Showing papers on "Antibody published in 1986"

Complementary DNA for a novel human interleukin (BSF-2) that induces B lymphocytes to produce immunoglobulin

Abstract: When stimulated with antigen, B cells are influenced by T cells to proliferate and differentiate into antibody-forming cells. Since it was reported that soluble factors could replace certain functions of helper T cells in the antibody response, several different kinds of lymphokines and monokines have been reported in B-cell growth and differentiation. Among these, human B-cell differentiation factor (BCDF or BSF-2) has been shown to induce the final maturation of B cells into immunoglobulin-secreting cells. BSF-2 was purified to homogeneity and its partial NH2-terminal amino-acid sequence was determined. These studies indicated that BSF-2 is functionally and structurally unlike other known proteins. Here, we report the molecular cloning, structural analysis and functional expression of the cDNA encoding human BSF-2. The primary sequence of BSF-2 deduced from the cDNA reveals that BSF-2 is a novel interleukin consisting of 184 amino acids.

Overlapping patterns of activation of human endothelial cells by interleukin 1, tumor necrosis factor, and immune interferon.

Abstract: We have used the quantitative binding of murine monoclonal antibodies to the surface of cultured human umbilical vein endothelial (HUVE) cells to study the responses of HUVE cells to three different immune mediators: interleukin 1 (IL 1), tumor necrosis factor (TNF), and immune interferon (IFN-gamma) Antibody H4/18, reactive with an endothelial cell-specific activation antigen, does not bind to unstimulated HUVE cells but shows rapidly and transiently inducible binding (peak 4 to 6 hr) to cells stimulated by IL 1 or TNF that declines to basal levels by 24 hr, even in the continued presence of mediator Binding of H4/18 is unaffected by IFN-gamma Antibody RR1/1, reactive with intercellular adhesion molecule 1, binds to unstimulated HUVE cells, but binding is rapidly increased (plateau 24 hr) after stimulation by IL 1 or TNF and slowly increased (over several days) by IFN-gamma In contrast to H4/18 binding, the increase in RR1/1 binding is sustained in the continued presence of mediator Antibody W6/32, reactive with HLA-A,B antigens, binds to unstimulated HUVE cells and shows gradually progressive increases (over several days) in binding upon treatment with IFN-gamma or TNF These observations demonstrate that HUVE cells show distinct but overlapping patterns of antigenic modulation in response to three different lymphokines, and suggest that the "activation" of endothelial cells observed in situ may represent a complex integration of several lymphokine-mediated signals

Regional accumulations of T cells, macrophages, and smooth muscle cells in the human atherosclerotic plaque.

Abstract: The cellular composition of human atherosclerotic plaques was analyzed by immunologic techniques. Plaques were removed from the internal carotid artery during surgery, and a panel of monoclonal antibodies was used to identify cell types. Macrophages stained by Anti-Leu-M3 were found throughout the plaque, particularly in the lipid core region, where 60% of the cells reacted with this antibody. T cells expressing the T3 antigen were most abundant in the fibrous cap, where they constituted 20% of the cell population. T cells were also isolated from the plaque and detected by a rosetting test; many of these T cells were activated, as indicated by the expression of HLA-DR. Other types of leukocytes were uncommon in the plaque. An antibody to the intermediate filament protein, desmin, was used as a marker for smooth muscle cells since some, but not all, vascular smooth muscle cells contain this protein. The desmin-positive cells were uncommon in the nonatherosclerotic intima but were more numerous in the plaque. In conclusion, atherosclerotic plaques are heterogeneous with respect to cellular composition. The smooth muscle cell dominates in the fibrous cap, which also contains many T cells; the lipid core is dominated by macrophages. We suggest that interactions between smooth muscle cells and blood-borne cells are important in the pathogenesis of atherosclerosis.

Binding of HTLV-III/LAV to T4+ T cells by a complex of the 110K viral protein and the T4 molecule.

