Showing papers on "Antigen published in 1976"

Cross-priming for a secondary cytotoxic response to minor H antigens with H-2 congenic cells which do not cross-react in the cytotoxic assay.

Abstract: Cytotoxic effector T cells of F1 (BALB/c X BALB.B) (H-2d/b) mice immunized against the minor histocompatibility differences of C57BL/10 (H-2b) can lyse targets from C57BL/10, but cannot lyse B10.D2 (H-2d) targets. Despite this lack of cross-reaction in the cytotoxic assay, C57BL/10 cells do prime F1 (BALB/c X BALB.B) mice for a secondary cytotoxic response to B10.D2. C57BL/10-primed, B10.D2-boosted cytotoxic cells lyse B10.D2 targets but not C57BL/10 targets. DBA/2 (H-2d) spleen cells or thymocytes prime F1 mice for a secondary response to DBA/2, B10.D2, and C57BL/10 cells, but DBA/2 mastocytes, P815, do not prime for a response to C57BL/10. Whether H-2 congenic lymphoid cells express minor histocompatibility determinants which cross-react at the cytotoxic T-cell level or the helper T-cell level is discussed.

E Antigen and Anti-E in the Serum of Asymptomatic Carrier Mothers as Indicators of Positive and Negative Transmission of Hepatitis B Virus to Their Infants

Abstract: Testing of serum samples of 23 pregnant women who were asymptomatic carriers of hepatitis B surface antigen for e antigen and antibody to e with an immunodiffusion technic identified 10 mothers with e antigen and seven with e antibody. Their babies were tested for hepatitis B surface antigen in serum at intervals for more than 12 months. In all 10 babies born to e-antigen-positive mothers hepatitis B surface antigen developed and persisted through the observation period, and all 10 elder siblings of these newborn babies were found to be asymptomatic carriers. In remarkable contrast, all seven babies born to mothers positive for antibody to e escaped antigenemia, and none of their three elder siblings carried surface antigen. On the basis of these results, e antigen may be used as an indicator of transmission, and antibody to e as that of absence of transmission of hepatitis B virus from carrier mothers to children. (N Engl J Med 294: 746–749, 1976)

Correlation of Maternal Antibody Deficiency with Susceptibility to Neonatal Group B Streptococcal Infection

Abstract: We investigated the role of maternal antibody in neonatal Group B streptococcal infection with a radioactive antigen-binding assay employing a purified polysaccharide antigen with both Type III and Group B determinants. Serums from seven women who gave birth to infants who had invasive Group B streptococcal infection with Type III strains were all deficient in antibody. In contrast, serums from 22 of 29 pregnant Type III vaginal carriers whose infants were healthy contained antibody with a prevalence significantly different from that in women delivering infants with Type III disease (P < 0.01). Three healthy neonates born to women with antibody in serums had demonstrable antibody in umbilical-cord serum. These data suggest that transplacental transfer of maternal antibody protects infants from invasive Group B streptococcal infection with Type III strains. (N Engl J Med 294:753–756, 1976)

Effect of Human Leukocyte Interferon on Hepatitis B Virus Infection in Patients with Chronic Active Hepatitis

Abstract: Four patients with chronic hepatitis B infection and chronic active hepatitis were treated with human leukocyte interferon. Three of them had consistently elevated levels of circulating Dane-particle markers, including Dane-particle-associated DNA polymerase activity, hepatitis B core antigen and Dane-particle-associated DNA. Parenteral interferon administration at a dosage between 6.0 X 10(3) and 17 X 10(4) U per kilogram per day was associated with a rapid and reproducible fall in all Dane-particle markers in the three patients. The suppressive effect was transient when the interferon was given for 10 days or less but appeared to be more permanent when administration was prolonged for a month or more. In addition, long-term interferon therapy was associated with a marked fall in hepatitis B surface antigen in two of three patients and a disappearance of e antigen in two of two patients. Interferon may be useful in limiting carrier infectivity or eradicating chronic infection.

Cell membrane antigen isolation with the staphylococcal protein A-antibody adsorbent.

