Showing papers on "Antibody published in 1987"

Single polypeptide chain binding molecules

Abstract: The invention pertains to a single polypeptide chain binding molecule which has binding specificity and affinity substantially similar to the binding specificity and affinity of the light and heavy chain aggregate variable region of an antibody, to genetic sequences coding therefor, and to recombinant DNA methods of producing such molecule and uses for such molecule.

Interferon-gamma and B cell stimulatory factor-1 reciprocally regulate Ig isotype production

Abstract: Gamma interferon (IFN-gamma) and B cell stimulatory factor-1 (BSF-1), also known as interleukin-4, are T cell-derived lymphokines that have potent effects on B cell proliferation and differentiation. They are often secreted by distinct T cell clones. It is now shown that IFN-gamma stimulates the expression of immunoglobulin (Ig) of the IgG2a isotype and inhibits the production of IgG3, IgG1, IgG2b, and IgE. By contrast, BSF-1 has powerful effects in promoting switching to the expression of IgG1 and IgE but markedly inhibits IgM, IgG3, IgG2a, and IgG2b. These results indicate that BSF-1 and IFN-gamma as well as the T cells that produce them may act as reciprocal regulatory agents in the determination of Ig isotype responses. The effects of IFN-gamma and BSF-1 on isotype expression are independent.

Recombinant antibodies and methods for their production

Abstract: An altered antibody is produced by replacing the complementarity determining regions (CDRs) of a variable region of an immunoglobulin (Ig) with the CDRs from an Ig of different specificity, using recombinant DNA techniques. The gene coding sequences for producing the altered antibody may be produced by site-directed mutagenesis using long oligonucleotides.

Identification of a monoclonal antibody specific for a murine T3 polypeptide

Abstract: A monoclonal antibody (145-2C11) specific for the murine T3 complex was derived by immunizing Armenian hamsters with a murine cytolytic T-cell clone. The antibody is specific for a 25-kDa protein component (T3-epsilon) of the antigen-specific T-cell receptor. It reacts with all mature T cells and can both activate and inhibit T-cell function. These results identify T3-epsilon as a cell surface protein involved in the transduction of activation signals.

Molecular cloning of the CD2 antigen, the T-cell erythrocyte receptor, by a rapid immunoselection procedure.

Abstract: A cDNA encoding the CD2 antigen has been isolated by a highly efficient technique based on transient expression in COS cells and adherence of cells expressing surface antigen to antibody-coated dishes. COS cells expressing a CD2 cDNA isolated by this method readily formed rosettes with sheep as well as human and other mammalian erythrocytes. Pretreatment of transfected COS cells with anti-CD2 antibody, or pretreatment of human erythrocytes with anti-LFA-3 antibody, abolished rosette formation.

Immunoglobulin A (IgA): molecular and cellular interactions involved in IgA biosynthesis and immune response.

Abstract: Publisher Summary This chapter discusses the impact of new information concerning IgA physiology on the immune system. IgA should not be considered only as an isotype providing specific humoral protection of mucosal surfaces but as an integral component of the entire immune system. An unusual structural feature of human IgA is the heterogeneity of the molecular forms with characteristic distribution in various body fluids. Though most IgA in serum displays a typical four-polypeptide chain structure of the basic molecule with two Q and two light (L) chains, external secretions contain dimeric and tetrameric, disulfide-linked molecules associated with additional polypeptides-J (joining) chain and secretory component (SC). IgA-producing plasma cells are distributed in various lymphoid and nonlymphoid tissues and are particularly preponderant in the lamina propria of the gut; in salivary, lacrimal, and lactating mammary glands; and in the human bone marrow. IgA occurs in different body fluids in predominantly polymeric or monomeric (plasma, cerebrospinal fluid) forms with a characteristic distribution of IgAl and IgAz molecules. Under normal conditions, an absolute majority of IgA-containing cells in secretory glands and tissues also contain J chain whereas such cells in, for example, normal bone marrow does not. Staining with fluorochrome-labeled anti-J chain is enhanced by the pretreatment of alcohol-fixed tissue sections with acid urea, which leads to the exposure of masked antigenic determinants of intracellular J chain. Specialized lymphoid tissues associated with mucosal surfaces play an essential role in the induction and regulation of generalized immune responses in external secretions.

