2d hybridoma cells, binding of 125I-labeled monoclonal anti-H-2Kd and/or H-2Dd antibodies was studied. Among the four hybridoma clones tested, three bound specifically three independent 125I-labeled anti-H-2d antibodies, including two cases in which binding of autologous antibodies was detected. The last clone did not bind any of the anti-H-2d antibodies, although it bound an anti-H-2k antibody, indicating selective loss of H-2d antigens. These observations demonstrate that neither loss nor retention of H-2d antigen expression on the cell surface is obligatory in hybridoma cells producing anti-H-2d antibodies.

Mac-2, a novel 32,000 Mr mouse macrophage subpopulation-specific antigen defined by monoclonal antibodies.

Abstract: Two monoclonal antibodies, M3/31 and M3/38, were obtained by fusion of mouse myeloma cells with rat spleen cells immunized to immunoadsorbent-purified macrophage glycoproteins. Co-precipitation experiments show that antigenic determinants recognized by these two antibodies reside on the same molecular species, termed Mac-2, Mac-2, an antigen of 32,000 Mr, is synthesized by and expressed on the surface of thioglycollate-elicited macrophages as shown by [35S]-methionine and 125I labeling. Saturation binding experiments show that thioglycollate-elicited macrophages express 1.7 X 10(5) Mac-2 sites/cell. Thioglycollate-elicited macrophages are strongly absorptive for 125I-labeled M3/38 MAb. Kidneys are also absorptive; however, evidence is presented pointing to the nonspecificity of this absorption. Lymph node and thymus are negative, whereas spleen and bone marrow are weakly absorptive, probably due to stromal cells. Nonlymphoid tissues, such as lung, liver, heart, and brain, exhibit slight or no absorbing capacity. Cell suspensions from spleen, bone marrow, thymus, and peripheral lymph node are greater than 99% Mac-2- by immunofluorescent flow cytometry. In contrast, thioglycollate-elicited macrophages are greater than 96% strongly positive for Mac-2. Only 20% of peptone-elicited cells are weakly positive, whereas resident peritoneal macrophages and other macrophage elicited by Listeria monocytogenes, Con A, or LPS are greater than 98% negative. SDS-PAGE of [35S]-methionine-labeled Mac-2 shows that thioglycollate-elicited macrophages synthesize 10- to 30-fold more Mac-2 than other peritoneal macrophage subpopulations, whereas all types of peritoneal macrophages synthesize and express on their surfaces similar amounts of the Mac-1 antigen. Mac-2 antigen is therefore induced in macrophages only in response to specific differentiative signals.

Gastrointestinal cancer-associated antigen in immunoperoxidase assay.

Abstract: A monosialoganglioside antigen of gastrointestinal adenocarcinomas defined by murine monoclonal antibody was demonstrated by immunoperoxidase (IP) assay in fixed paraffinembedded tumors in 59% of colonic adenocarcinomas, 86% of pancreatic adenocarcinomas, and 89% of all gastric adenocarcinomas. In all patients with detectable levels of antigen in circulation, the resected tumors also expressed the antigen in IP assay. Six of eight individuals with no detectable levels of antigen in their serum samples expressed the antigen in the tumor tissue. Removal of the sialic acid residue of the antigen abolished the IP reaction. The successful use of the IP assay on fixed tissue to demonstrate the specific sites of gastrointestinal cancer antigen localization in human tumors and normal tissues provides an important tool for the study of developing neoplasia.