Abstract: Procedures are detailed for the rapid isolation of representative cell membrane antigens with protein A-bearing staphylococci as an adsorbent for IgG antibodies complexed with the antigens. Cell surface membrane proteins were radioiodinated and solubilized in nonionic detergent. Specific antisera were subsequently added and the immune complexes precipitated by addition of the staphylococcal adsorbent and low speed centrifugation. The antigens isolated included surface immunoglobulins from mouse and human lymphocytes, human beta-microglobulin and HL-A alloantigens, mouse H-2 alloantigens, and the murine leukemia virus glycoprotein gp 70. Rabbit, sheep, goat, and mouse antisera were all effective for the specific phase of the precipitation reaction. The surface membrane immunoglobulins of mouse splenic lymphocytes and human peripheral blood lymphocytes differed with respect to class composition and protein A reactivity. Mouse lymphocyte surface immunoglobulins were nonreactive with protein A, whereas a high proportion of human lymphocyte surface immunoglobulins of different classes bound directly to the staphylococci. In sequential immunoprecipitation studies the prior isolation of one antigen had no appreciable effect on the subsequent recovery of another antigen. Adsorption of antigen-antibody complexes is quantitative when protein A sites are provided in excess over antiserum IgG sites, and this obviates the need for equivalence point titrations for optimal precipitation necessary with alternative double antibody techniques.

Suppressor cell activity after concanavalin A treatment of lymphocytes from normal donors.

Abstract: Pretreatment of normal human peripheral blood lymphocytes with the plant lectin, concanavalin A (Con A), results in inhibition of blast transformation and [3H]thymidine incorporation by untreated allogeneic lymphocytes from healthy volunteers donors in one-way mixed leukocyte culture. Similarly, responses to mitogens, certain microbial antigens, and allogeneic lymphocytes are inhibited by Con A-treated allogeneic cells. Con A pretreated autologous lymphocytes can also be induced to manifest suppressor activities. This antimitotic effect occurs without evidence of cytotoxicity and is active on de novo lymphocyte responses and does not require prior sensitization of the cells being tested. Suppression of the lymphocyte response to pokeweed mitogen, a potent B-cell stimulator, by Con A-pretreated suppressor cells was not as consistent as was inhibition of response to other mitogens, including phytohemagglutinin and Con A. Furthermore, suppression of lymphocyte transformation to the microbial antigens, tuberculin purified protein derivative, and Canadida albicans extracts could be similarly induced by Con A pretreatment of either allogeneic or autologous cells. Induction of autologous suppressor activity in lymphocytes from healthy donors is compatible with a model that includes a role for suppressor cells in the modulation of the normal immune response.

Differential function of major histocompatibility complex antigens in T-lymphocyte activation.

Abstract: The antigenic systems of the major histocompatibility complex can be subdivided into those which are serologically detectable and those which are detected in tests with mixed lymphocytes. The two systems have different roles in the activation of separate populations of T lymphocytes.

Early production of intracellular IgM by B-lymphocyte precursors in mouse.

Abstract: IN BALB/c mice, surface immunoglobulin (Ig)-bearing B lymphocytes are first detectable by immunofluorescence at 17 d gestation in the liver and spleen1. Explants of 14-d foetal liver1 and spleen2, and 15-d bone marrow (our unpublished observations), have been shown to generate Ig-bearing B cells in vitro after 4–7 d of culture, suggesting that B lymphocytes normally develop multifocally in the haemopoietic tissues of mice. We have used direct immunofluorescence to demonstrate cells with intracellular IgM and no detectable surface Ig in mouse foetal liver as early as 12 d gestation. Our results suggest that B lymphocyte precursors synthesise IgM several days before they incorporate these molecules into their plasma membranes as cell-surface receptors for antigen.

Cell surface antigens of human malignant melanoma: mixed hemadsorption assays for humoral immunity to cultured autologous melanoma cells.