Abstract: Human T-lymphotropic virus type III (HTLV-III) or lymphadenopathy-associated virus (LAV) is tropic for human T cells with the helper-inducer phenotype, as defined by reactivity with monoclonal antibodies specific for the T4 molecule. Treatment of T4+ T cells with monoclonal antibodies to T4 antigen blocks HTLV-III/LAV binding, syncytia formation, and infectivity. Thus, it has been inferred that the T4 molecule itself is a virus receptor. In the present studies, the surfaces of T4+ T cells were labeled radioactively, and then the cells were exposed to virus. After the cells were lysed, HTLV-III/LAV antibodies were found to precipitate a surface protein with a molecular weight of 58,000 (58K). By blocking and absorption experiments, this 58K protein was identified as the T4 molecule. No cell-surface structures other than the T4 molecule were involved in the antibody-antigen complex formation. Two monoclonal antibodies, each reactive with a separate epitope of the T4 molecule, were tested for their binding capacities in the presence of HTLV-III/LAV. When HTLV-III/LAV was bound to T4+ T cells, the virus blocked the binding of one of the monoclonal antibodies, T4A (OKT4A), but not of the other, T4 (OKT4). When HTLV-III/LAV was internally radiolabeled and bound to T4+ T cells which were then lysed, a viral glycoprotein of 110K (gp110) coprecipitated with the T4 molecule. The binding of gp110 to the T4 molecule may thus be a major factor in HTLV-III/LAV tropism and may prove useful in developing therapeutic or preventive measures for the acquired immune deficiency syndrome.

B cell stimulatory factor-1 enhances the IgE response of lipopolysaccharide-activated B cells.

Abstract: Supernatants from some mouse helper T cell (TH) lines contain an activity that can enhance IgE production by lipopolysaccharide (LPS)-stimulated B cells by at least two orders of magnitude. During purification, this activity could not be resolved from B cell stimulatory factor-1 (BSF-1). Highly purified BSF-1 from a different source, the T lymphoma cell line EL-4, enhanced IgE production to the same extent as TH supernatants, which suggests that BSF-1 is responsible for this increase in IgE production. Monoclonal antibody to BSF-1 totally inhibits the IgE-enhancing activity of a TH supernatant, lending further support to this conclusion. The effects of BSF-1 on LPS-stimulated B cells are specific for IgE and, as previously reported, IgG1 and IgG3, because the levels of IgM, IgG2a, IgG2b, and IgA in the cultures change relatively little when BSF-1 is added.

A T cell activity that enhances polyclonal IgE production and its inhibition by interferon-gamma.

Abstract: The addition of concanavalin A-stimulated supernatants of the helper T cell clone, D9.1, to cultures of lipopolysaccharide (LPS)-stimulated T-depleted mouse spleen cells caused more than a 100-fold increase in immunoglobulin (Ig) E production. These supernatants cause a 10-fold to 15-fold increase in IgG1, a fivefold to 10-fold increase in IgA, and a fivefold to 10-fold decrease in IgG3. These effects are optimal when the supernatants are added 1 to 2 days after stimulation with LPS. Cells from mouse strains that normally give little or no IgE response in vivo give normal IgE levels in response to LPS plus the supernatant of Concanavalin A-stimulated D9.1 cells in vitro. The enhancement of both IgE and IgG1 can be completely inhibited by relatively low concentrations of interferon-gamma (IFN-gamma). Both the IgE-enhancing activity and IFN-gamma act directly upon purified B cells.

Macrophage heterogeneity in the rat as delineated by two monoclonal antibodies MRC OX-41 and MRC OX-42, the latter recognizing complement receptor type 3.

Abstract: Two monoclonal antibodies, designated MRC OX-41 and MRC OX-42, have been shown to label subsets of macrophages. Using immunoperoxidase and immunofluorescence analysis, tissue macrophages were shown to be heterogeneous with respect to binding of MRC OX-41 and MRC OX-42 antibodies. Although both antibodies labelled subsets of macrophages, the antibodies also reacted with granulocytes and dendritic cells. The antigens recognized by these antibodies were identified by metabolic and cell surface labelling followed by immunoprecipitation and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). MRC OX-41 recognized a surface protein of 110,000-120,000 MW, while MRC OX-42 immunoprecipitated three polypeptides with molecular weights of 160,000, 103,000 and 95,000. The Fab fragment of MRC OX-42 antibody inhibited complement-mediated rosette formation between sensitized erythrocytes and rat macrophages and granulocytes. Membrane molecules with similar biochemical and functional properties to MRC OX-42 antigen have been identified in mouse and man as the receptors for iC3b, and it is probable that MRC OX-42 antibody recognizes the rat homologue of the receptors in these other species.