The common mucosal immune system and current strategies for induction of immune responses in external secretions

Abstract: The selective induction of antibodies in external secretions is desirable for the prevention of various systemic as well as predominantly mucosa-restricted infections. An enormous surface area of mucosal membranes is protected primarily by antibodies that belong, in many species, to the IgA isotype. Such antibodies are produced locally by large numbers of IgA-containing plasma cells distributed in subepithelial spaces of mucosal membranes and in the stroma of secretory glands. In humans and in some animal species, plasma-derived IgA antibodies do not enter external secretions in significant quantities and systemically administered preformed IgA antibodies would be of little use for passive immunization. Systemic administration of microbial antigens may boost an effective S-IgA immune response only in a situation whereby an immunized individual had previously encountered the same antigen by the mucosal route. Local injection of antigen in the vicinity of secretory glands is usually accompanied by an undesirable concomitant systemic response and frequently requires the addition of adjuvants that are unacceptable for administration in humans. Immunization routes that involve ingestion or possibly inhalation of antigens lead to the induction of not only local but also generalized immune responses manifested by the parallel appearance of S-Iga antibodies to ingested or inhaled antigens in secretions of glands distant from the site of immunization. Based on extensive studies in animal models as well as in humans, convincing evidence is available that antigen-sensitized and IgA-committed precursors of plasma cells from GALT are disseminated to the gut, other mucosa-associated tissues, and exocrine glands. However, due to the limited absorption of desired antigens from the gut lumen of orally immunized individuals, repeated large doses of antigens are required for an effective S-IgA response. Novel antigen delivery systems for the stimulation of such responses are currently being examined in several laboratories. Live attenuated or genetically manipulated bacteria expressing other microbial antigens have also been used for selective colonization of gut-associated lymphoid tissues. Unique antigen packaging and the use of adjuvants suitable for oral administration hold promise for an efficient antigen delivery to critical tissues in the intestine and deserve extensive exploration. The oral immunization route appears to have many advantages over systemic immunization.(ABSTRACT TRUNCATED AT 400 WORDS)

Veterinary Immunology: An Introduction

Abstract: General features of the immune responses antigens and antigenicity destruction of foreign material - the myeloid system mactophages and antigen processing the major histocompatibility complex the tissues of the immune system lymphocytes the helper T cell response lymphokines and cytokines antibodies the genetic basis of antigen recognition the cellular basis of antibody formation the complement system effector T cell function tissue transplantation resistance to tumours tolerance and regulation of the immune system serology - the detection and measurement of antibodies immunity at body surfaces immunity in the fetus and newborn general principles of vaccination and vaccines resistance to bacteria and related organisms resistance to viruses immunity to parasites inflammation type 1 hypersensitivity erythrocyte antigens adn type 2 hypersensitivity type 3 hypersensitivity cell-mediated (type 4) hypersensitivity autoimmunity - general principles organ-specific autoimmune diseases the systemic immunological diseases primary immune deficiencies secondary immunological defects drugs that affect the immune system the phylogeny of the immune system.

Comparison of the effector functions of human immunoglobulins using a matched set of chimeric antibodies.

Abstract: Cell lines have been established that secrete a matched set of human chimeric IgM, IgG1, IgG2, IgG3, IgG4, IgE, and IgA2 antibodies that are directed against the hapten 4-hydroxy-3-nitrophenacetyl. These chimeric antibodies secreted from mouse plasmacytoma cells behave exactly like their authentic human counterparts in SDS-PAGE analysis, binding to protein A and in a wide range of serological assays. The antibodies have been compared in their ability to bind human C1q as well as in their efficacy in mediating lysis of human erythrocytes in the presence of human complement. A major conclusion to emerge is that whereas IgG3 bound C1q better than did IgG1, the chimeric IgG1 was much more effective than all the other IgG subclasses in complement-dependent hemolysis. The IgG1 antibody was also the most effective in mediating antibody-dependent cell-mediated cytotoxicity using both human effector and human target cells. These results suggest that IgG1 might be the favoured IgG subclass for therapeutic applications.