Abstract: We studied how frequently patients with malignant melanoma have specific antibody to cell surface antigens of cultured autologous melanoma cells as demonstrated by mixed hemadsorption assays. Of 35 patients studied over periods ranging from 1 to 36 months with Stage II, III, and IV disease, two showed consistent and high titered reactivity against autologous melanoma cells, two showed less consistent and intermediate reactivity, seven showed sporatic, low titered reactivity, and the remainder were consistently negative. A detailed analysis was carried out with the sera of one patient with sufficiently high titer against autologous melanoma cells. By direct tests and by absorption analysis with a variety of melanoma and nonmelanoma cell lines which included autologous fibroblasts, the antigen could not be demonstrated on any cell type other than the autologous melanoma.

Association of antibodies to ribonucleoprotein and Sm antigens with mixed connective-tissue disease, systematic lupus erythematosus and other rheumatic diseases.

Abstract: Extractable nuclear antigen contains ribo-nuclease-sensitive (ribonucleoprotein) and ribonuclease-resistant (Sm) components. To determine the diagnostic usefulness of antibodies to these antigens, a multicenter study was undertaken in which serums were analyzed for these antibodies and the findings compared with clinical and other laboratory characteristics of the patients. Of 100 patients with hemagglutinating antibodies to ribonuclease-sensitive extractable nuclear antigen, and only the same antibodies by immunodiffusion, 74 per cent had typical features of mixed connective-tissue disease; 12 features of systemic lupus erythematosus, eight those of scleroderma and six an undifferentiated mild connective-tissue disease. Of 27 patients with hemagglutinating antibodies to ribonuclease-resistant extractable nuclear antigen (and Sm antibodies by immunodiffusion), 85 per cent had typical systemic lupus. Thus, antibodies to nuclear ribonucleoprotein and Sm are of diagnostic use; if the serum contains only ribonucleoprotein antibody in high titer, it is likely that the patient has mixed connective-tissue disease.

Identification of antibodies to nuclear acidic antigens by counterimmunoelectrophoresis

Abstract: Saline extracts of rabbit thymus were found to contain many nuclear antigens that reacted with antibodies in the sera of patients with systemic rheumatic diseases. Counterimmunoelectrophoresis (CIE) was used to detect antibodies to nuclear acidic protein (Sm), nuclear ribonucleoprotein (RNP), and antibody to nuclear antigen B, which was reported previously in Sjogren's syndrome. All these nuclear antigens behaved as anions with different mobilities in CIE and could be distinguished from one another by the locations of the precipitin lines. They could also be distinguished by the facts that the nuclear RNP precipitin lines were abolished by digestion with ribonuclease whereas others were unaffected, and that Sm precipitin lines developed later than other precipitin lines. With this technique antibody to nuclear RNP was detected in 46% of patients with systemic lupus erythematosus (SLE) compared to 26% detected by the hemagglutination technique. Similarly the increased sensitivity of the CIE technique was able to show that antibody to B antigen was present in 12% of SLE patients, whereas this antibody was not detectable in the same group of patients by immunodiffusion. This study shows that CIE is a rapid and sensitive technique for detecting precipitating antibodies to a number of nuclear acidic antigens. Methods are described to identify the immunochemical specificities of the precipitin lines by the use of standard reference sera.

Type B hepatitis: the infectivity of blood positive for e antigen and DNA polymerase after accidental needlestick exposure

Abstract: To determine the relation between the presence of donor DNA polymerase and e antigen, and recipient hepatitis, we tested, under code, serums from a controlled trial of hepatitis B immune globulin used to treat individuals accidentally inoculated with HBs Ag-positive blood. All recipients lacked antibody to HBs Ag. In 29 of 31 donors, both polymerase and e were in perfect agreement; both demonstrated a highly significant correlation with recipient hepatitis (P less than 0.001). DNA polymerase/e-negative blood did not cause hepatitis. Blood containing polymerase or e antigen did not cause hepatitis in six of 31 and four of 18 recipients, respectively. Hepatitis did not correlate with transaminase or duration of antigenemia in the donor. Polymerase and e appear to be indicators of the relative infectivity of HBs Ag-positive serum, particularly after small-volume exposure. They may be important determinants in assessing infectivity of chronic carriers of HBs Ag and in evaluating efficacy of hepatitis B immune globulin and hepatitis B vaccines.