Long-Term Immunogenicity and Efficacy of Hepatitis B Vaccine in Homosexual Men

Abstract: To study the duration of antibody persistence and protection provided by the hepatitis B vaccine, we followed 773 homosexual men for five years after completion of vaccination. Among the 635 participants in whom antibody levels above 9.9 sample ratio units (SRU) developed after vaccination, 15 percent lost antibody altogether, and in another 27 percent, antibody levels declined below 10 SRU within five years. The extent of the maximal antibody response strongly predicted the persistence of protective antibody. Hepatitis B infection occurred in 55 men; 8 of these infections were clinically important (characterized by the presence of the hepatitis B surface antigen and elevation of liver-enzyme levels), and two of the patients became hepatitis B virus carriers. The long-term risk of hepatitis B infection was inversely related to the maximal antibody response to vaccine. Most severe infections occurred among those who responded poorly or had no response to the vaccination. The risk of late infection with hepatitis B in those with an initially adequate vaccine response increased markedly when antibody levels decreased below 10 SRU, but only 1 of 34 late infections resulted in viremia and liver inflammation. A second series of vaccinations induced a moderate antibody response in 50 percent of the subjects who initially had no response or a poor response; however, the persistence of antibody was poor. Both antibody loss and the risk of severe disease should be considered when booster-dose strategies for the hepatitis B vaccine are being designed.

A neuronal antigen in the brains of Alzheimer patients.

Abstract: A monoclonal antibody was prepared against pooled homogenates of brain tissue from patients with Alzheimer's disease. This antibody recognizes an antigen present in much higher concentration in certain brain regions of Alzheimer patients than in normal brain. The antigen appears to be a protein present in neurons involved in the formation of neuritic plaques and neurofibrillary tangles, and in some morphologically normal neurons in sections from Alzheimer brains. Partial purification and Western blot analysis revealed the antigen from Alzheimer brain to be a single protein with a molecular weight of 68,000. Application of the same purification procedure to normal brain tissue results in the detection of small amounts of a protein of lower molecular weight.

Functional role for the 170- to 180-kDa glycoprotein specific to drug-resistant tumor cells as revealed by monoclonal antibodies.

Abstract: An overexpression of the plasma membrane glycoprotein of relative molecular size 170-180 kDa is consistently found in different multidrug-resistant human and animal cell lines, although the functional role of the protein in multidrug resistance is not known. Two monoclonal antibodies that interfere with biochemical functions were generated against the human myelogenous leukemia K-562 cells resistant to adriamycin (K-562/ADM). These antibodies, designated MRK16 and MRK17, are specifically reactive to K-562/ADM and a human ovarian cancer cell line resistant to adriamycin (2780AD). MRK16 modulated vincristine and actinomycin D transport in the resistant cells, while MRK17 specifically inhibited the growth of the resistant cells. Both antibodies recognized the 170- to 180-kDa glycoprotein. These data indicate that the 170- to 180-kDa glycoprotein is involved, directly or indirectly, in the drug transport mechanisms and the proliferation of multidrug-resistant tumor cell lines.

The Receptor with High Affinity for Immunoglobulin E

Abstract: This review is about one of the physiologically important macromolecules that interact with the Fc domains of immunoglobulins. Such substances (complement, "immunoglobulin binding factors," Fc receptors) can convert the simp le binding of antigen to antibody into a biologically meaningful event. The protein we review he re-the Fc receptor with high affinity for monomeric immunoglobulin E (IgE}-is only one of several proteins that interact with IgE (1-5). In addition to high affinity, its special characteristic is its distribution on the plasma membrane of mast cells and basophils exclusively. Activation of this receptor initiates release of preformed mediators contained in int racellular granules and the biosynthesis of a variety of biologically active lipids such as the leukotrienes. Here we review what is known about the structure of this receptor and the early biochemical events that it initiates. We do not consider the conse quences of

Functional subsets of human helper-inducer cells defined by a new monoclonal antibody, UCHL1.