Parathyroid hormone-related protein purified from a human lung cancer cell line

Abstract: A protein with biological activities similar to parathyroid hormone (PTH) has been purified from serum-free culture medium obtained from a human lung cancer cell line (BEN). A major protein band of 18 kDa was obtained on NaDodSO4/polyacrylamide gels, with faint bands at 35 kDa and 67 kDa. Biological activity was associated only with the 18-kDa band. Amino acid sequence analysis of the material purified by HPLC revealed that 8 of the 16 residues were identical with those of human PTH. Antibody raised to a corresponding synthetic peptide recognized the PTH-related material but showed less than 1% cross-reactivity with human PTH amino-terminal peptides. BEN cells contained PTH DNA, but not PTH messenger RNA, indicating involvement of another gene. The purified PTH-related protein had a specific biological activity approximately equal to 6 times greater than that of bovine PTH(1-34). The PTH-related protein may have a role in the syndrome of humoral hypercalcemia of malignancy.

γ Interferon, CD8 + T cells and antibodies required for immunity to malaria sporozoites

Abstract: This study was designed to test the hypothesis that T-cell effector mechanisms are required for protective immunity to malaria sporozoites. Administration of neutralizing monoclonal antibodies against gamma interferon (gamma IFN) to immune hosts, reversed sterile immunity to sporozoite challenge, by allowing the growth of exoerythrocytic forms (EEF) and thus the development of parasitaemia. Immune animals also developed infections when depleted in vivo of their suppressor/cytotoxic T cells expressing the CD8 antigen (CD8+) but not when depleted of helper T cells expressing CD4 antigen (CD4+), before sporozoite challenge. Passive transfer of immune immunoglobin alone, or adoptive transfer of immune T cells alone, conferred partial protection to naive recipients. Transfer of both immune components resulted in significantly greater protection. This transferred immunity was reversed by the in vivo neutralization of gamma IFN. Thus, sterile immunity to sporozoite challenge requires the neutralization of sporozoites by antibodies and the inhibition of EEF development by gamma IFN with the participation of CD8+ cells.

The role of clonal selection and somatic mutation in autoimmunity.

Abstract: Polyclonal activation has been proposed as the reason that autoantibodies are produced during autoimmune disease. This model denies a role for specific antigen selection of B cells and predicts instead a multiclonal population of unmutated or randomly mutated autoantibodies. We have found that the genetic features and clonal composition of spontaneously derived immunoglobulin G (IgG) antiself-IgG (rheumatoid factor (RF] autoantibodies derived from the autoimmune MRL/lpr mouse strain are inconsistent with both the predictions of this model and the actual outcome of experimental polyclonal activation. Instead we have found that MRL/lpr RFs are oligoclonal or even monoclonal in origin. They harbour numerous somatic mutations which are distributed in a way that suggests immunoglobulin-receptor-dependent selection of these mutations. In this sense, the MRL/lpr RFs resemble antibodies elicited by exogenous antigens after secondary immunization. The parallels suggest that, like secondary immune responses, antigen stimulation is important in the generation of MRL/lpr RFs.

Multiepitopic immunometric assay

Abstract: The invention relates to an immunometric assay for a multivalent antigen in a sample which comprises forming a complex of the antigen together with multiple immobilized monoclonal antibodies against different epitopes of the antigen and with a detectably labeled soluble monoclonal antibody which is identical to one of the multiple immobilized antibodies The labeled antibody associated with the complex is separated from the remaining soluble antibody and the detectably labeled antibody associated with the complex or unassociated with the complex is detected Any one of the multiple immobilized monoclonal antibodies shows, by itself, substantially less binding towards the antigen in the immunometric assay, when used with itself or another monocolonal antibody in soluble labeled form, than when used with the multiple immobilized antibodies in combination

Immunochemical methods in cell and molecular biology

Abstract: This book presents immuno-chemical techniques for isolating and analysing a wide variety of biological products. CONTENTS: Introduction, Polyclonal Antiserum Production;Polyclonal Antiserum Processing;Uses of Polyclonal Antisera. Production and Use of Monoclonal Antibodies;Synthetic Petpides: A New Development in Protein Immunochemistry;and Technical Supplement.