Properties of the antigen-specific suppressive T-cell factor in the regulation of antibody response of the mouse. IV. Special subregion assignment of the gene(s) that codes for the suppressive T-cell factor in the H-2 histocompatibility complex.

Abstract: Preceding papers in this series indicated that the suppression of antibody response by thymus-derived lymphocytes (T cells) involves a complementary interaction of cell surface molecules of different subsets of T cells which are encoded by genes located within the major histocompatibility (H-2) complex of mice (1-5). This has been shown by two lines of experiments: (a) The molecule which suppresses the antibody response of syngeneic or H-2 histocompatible mouse strains can be absorbed with alloantisera raised against the products of genes in the H-2 complex of the same haplotype. (b) The above suppressive molecule of T cells can effectively suppress the antibody response of H-2 histocompatible mouse strains but not that of H-2 histoincompatible strains. Thus, the identities among genes in the H-2 complex between the donor of the suppressive molecule and its target cells are definitely required for the induction of an effective suppression. The results led us to postulate that the suppression by T cells is controlled by at least two genes both located within the H-2 complex, and a complementary interaction of the products of these two genes plays an essential part ofT-cell-mediated suppression of the antibody response (3). Further studies demonstrated that the suppressive T-cell-derived molecule is, in fact, an/-region gene product in H-2 ~, H-2 ~, and H-2 8 mice (4), although the exact location of such genes in the I region was not determined. It was also shown that the acceptor site for the suppressive T-cell factor is encoded by genes in the left side half (K, I-A, and I-B subregions) of H-2 complex (3-5). Both expressions of suppressor and acceptor genes were found to be dominant traits. It has been well established that/-region genes code for surface molecules on lymphoid and other cell types, which are distinct from H-2 histocompatibility antigens (6-12). They are designated as Ia antigens being detectable by certain alloantisera raised by immunization of mouse strains sharing only K and D alleles in the H-2 complex. The Ia molecules have multiple antigenic determi

Membrane and Cytoplasmic Changes in B Lymphocytes Induced by Ligand-Surface Immunoglobulin Interaction

Abstract: Publisher Summary This chapter discusses membrane and cytoplasmic changes in B lymphocytes induced by ligand–surface immunoglobulin (Ig) interaction. Surface Ig is the receptor for antigen molecules on B lymphocytes. Surface Ig has been identified on the B-cell surface by using immunocytochemistry or direct biochemical analysis. The number of Ig molecules presumably serving as antigen receptors on the B cell surface is on the average of 105 molecules per B cell. The amount of surface-bound Ig is large comparing to the number of hormone receptors needed to trigger certain cellular responses. One could speculate that many of the surface Ig–antigen interactions result in nonfunctional events; therefore, many receptors are needed. The B cell requires such a high number of receptors to effectively bind antigen molecules of large size and variable epitope densities or a number of successive hits are needed in these cells to reach an effective threshold of stimulation. The distribution of surface Ig and other surface macromolecules has been studied at the ultrastructural level by using various methods. One method was the ultrastructural analysis of regular thin section of cells exposed to antibodies conjugated to a large visible molecule.

Regulation of the Immune Response to Tumor Antigens I. Immunosuppressor Cells in Tumor-Bearing Hosts

Abstract: Together these results suggest that TBA possess immunosuppressor T cells regulating negatively their immune response to the tumor

Separation of helper T cells from suppressor T cells expressing different Ly components. II. Activation by antigen: after immunization, antigen-specific suppressor and helper activities are mediated by distinct T-cell subclasses.

Abstract: Cells of the Lyl subclass generate helper activity in both primary and secondary responses to sheep erythrocytes (SRBC). In contrast, after priming with SRBC, cells of the Ly-2+ subclasses, in particular Ly23 cells, have suppressive activity. The degree of Ly23-mediated suppression is directly proportional to the amount of antigen (SRBC) used for priming. Suppression by Ly23 cells is specific, because Ly23 cells from SRBC-primed animals do not suppress the response to horse erythrocytes, and vice versa. Thus, both cytotoxic and specific suppressor functions are mediated by T cells of a subclass, provisionally designated TCS, which can be distinguished from helper T cells (TH), by their Ly phenotypes. It remains to be determined whether killing and suppression are functionally interrelated properties of a single Ly23 subclass, or whether the Ly23 population comprises two subclasses whose surface phenotypes are not yet distinguishable by immunogenetic criteria.