Abstract: The monoclonal antibody UCHL1 identified an antigen present on most thymocytes, a subpopulation of resting T cells within both the CD4 and CD8 subsets, and on mature activated T cells. The UCHL1 determinant is also present on cells of the myeloid lineage, but not normal B cells or NK cells. Functionally, UCHL1 identifies a subpopulation of T cells which proliferates maximally to soluble antigen and provides maximum help for PWM-stimulated immunoglobulin synthesis. In contrast, the UCHL1- cells do not induce immunoglobulin synthesis and do not proliferate in the presence of soluble antigen, although both the UCHL1- and the UCHL1+ fractions of T cells proliferate well in the presence of PHA. By standard immunoprecipitation techniques and SDS page, the antigen recognized by UCHL1 was found to have a molecular weight of 180,000-185,000. Preclearing experiments using antibodies identifying the leucocyte common antigen, LCA, and the lymphocyte function-associated antigen, LFA-1, which have similar molecular weights to UCHL1, showed that the UCHL1 determinant is not biochemically related to these antigens.

Long-term cultures of HTLV-III--infected T cells: a model of cytopathology of T-cell depletion in AIDS.

Abstract: Long-term cultures were established of HTLV-III-infected T4 cells from patients with the acquired immune deficiency syndrome (AIDS) and of T4 cells from normal donors after infection of the cells in vitro. By initially reducing the number of cells per milliliter of culture medium it was possible to grow the infected cells for 50 to 60 days. As with uninfected T cells, immunologic activation of the HTLV-III-infected cells with phytohemagglutinin led to patterns of gene expression typical of T-cell differentiation, such as production of interleukin-2 and expression of interleukin-2 receptors, but in the infected cells immunologic activation also led to expression of HTLV-III, which was followed by cell death. The results revealed a cytopathogenic mechanism that may account for T4 cell depletion in AIDS patients and suggest how repeated antigenic stimulation by infectious agents, such as malaria in Africa, or by allogeneic blood or semen, may be important determinants of the latency period in AIDS.

Isolation of human-p53-specific monoclonal antibodies and their use in the studies of human p53 expression

Abstract: The isolation and construction of a complete human p53 cDNA and subsequent expression in monkey cells is described. A set of new anti-(human p53) monoclonal antibodies has also been obtained and used to show the expression of the human p53 cDNA in cos-l cells. These antibodies enable the specific detection of human p53, which is synthesised in the presence of p53 from other species. Fusion proteins of p53 with beta-galactosidase were used firstly as antigen and secondly, in conjunction with competition assays, to localise the determinants recognized by the antibodies. At least two previously unrecognized epitopes are involved and two of the antibodies are human-p53-specific. The epitopes are denaturation-resistant and the antibodies are, therefore, valuable for immunoblotting as well as immunoprecipitation and enzyme-linked immunoassay. Transfection of plasmids containing complete human p53 cDNA into monkey (cos-l) cells cause expression of human p53 recognized by the monoclonal antibodies. Control plasmids did not induce immunoreactive protein.

Antigen-driven selection of virgin and memory B cells.

Abstract: This review has summarized the evidence indicating that far more B cells are produced in adult bone marrow than are required to maintain B cell numbers in the periphery. It is shown that most if not all these newly-formed B cells have the potential to become mature peripheral B cells. However, to do this they need to receive an appropriate signal in secondary lymphoid organs. Cells failing to receive such a signal die after a brief period. Two separate situations have been identified which result in recruitment of newly-formed virgin B cells into the peripheral B-cell pool: Following activation by antigen. When the peripheral B-cell pool has been depleted. It is proposed that the first of these signals requires T help and is initiated by antigen presented on interdigitating cells in extrafollicular areas of secondary lymphoid organs. This process seems to be confined to periods immediately following administration of antigen and does not continue in established immune responses to thymus-dependent antigens. It seems probable that continued B cell activation, occurring during long term antibody responses, takes place in the follicles of secondary lymphoid organs and is driven by antigen presented on follicular dendritic cells. Indirect evidence is cited which suggests that somatic mutation in rearranged immunoglobulin V-region genes occurs mainly following B-cell activation in follicles and not during primary B lymphopoiesis. It is suggested that this may involve a hypermutation process which is switched on in activated B cells in germinal centers. Evidence is presented suggesting that plasma cells generated from B cells activated early in immune responses have an average life-span of less than 3 d. However, plasma cells generated in established responses appear to have an average life-span in excess of 20 d. Later sections in the review consider how B-cell recruitment in thymus-independent antibody responses differs markedly from recruitment during thymus-dependent responses. The possible role of splenic marginal zone B cells in some thymus-independent antibody responses is discussed and the evidence indicating that SIgM + ve, IgD-ve marginal zone B cells develop as a distinct population from recirculating SIgM + ve, IgD + ve B cells is summarized.