Anticardiolipin antibodies: isotype distribution and phospholipid specificity.

Abstract: Quantitative isotype specific enzyme linked immunosorbent assay (ELISA) was used to determine the distribution of immunoglobulin isotypes and phospholipid specificities of anticardiolipin (anti-CL) antibodies in 40 patients with one or more of the following 'antiphospholipid (anti-PL) antibody associated clinical complications'--namely, thrombosis, fetal loss, thrombocytopenia. Twelve of 40 patients had IgG, IgM, and IgA anti-CL antibodies. Ten patients had IgG and IgM, five patients had IgG and IgA, and three patients had IgM and IgA anti-CL antibodies. There was no statistical association between any single isotype or any group of isotypes with thrombosis, fetal loss, or thrombocytopenia. The presence of IgG anti-CL antibodies in 36 of the 40 patients suggests that this isotype may be most important in determining clinical complications, but there were four patients without IgG anti-CL antibodies who also appeared susceptible to thrombosis, fetal loss, and thrombocytopenia. IgG, IgM, and IgA anti-CL antibodies bound the negatively charged phospholipids, phosphatidylserine and phosphatidylinositol, but not the zwitterionic phospholipid, phosphatidylcholine. There was no significant difference between binding to cardiolipin and binding to other negatively charged phospholipids, suggesting that the specificity of these antibodies is for negatively charged phospholipids in general rather than for cardiolipin in particular.

Chronic progressive myelopathy associated with elevated antibodies to human T-lymphotropic virus type I and adult T-cell leukemialike cells

Abstract: Six adult patients had a chronic progressive myelopathy that possessed the following features: (1) high antibody titers to human T-lymphotropic virus type I (HTLV-I) in serum and cerebrospinal fluid (CSF); (2) predominantly upper motor neuron disorder, symmetrical, with mild sensory and bladder disturbances; and (3) presence of adult T-cell leukemia–like cells in both peripheral blood and CSF. We refer to this entity as HTLV-I–associated myelopathy (HAM). Electrophoretic studies of immunoglobulin G in CSF using Western blot analysis characteristically demonstrated p24 and p32 bands. Rates of intra-blood–brain barrier synthesis were determined and found increased in the patients with HAM. Corticosteroid treatment produced clinical improvement in all of 4 patients. A retrospective survey of CSF samples was carried out in 287 patients with neurological disorders, and 6 additional patients with HAM were identified.

Mutation drift and repertoire shift in the maturation of the immune response.

Abstract: The halltnark of the immune response is its specificity and the specificity is directly correlated with the affinity of the antigen-antibody interaction. The requirement for high affinity antibodies may be more important than specificity alone, since antibodies are designed to detect soluble antigens which are sometimes capable of inflicting great harm at very low concentrations (e.g. toxins). This may not be required by. or may even be a disadvantage to T-cell responses where the affinity for the ligand involves interactions of the T-cell receptor not only with antigen, but also with other molecules, e.g. those involved in MHC restriction (Yague et al. 1985. Dembic et al. 1986). T cells therefore may not have developed the equivalent of the elaborate mechanism which is the object of this paper. During the course of an antigen-specific immune response, the affinity of the serum increases with time, a phenomenon commonly referred to as maturation of the response (Jerne 1951, Siskind & Benaceraff 1969). Such a maturation results from specific alterations of the structure of the antibody molecules (Steiner & Eisen 1967). What is the precise nature of these alterations, which are the root of the production of high affinity antibodies? There is no doubt that somatic mutation contributes to antibody diversity (Weigert et al. 1970. Bernard et al. 1978, Griffiths et al. 1984). There are many reasons to believe that a mechanism of hypermutation operates within restricted stretches of the DNA to further diversify the genes encoding the antibody molecules (Kim et al. 1981, Gearhart & Bogenhagen 1983). This mutational drift is, however, not the full extent of the change. Major changes in the antibody structures involved result from a shift in the antigen-specific B-cell repertoire over the course of the immune response. In the primary response the most frequent B-cell clones already expressing antibody molecules with a relatively

Lymphocyte recognition of high endothelium: antibodies to distinct epitopes of an 85-95-kD glycoprotein antigen differentially inhibit lymphocyte binding to lymph node, mucosal, or synovial endothelial cells.