An Improved Method for Isolation of H-2 and Ia Alloantigens with Immunoprecipitation Induced by Protein A-Bearing Staphylococci

Abstract: Mouse alloantigens, including the histocompatibility (H-2) and immune response linked (Ia) antigen molecules, can be readily isolated by a new precipitation technique utilizing protein A-bearing, fixed Staphylococci. The antigens are prepared by radiolabeling mouse spleen cells with 3H-leucine, solubilizing with the non-ionic detergent Non-Idet P-40, and purifying by affinity chromatography with lentil lectin coupled to Sapharose. The antigen preparations are mixed with appropriate alloantisera, and immune complexes formed in the mixture are then bound by the protein A sites on the Staphylococci. The organisms, Staphylococcus aureus, Cowan I strain (ATCC 12598), are heat inactivated and fixed, and are a stable, uniform IgG-binding reagent, especially when stored frozen. The antigen-antibody complexes are easily eluted from the organisms for electrophoretic analysis. The precipitation mediated by the organisms is more efficient, rapid, and artifact-free than the traditional "sandwich" precipitation technique involving anti-globulin reagents.

Distribution of Ia-like molecules on the surface of normal and leukemic human cells.

Abstract: Antiserum to a glycoprotein antigen complex of 23,000 and 30,000 dalton subunits (p23,30), isolated and purified from a human lymphoblastoid B cell line, was shown to be highly specific for human bursal-equivalent-processed (B) cells, reactive with 15-20% of human Null cells, but completely unreactive with human thymus-processed (T) cells. The p23,30 antigen is widely distributed on chronic lymphatic leukemic cells, 85% of acute lymphatic leukemic cells, all acute myelogenous leukemic cells, but not on chronic myelogenous leukemic cells. A rabbit antiserum specific for normal human thymocytes has also been prepared; it is reactive only with precisely that subset of acute lymphatic leukemic cells (15%) whose members do not have p23,30 on their surfaces.

Hepatitis B surface antigen produced by a human hepatoma cell line.

Abstract: The human hepatoma cell line, PLC/PRF/5, was shown to produce hepatitis B surface antigen (HBsAg). Immunologically reactive material was present in the supernatant tissue culture medium in significant amounts, and was associated with spherical particles approximately 20 nm in diameter. The rate of antigen production by the cells was estimated at 500 ng/day/10(6) cells by reference to a purified HBsAg standard. All immunological activity was neutralized by specific antibody and the subtype was ad. The studies reported here broaden the scope of investigations on both the in vitro production of HBsAg and the association between this antigen and primary liver cancer.

Studies on the mechanism of phagocytosis. II. The interaction of macrophages with anti-immunoglobulin IgG-coated bone marrow-derived lymphocytes.

Abstract: We have examined the effect of the distribution of anti-immunoglobulin IgG molecules on the surface of bone marrow-derived lymphocytes upon the interaction of these cells with macrophages. Lymphocytes which were diffusely coated with antibodies to surface immunoglogulin were ingested by macrophages. Lymphocytes which had the same number of anti-immunoglobulin IgG molecules redistributed to one pole of the surface bound to the macrophages' Fc receptors but were not ingested. These results confirm our previous hypothesis that ingestion of an immunologically coated particle requires the sequential, circumferential binding of specific receptors on the plasma membrane of a phagocytic cell to immunologic ligands distributed over the entire particle surface. Macrophages which had bound capped lymphocytes by the macrophages' Fc receptors removed the immune complex caps from the lymphocyte surface without destroying the lymphocytes. These lymphocytes remained attached to the macrophage surface. The finding that macrophages can phagocytize immune complexes from the surface of a cell without destroying the cell to which these complexes are attached may be important in understanding the effects of antigens and antibodies on cells participating in a humoral immune response, in identifying the mechanisms by which chronic viral infections are established, and in defining the roles of blocking antibodies in tumor immunity.