Distribution of Oncofetal Antigen Tumor-associated Glycoprotein-72 Defined by Monoclonal Antibody B72.3

Abstract: Murine monoclonal antibody B72.3, prepared against a membrane-enriched extract of human metastatic carcinoma, was reacted with a spectrum of adult and fetal human tissues using avidin-biotin-complex immunohistochemical techniques to evaluate the expression of the reactive tumor associated glycoprotein (TAG)-72 antigen. TAG-72 was shown to be expressed in several epithelial-derived cancers including 94% of colonic adenocarcinomas, 84% of invasive ductal carcinomas of the breast, 96% of non-small cell lung carcinomas, 100% of common epithelial ovarian carcinomas, as well as the majority of pancreatic, gastric, and esophageal cancers evaluated. TAG-72 expression was not observed, however, in tumors of neural, hematopoietic, or sarcomatous derivation, suggesting that the TAG-72 antigen is "pancarcinoma" in nature. Appreciable monoclonal antibody B72.3 reactivity was generally not observed in adult normal tissues, with limited reactivity noted in a few benign lesions of the breast and colon. TAG-72 antigen expression was detected, however, in fetal colon, stomach, and esophagus, thus defining TAG-72 as an oncofetal antigen. TAG-72 has previously been shown to be distinct from carcinoembryonic antigen and other tumor associated antigens. The pancarcinoma distribution and lack of significant reactivity with normal adult tissues of monoclonal antibody B72.3 suggest its potential diagnostic and therapeutic utility for human carcinomas.

Human immunodeficiency viruses.

Abstract: The human immunodeficiency virus (HIV) is the etiologic agent of AIDS. HIVs are enveloped plus-stranded RNA viruses. The HIV genome is organized similarly to other retroviruses. It contains the gag, pol, and env genes which encode structural proteins, viral enzymes, and envelope glycoproteins, respectively. The major structural proteins which are encoded by the gag gene include p17, p24, p7, and p9. Replication begins with the attachment of virus to the target cell via the interaction of gp120 and the cellular receptor CD4. Both HIV-1 and HIV-2 have the same modes of transmission. The most common mode of HIV infection is sexual transmission at the genital mucosa through direct contact with infected blood fluids, including blood, semen, and vaginal secretions. Serological testing for HIV antibody is used for various purposes, including primary diagnosis, screening of blood products, management of untested persons in labor and delivery, evaluation of occupational exposures to blood/body fluid, and epidemiological surveillance. The first generation of HIV antibody assays relied on the detection of antibody to HIV viral protein lysates. A test using a sandwich-capture format and significantly more blood than other methods was more sensitive in early seroconversion. HIV-1 RNA load testing is sometimes requested to resolve equivocal serologic findings or to facilitate the diagnosis of HIV-1 infection during the acute phase or in a pediatric setting.

A lymphoid cell surface glycoprotein involved in endothelial cell recognition and lymphocyte homing in man.