Abstract: The tissue-specific homing of lymphocytes is directed by specialized high endothelial venules (HEV). At least three functionally independent lymphocyte/HEV recognition systems exist, controlling the extravasation of circulating lymphocytes into peripheral lymph nodes, mucosal lymphoid tissues (Peyer9s patches or appendix), and the synovium of inflamed joints. We report here that antibodies capable of inhibiting human lymphocyte binding to one or more HEV types recognize a common 85-95-kD lymphocyte surface glycoprotein antigen, defined by the non-blocking monoclonal antibody, Hermes-1. We demonstrate that MEL-14, a monoclonal antibody against putative lymph node "homing receptors" in the mouse, functionally inhibits human lymphocyte binding to lymph node HEV but not to mucosal or synovial HEV, and cross-reacts with the 85-95-kD Hermes-1 antigen. Furthermore, we show that Hermes-3, a novel antibody produced by immunization with Hermes-1 antigen isolated from a mucosal HEV-specific cell line, selectively blocks lymphocyte binding to mucosal HEV. Such tissue specificity of inhibition suggests that MEL-14 and Hermes-3 block the function of specific lymphocyte recognition elements for lymph node and mucosal HEV, respectively. Recognition of synovial HEV also involves the 85-95-kD Hermes-1 antigen, in that a polyclonal antiserum produced against the isolated antigen blocks all three classes of lymphocyte-HEV interaction. From these studies, it is likely that the Hermes-1-defined 85-95-kD glycoprotein class either comprises a family of related but functionally independent receptors for HEV, or associates both physically and functionally with such receptors. The findings imply that related molecular mechanisms are involved in several functionally independent cell-cell recognition events that direct lymphocyte traffic.

Development and Characterization of Breast Cancer Reactive Monoclonal Antibodies Directed to the Core Protein of the Human Milk Mucin

Abstract: A mucin molecule, which has a molecular weight of greater than 400,000 and which carries tumor associated epitopes recognized by monoclonal antibodies HMFG-1 and HMFG-2, has been purified from human skimmed milk by affinity chromatography followed by passage through a size exclusion column. While treatment of the mucin with hydrogen fluoride for 1 h at 4°C removed the peripheral oligosaccharides, treatment with HF for 3 h at room temperature removed all of its lectin binding ability and revealed a dominant polypeptide of about 68,000. This appears to be the size of the mucin core protein. Monoclonal antibodies have been developed that react with the stripped and partially stripped molecule but not with the intact mucin. From the initial screening on histological sections one of these antibodies, SM-3, reacts with 91% of breast carcinomas but shows little or no reactivity on benign mammary tumors, normal resting, pregnant, or lactating breast. It appears that this monoclonal antibody is reacting with an epitope that is usually masked by oligosaccharide moieties in normal cells but which is exposed, perhaps due to aberrant glycosylation, in malignant cells.

Identification and specificity of a cDNA encoding the 70 KD mitochondrial antigen recognized in primary biliary cirrhosis