Minor H Antigens Introduced on H-2 Different Stimulating Cells Cross-React at the Cytotoxic T Cell Level during in Vivo Priming

Abstract: The cellular basis of the cross-priming observed with minor histocompatibility antigens on H-2 different cells was investigated. Cytotoxic T cells induced against minor alloantigens show absolute H-2 restriction at the effector level ([51Cr]-release). That is, F1 (BALB/c X BALB.B) (H-2d/b) cytotoxic cells induced by immunization with B10(H-2b) cells are not able to lyse B10.D2(H-2d) targets. But an injection of B10 cells does prime F1 mice for a secondary cytotoxic response to B10.D2. The technique of inducing cytotoxic effector function polyclonally with Con A in the absence of alloantigen was used here to establish that such cross-priming reflects what happens at the cytotoxic cell level. It is shown that an F1 animal previously injected with B10 cells has expanded pools of memory cytotoxic cells reactive with B10 and B10.D2. From this it is concluded that: a) minor H structures on B10.D2 and B10 do cross-react at the cytotoxic T cell level during in vivo priming, and b) because normal cells cross-prime whereas tumor cells do not, then the F1 cytotoxic precursors are probably committed to respond to antigen on cells bearing either the maternal or paternal H-2 haplotype before they encounter antigen. Cross-priming may be explained by foreign minor H antigens being presented to F1 host T cells on the surface of host macrophages. Therefore priming is not restricted to the H-2 type of the injected cells but to both H-2 types of the F1 host.

In vitro tolerance induction of neonatal murine B cells.

Abstract: The susceptibility of neonatal and adult B lymphocytes to tolerance induction was analyzed by a modification of the in vitro splenic focus technique. This technique permits stimulation of individual hapten-specific clonal precursor cells from both neonatal and adult donors. Neonatal or adult BALB/c spleen cells were adoptively transferred into irradiated, syngeneic, adult recipients which had been carrier-primed to hemocyanin (Hy), thus maximizing stimulation to the hapten 2,4-dinitrophenyl coupled by Hy (DNP-Hy). Cultures were initially treated with DNP on several heterologous (non-Hy) carriers and subsequently stimulated with DNP-Hy. Whereas the responsiveness of adult B cells was not diminished by pretreatment with any DNP conjugate, the majority of the neonatal B-cell response was abolished by in vitro culture with all of the DNP-protein conjugates. During the 1st wk of life, the ability to tolerize neonatal splenic B cells progressively decreased. Thus, tolerance in this system is: (a) restricted to B cells early in development; (b) established by both tolerogens and immunogens; (c) achieved at low (10(-9) M determinant) antigen concentrations; and (d) highly specific, discriminating between DNP- and TNP-specific B cells. We conclude that: (a) B lymphocytes, during their development, mature through a stage in which they are extremely susceptible to tolerogenesis; (b) the specific interaction of B-cell antigen receptors with multivalent antigens, while irrelevant to mature B cells, is tolerogenic to neonatal (immature) B cells unless antigen is concomitantly recognized by primed T cells; and (c) differences in the susceptibility of immature and mature B lymphocytes to tolerance induction suggest intrinsic differences between neonatal and adult B cells and may provide a physiologically relevant model for the study of tolerance to self-antigens.

Separation of helper T cells from suppressor T cells expressing different Ly components. I. Polyclonal activation: suppressor and helper activities are inherent properties of distinct T-cell subclasses.