Abstract: We describe a 90-kDa lymphocyte surface glycoprotein, recognized by the monoclonal antibody Hermes-1, that is involved in endothelial cell recognition and lymphocyte trafficking in man. This molecule (a) is selectively expressed on normal or transformed lymphoid cells that are able to recognize and bind to high endothelial venules (HEV, specialized vessels that mediate lymphocyte exit from the blood into lymphoid organs); (b) appears to be linked to HEV recognition function since, in fluorescence- activated cell sorting of variants of a cloned cell line, HEV binding ability co-selects with the Hermes-1 antigen; (c) bears the predominant cell surface epitopes recognized by heterologous anti-human lymphocyte antibodies able to interfere with lymphocyte binding to HEV; and (d) is structurally similar to a previously described mouse lymphocyte surface receptor for HEV. These findings demonstrate that the molecule defined by Hermes-1 either functions as a specific lymphocyte surface receptor for HEV, or is both precisely coregulated and physically and/or functionally associated with such receptors. The expression of this putative receptor for HEV on normal human lymphocyte populations parallels, and thus presumably helps determine, their migratory status in vivo. Hermes-1 should be a powerful tool for analyzing the role of endothelial cell recognition in the traffic of normal and neoplastic human lymphocytes.

Serum and nasal wash antibodies associated with resistance to experimental challenge with influenza A wild-type virus.

Abstract: To identify immunological predictors of resistance to influenza A infection and illness, the immunological status of live and inactivated virus vaccines subsequently challenged with H1N1 or H3N2 wild-type virus was examined. We refer to prechallenge antibodies of vaccinees receiving live attenuated virus as infection induced and those receiving inactivated virus as inactivated vaccine induced. Inactivated vaccine-induced protection against wild-type virus infection or illness correlated with the level of neuraminidase-inhibiting antibody in serum, local hemagglutinin immunoglobulin G (IgG) (but not IgA) enzyme-linked immunosorbent assay antibody, and hemagglutination-inhibiting antibody in serum. In contrast, infection-induced resistance to wild-type virus infection correlated with local hemagglutinin IgA antibody and neuraminidase-inhibiting antibody in serum, but not with hemagglutination-inhibiting antibody in serum. These observations suggest that live vaccine virus infection-induced and inactivated vaccine-induced immunity may involve different compartments of the immune system; sufficient antibody in either serum or nasal secretions is capable of conferring resistance.

Regulation of the assembly and expression of variable-region genes.

Abstract: During the past several years, it has become increasingly evident that the regulation of immunoglobulin (Ig) gene assembly and expression is intrinsically related to the progression of B-cell precursors to the B-cell differentiation stage. The general focus of this review is to describe in detail the mechanism of Ig variable-region gene assembly and to explore the possible regulatory mechanisms that the cell exploits to control these genomic rearrangement events. Because assembly of the variable region of the T-cell antigen-receptor genes appears to be mediated by the same molecular elements, the general principles we describe should apply to both Ig and T cell-receptor variable-region genes. The immune system is capable of responding to an almost infinite number of antigenic challenges by producing a tremendous diversity of antibody specificities. Each antibody molecule consists of heavy (H) and light (L) immunoglobulin polypeptide chains. The carboxy terminus of H and L chains is a region of constant amino acid sequence. The constant region of the H chain is involved in a variety of effector functions, such as Fe-receptor binding and complement fixation. The amino terminus of both these chains contains a region of variable amino acid sequences (designated the variable region) that are usually unique to the chains in a given antibody molecule; the variable regions of a single H and L chain interact to form an antigen-binding pocket. It is now clear that the DNA sequences encoding

Immunohistochemical analysis of the cellular infiltrate in multiple sclerosis lesions

Abstract: Immunohistochemical staining of 16 brains post mortem from patients with progressive multiple sclerosis and of two biopsy specimens from patients with acute demyelinating disease was performed using a panel of monoclonal antibodies reactive with T cells and T-cell subsets, B cells, and Ia (HLA-DR) antigens. Lymphocytic perivascular cuffs were most prominent at the edge of active plaques and were occasionally seen in areas with no evidence of demyelination or macrophage infiltration. Perivascular cuffs consisted predominantly of T cells and Ia+ cells, with many T8+ cells and variable numbers of T4+ cells. T8/T4 ratios in cuffs varied between 1:1 and 50:1. In normal-appearing white matter, cuffs were sparse and were predominantly T8+. The distribution of T cells in the parenchyma resembled that seen in perivascular cuffs, namely, predominantly T8+ cells and variable numbers of T4+ cells. Many Ia+ cells were present in active lesions, and the majority of these cells appeared, by histological criteria, to be macrophages. Tissue macrophages were also stained lightly by the anti-T4 antibody. No brain had more T4+ than T8+ cells, determined using both T4 and Leu3a monoclonal antibodies. B1+ cells were rare. These results suggest that the cellular infiltrate in multiple sclerosis consists predominantly of T cells and macrophages and that there is an overrepresentation of T8+ cells compared with T4+ cells.