Abstract: Mitochondrial autoantibodies are characteristic of the disease primary biliary cirrhosis (PBC), but the immunoreactive mitochondrial antigens have not been defined. We used a rat liver cDNA library in lambda gt 11-Amp3 to clone a 1370-base pair insert that coded for a polypeptide reactive with PBC sera. This insert was subcloned for expression into pBTA224, a plasmid vector in the same reading frame as lambda-Amp3. A positive clone, designated pRMIT, that expressed a fused polypeptide of 160 kd, was recognized by 25 of 25 sera from patients with PBC and none of 96 sera from normal persons or patients with systemic lupus erythematosus, rheumatoid arthritis, or chronic active hepatitis. This fused polypeptide was shown to correspond with the 70 kd mitochondrial autoantigen by several experiments. First, lysates of pRMIT in J101 absorbed out the 70 kd reactivity of PBC sera when probed against fractionated placental mitochondria. Second, affinity-purified antisera reactive with the fused polypeptide also reacted with the 70 kd mitochondrial antigen. Third, such affinity-purified antisera produced the characteristic anti-mitochondrial pattern of immunofluorescence on tissue sections. Finally, immunization of BALB/c mice with the fused polypeptide elicited antibodies to mitochondria. These murine antibodies reacted with the 70 kd mitochondrial protein and also produced typical mitochondrial immunofluorescence on tissue sections. The nucleotide and amino acid sequence of the recombinant protein, which encodes for approximately a 48 kd protein, showed no significant homologies with known proteins, and there were no homologies with mitochondrial genomic DNA. The availability of a recombinant form of the 70 kd mitochondrial autoantigen will allow several definitive questions to be addressed in PBC, including identification of B cell epitopes, T cell recognition, and a model of PBC in mice.

Interleukin 2 high-affinity receptor expression requires two distinct binding proteins.

Abstract: A cell line established from a patient with acute lymphoblastic leukemia was found to express IL-2 binding sites with a novel, intermediate affinity compared with the characteristic high-affinity IL-2-receptors and low-affinity IL-2 binding sites described previously. Clones were isolated from this cell line that displayed solely this new IL-2-binding protein, and were found to be unreactive with anti-Tac, the mAb that competes with IL-2 for binding. Moreover, these same cloned cells did not express mRNA detectable by hybridization with radiolabeled cDNA encoding the Tac protein. In contrast, the original cell line and similar clones expressed low levels of Tac mRNA and cell surface Tac antigen, both of which could be augmented by exposure to medium conditioned by adult T leukemia cell lines. Particularly noteworthy, induction of Tac antigen expression was paralleled by an increase in the number of high-affinity IL-2-R detectable. Since the expression of the Tac antigen protein by itself makes only for low-affinity IL-2 binding, these data prompted a reevaluation of the structural composition of high-affinity IL-2-R. Analysis of the IL-2-binding proteins expressed by leukemic cell lines lacking high-affinity receptors revealed only a single protein, larger than the Tac antigen protein (Mr = 75,000 vs. 55,000). In contrast, clones induced to express high-affinity receptors had clearly both of these IL-2-binding proteins. Moreover, when IL-2 binding to normal T cells was performed under conditions that favored the proportion of high-affinity receptors occupied, two distinct proteins identical to those already identified on the leukemic cells could be crosslinked covalently to radiolabeled IL-2. The interpretations derived from these varied, assembled data, point to two IL-2-binding proteins, both of which are required for high-affinity IL-2 binding.

Human lymphocytes making rheumatoid factor and antibody to ssDNA belong to Leu-1+ B-cell subset

Abstract: B lymphocytes bearing the Leu-1 cell-surface antigen (Leu-1+), the human equivalent of mouse Ly-1+ B lymphocytes, have been detected in human peripheral blood, but there is little information on their frequency and properties. Analysis by fluorescence-activated cell sorter and double immunofluorescence showed that Leu-1+ B cells are consistently present in the peripheral blood and spleens of healthy subjects and constitute 17.0 +/- 5.0% (mean value +/- standard deviation) and 17.3 +/- 3.9%, respectively, of total B cells. When purified Leu-1+ and Leu-1- B lymphocytes were transformed into immunoglobulin-secreting cells by infection with Epstein-Barr virus and the culture fluids were tested for reactivity with self-antigens, at least two important autoantibodies, antibody to the Fc fragment of human immunoglobulin G (rheumatoid factor) and antibody to single-stranded DNA, were found to be made exclusively by Leu-1+ B cells. It is concluded that the Leu-1+ lymphocytes represent a major subset of the normal human B cell repertoire and include the B cells capable of making autoantibodies similar to those found in systemic lupus erythematosus and rheumatoid arthritis.