Epitopes of the CD4 antigen and HIV infection.

Abstract: The CD4 (or T4) surface antigen of human T lymphocytes is an important part of the receptor for the human immunodeficiency virus (HIV) After binding to the receptor, the HIV may enter the T cell and induce the formation of syncytia In an attempt to identify the receptor site more closely, monoclonal antibodies (Mab's) to CD4 were tested for their ability to block HIV infection in a syncytium formation assay, and the CD4 epitopes so identified were mapped by antibody cross-blocking The antibodies that showed strong inhibition of HIV fell into two main families while a third group of Mab's blocked syncytia formation weakly or not at all Several different isolates of HIV as well as the laboratory strain CBL1 grown in CEM cells were used to induce the syncytia The data indicate that only some epitopes of CD4 are important for virus binding and imply that the virus-binding site for CD4 is conserved in different isolates of HIV with substantially divergent env gene sequences Preliminary studies of patients suggest that polymorphism of these epitopes does not play a role in determining susceptibility to infection

Characterization of the antibody response in mice with type II collagen-induced arthritis, using monoclonal anti-type II collagen antibodies.

Abstract: Twenty monoclonal antibodies reactive with type II collagen were characterized as to their determinant specificity and their reactivity with cartilage-derived components. The monoclonal antibodies reacted with 7 different epitopes on the native type II collagen triple helical structure. Antibodies defining 3 of these epitopes occurred more frequently in sera from arthritic mice than in sera from nonarthritic mice. In vivo injection of some selected autoreactive antibodies caused synovitis, but in no case did it give rise to full-blown arthritis.

Monoclonal antibody G 250 recognizes a determinant present in renal-cell carcinoma and absent from normal kidney.

Abstract: This report describes a monoclonal antibody designated G 250, subclass IgGl, that recognizes an antigen preferentially expressed on cell membranes of renal-cell carcinoma cells (RCC) and not expressed in normal proximal tubular epithelium. G 250 antibody reacted with 46 of 47 primary RCC, with 7 of 8 RCC metastases and with a few other malignant tumors. The staining pattern of G 250 differs from that of other RCC-related antibodies described. Preliminary experiments show that this antibody can be used to visualize RCC xenografts in nude mice by immunoscintigraphy.

Defective regulation of Epstein-Barr virus infection in patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related disorders.

Abstract: Patients with the acquired immunodeficiency syndrome (AIDS) acquire undifferentiated B-cell lymphomas that are similar to African Burkitt's lymphoma and contain Epstein-Barr virus (EBV). Using an in vitro assay system that measures a complex of cellular responses to EBV-infected lymphocytes, we found that B cells from 7 patients with AIDS and from 10 patients with AIDS-related disorders produced abnormally low numbers of immunoglobulin-secreting cells (P less than 0.001 as compared with normal controls) and that T-cell suppression, which was greater than 80 percent in EBV-seropositive normal controls, was absent. Instead, the patients' T cells markedly increased immunoglobulin production induced by EBV. In further studies, we determined that the mean frequency of circulating EBV-infected B cells capable of spontaneous outgrowth in vitro was 13 per 10(6) B cells in 7 patients with AIDS and 21 per 10(6) B cells in 10 patients with AIDS-related disorders--figures that were significantly higher than the mean in normal controls (P less than 0.001). Thus, patients with AIDS or AIDS-related disorders may be predisposed to the development of EBV-containing lymphomas, because they have a profound defect of T-cell immunity to EBV and abnormally high numbers of EBV-infected B cells in the circulation.

The Nucleocapsid of Hepatitis B Virus Is Both a T-Cell-Independent and a T-Cell-Dependent Antigen

Abstract: One characteristic of the immune response during hepatitis B virus (HBV) infection in humans is the vigorous production and subsequent persistence of antibodies of immunoglobulin (Ig) classes M and G to the nucleocapsid antigen (HBcAg). In this study HBcAg was shown to be similarly immunogenic in mice. When injected into athymic (nude) B10.BR and athymic BALB/c mice, HBcAg induced IgM and IgG class antibodies to HBc in spite of the absence of T cells in nude mice. In euthymic mice, HBcAg efficiently stimulated T-cell proliferation in vitro and helper T-cell function in vivo. The dual functions of HBcAg as a T-cell-independent and a T-cell-dependent antigen may explain its enhanced immunogenicity. Denaturation of HBcAg yields a nonparticulate antigen designated HBeAg; when HBeAg was used as the immunogen, antibody production required helper T-cell function. Although HBcAg and HBeAg are serologically distinct, they are structurally related, and in these experiments were highly cross-reactive at the T-cell level. These results suggest that the elevated levels of IgM antibodies to HBc and the enhanced immunogenicity of HBcAg during HBV infection in humans reflect the ability of HBcAg to directly activate B cells to produce antibodies to HBc in the presence or absence of HBcAg- or HBeAg-sensitized T cells.

HTLV-III/LAV-neutralizing antibodies to an E. coli-produced fragment of the virus envelope

Abstract: Immunization with either an Escherichia coli recombinant segment of the human T-cell lymphotropic virus (HTLV-III/LAV) envelope protein (gp 120) or with deglycosylated gp 120 envelope protein produced antibodies that neutralize HTLV-III/LAV infection in vitro. Virus neutralization titers of these antisera were equivalent to those obtained with purified native gp120 as immunogen. This localizes at least one class of neutralizing epitopes to the carboxyl-terminal half of the molecule. In addition, native gp120 prevented HTLV-III/LAV--mediated cell fusion, whereas the recombinant gp120 fragment did not. This shows that although glycosylation is not required for induction of neutralizing antibodies, it may be important for interaction with CD4, the virus receptor. A segment of the HTLV-III/LAV envelope produced in E. coli may be an important ingredient of a vaccine for acquired immune deficiency syndrome.

Human monocytes and U937 cells bear two distinct Fc receptors for IgG.

Abstract: Several convergent lines of evidence have led us to propose that human monocytes and the related cell line U937 possess a second class of IgG Fc receptor (FcR) in addition to the 72-Kd high affinity FcR previously described. IgG affinity purification from detergent lysates of surface radiolabeled U937 cells has yielded both a 40-Kd IgG-binding membrane protein (p40) and the 72-Kd FcR protein. By the same procedure, only the p40 was isolated from the erythroblast cell line K562 and from the B cell lines, Daudi and Raji. Serologic cross-reactivity between the 40-Kd FcR on U937 and Daudi cells was demonstrated using a goat anti-FcR antiserum. A murine (m) monoclonal antibody, raised against the FcR of K562 cells, precipitated the 40-Kd FcR from lysates of U937 and K562 cells but not from Daudi or Raji cells. This antibody, referred to as anti-p40 (IV.3), selectively inhibited the binding of murine IgG1-coated erythrocytes to U937 cells, whereas monomeric human IgG selectively inhibited binding of human anti-Rh(D)-coated erythrocytes to U937 cells. Both Daudi and U937 cells mediated mIgG1 anti-T3 (Leu-4)-induced stimulation of T lymphocytes. In contrast, mIgG2a anti-T3 (OKT3)-induced stimulation was supported effectively by U937 cells but only modestly by Daudi cells. Intact IgG or Fab fragments of anti-p40 (IV.3) blocked mIgG1 anti-T3 (Leu-4) stimulation but not mIgG2a anti-T3 (OKT3) stimulation of T cells; monomeric human IgG blocked only OKT3-induced stimulation. The simplest interpretation of these results is that human monocytes and U937 cells bear two classes of IgG FcR, one of 72 Kd and the other, as described above, of 40 Kd. We propose that the 72-Kd FcR mediates rosette formation with red cells coated by human anti-Rh IgG as well as T cell stimulation by mIgG2a anti-T3 (OKT3) and that the 40-Kd FcR mediates rosette formation with erythrocytes bearing mIgG1 as well as T cell stimulation by mIgG1 anti-T3 (Leu-4). Furthermore, we suggest that these two FcR are the human homologues of the murine macrophage FcRI (binding mIgG2a) and FcRII (binding mIgG2b/1).