Structure and function of anti-DNA autoantibodies derived from a single autoimmune mouse

Abstract: Four monoclonal anti-DNA antibodies derived from a single autoimmune MRL/lpr mouse were studied. Three of these antibodies showed similarities in DNA binding; the fourth had a much higher specific activity for single-stranded DNA and, in addition, was unique in binding double-stranded DNA and cardiolipin. Complete nucleotide sequences of heavy- and light-chain variable regions demonstrated that all four antibodies are clonally related. The sequences also showed numerous somatic mutations, the distribution of which suggests that positive selection by antigen operated on these clonally related autoantibodies.

A monoclonal antibody (HML-1) defining a novel membrane molecule present on human intestinal lymphocytes

Abstract: A monoclonal antibody, HML-1, was produced by fusion of NSI myeloma cells with spleen cells of a mouse immunized with isolated human intestinal intraepithelial lymphocytes (IEL). Immunofluorescence studies of isolated cells, as well as immunoperoxidase staining of tissue sections, indicated that HML-1 labeled all the various subsets of human intestinal IEL, approximately 40% of lamina propria T cells, 30% mesenteric lymphoblasts and some lymphocytes in other mucosae, particularly IEL. Conversely, it revealed only rare cells in all other lymphoid compartments. Analysis by polyacrylamide gel gradient electrophoresis showed that HML-1 precipitated two major noncovalently bound components of approximate mol. masses of 105 and 150 kDa from human IEL. HML-1 thus defines a novel human membrane antigen present on a subpopulation of lymphocytes preferentially associated with epithelia, and particularly with the intestinal epithelium. The characteristics of this human antigen are very similar to those of an antigen we had previously described in the rat. The possible functional role of this novel class of lymphocyte membrane antigens as well as the nature of the mechanism that triggers their expression remain to be elucidated.

IgG2a restriction of murine antibodies elicited by viral infections.

Abstract: The isotypic distribution of IgG antibodies was determined in the serum of mice after infection with a panel of RNA and DNA viruses representative of 11 different genera. The antiviral response induced by all these viruses showed a striking preponderance of the IgG2a subclass whatever the strain of mice tested or the time elapsed after infection. Together with the predominance of IgG1 in antiprotein and of IgG3 in anticarbohydrate response, this IgG2a restriction of antiviral antibodies strongly suggests the existence of highly specific mechanisms for the regulation of individual subclasses in the mouse.

HHF35, a muscle-actin-specific monoclonal antibody. I. Immunocytochemical and biochemical characterization.

Abstract: A monoclonal antibody to muscle cell actin isotypes was produced and characterized. Immunocytochemical analysis of methanol-Carnoy's-fixed, paraffin-embedded human tissue revealed that this antibody, termed HHF35, reacts with skeletal muscle cells, cardiac muscle cells, smooth muscle cells, pericytes, and myoepithelial cells, but is nonreactive with endothelial, epithelial, neural, or connective tissue cells. When assayed by indirect immunofluorescence, HHF35 reacts with microfilament bundles from various cultured mammalian smooth muscle cells, but does not react with cultured human dermal fibroblasts or various epithelial tumor cell lines. In one-dimensional gel electrophoresis immunoblot experiments this antibody detects a 42-kd polypeptide from tissue extracts of uterus, ileum, aorta, diaphragm, and heart and extract from smooth muscle cells. The antibody also reacts with a comigrating 42-kd band of highly purified rabbit skeletal muscle actin. HHF35 is nonreactive on immunoblots of extracts from all tested nonmuscle cell extracts. Immunoelectrophoresis followed by immunoblotting performed in the presence of urea and reducing agents reveals recognition of the alpha isoelectrophoretic variant of actin from skeletal, cardiac, and smooth muscle sources and of the gamma variant from smooth muscle sources. Because HHF35 reacts with virtually all muscle cells, it will be useful as a marker for muscle and muscle-derived cells.