Abstract: Concanavalin A, a nonspecific polyclonal activator of T lymphocytes, activates Lyl and Ly23 subclasses to the same degree. After activation, the Ly23 subclass, but not the Lyl subclass, has the following properties: (a) Suppression of the antibody response to sheep erythrocytes (SRBC) in vitro. (b) Production of a soluble factor that suppresses the anti-SRBC response in vitro. (c) Suppression of the generation of cell-mediated cytotoxicity to H-2 target cells in vitro. Con A-activated cells of the Lyl subclass, but not the Ly23 subclass, express helper function in the anti-SRBC response in vitro. Because the intact Con A-stimulated T-cell population contains both cell types, these cells do not exert detectable helper effects in an anti-SRBC system in vitro, because the helper effect of Lyl cells is masked by the suppressor effect of the Ly23 cells. Each function is revealed by eliminating one or the other population with the relevant Ly antiserum. The resting T-cell population, before activation by Con A, also contains already programmed Lyl and Ly23 cells with similar helper and suppressor potentials, respectively. This is revealed by experiments with Ly subclasses which have been separated from the resting T-cell population and then stimulated by Con A. Thus helper and suppressor functions, as expressed in these systems, are manifestations of separate T-cell-differentiative pathways and do not depend upon stimulation of the cells by antigen.

Lymphocyte stimulation by protein A of Staphylococcus aureus.

Abstract: Protein A from Staphylococcus aureus (SpA) is known to bind to the Fc region of most mammalian IgG classes. In the present article data are presented showing that SpA is a highly efficient mitogen for human peripheral B lymphocytes, with no detectable activity for T lymphocytes. In order to achieve optimal stimulating conditions SpA should be presented to the lymphocytes on an insoluble matrix, such as the SpA-positive bacteria themselves or SpA covalently attached to Sephadex or Sepharose beads. Using such conditions SpA is equivalent with regard to stimulatory capacity for B lymphocytes as phytohemagglutinin is for the human T lymphocytes. Specificity controls proved beyond doubt that SpA and not any other contaminating product is the B cell mitogen. It is concluded that SpA as an inducer of human B lymphocyte division might serve as a highly useful assay in the clinical assessment of B lymphocyte function. It should also be a suitable tool in the fine analysis of B lymphocyte activation via the specific interactions with surface IgG molecules.

Regulation of the immune response to tumor antigens. II. The nature of immunosuppressor cells in tumor-bearing hosts.

Abstract: Immunosuppressor (IS) cells were found to be generated in tumor-bearing animals (TBA) within 24 hr after inoculation of tumor cells of the methylcholanthrene-induced Sarcoma 1509a and appeared to persist in the hosts as long as the tumor was progressing. However, IS cells disappeared with 5 days after extirpation of the tumor. Increasing doses of thymus cells of TBA increased the degree of suppression of tumor rejection in immune syngeneic animals. Ten million thymus cells of TBA were capable of suppressing significantly the tumor rejection. The IS cells were detected in the thymuses, spleens, and draining lymph nodes, as well as in bone marrow of TBA, but could not be detected in the peripheral circulating blood. Since immunosuppressive activity of bone marrow cells from TBA was entirely abolished by the in vitro treatment of the cells with anti-θ serum and complement, the observed immunosuppression appears to be mediated by the T cell population. Hydrocortisone treatment of TBA did not abolish the suppressive activity of the thymus or spleen cells of the treated TBA, thus suggesting that IS cells were cortisoneresistant. The suppressive activity was found to be associated with cells of lowest density on centrifugation through a discontinuous density gradient of Ficoll. The results of this study, taken together with those presented in the preceding article, suggest that IS cells belong to a T cell subpopulation (immunosuppressor T cells). The relationships between immunosuppressor T cells and other T cell subpopulations, i.e., cytotoxic (effector) or helper (amplifier) T cells, remain to be elucidated in further experiments.

Suppressor thymus-derived lymphocytes in fungal infection.

Abstract: Thymus-derived lymphocyte (T-cell) function, as determined in vivo by cutaneous reactivity to several antigens and in vitro by responsiveness to mitogens and antigens, was assessed in 14 patients infected with a variety of fungal organisms. While all patients manifested a normal frequency of peripheral blood T cells, only seven patients reacted to at least one of the antigens used for cutaneous testing and demonstrated normal in vitro T proliferative responses. Three patients exhibited cutaneous anergy but normal in vitro T-cell reactivity while four patients demonstrated persistent anergy and marked in vitro T-cell hyporeactivity which was independent of activity of infection, concurrent medication, or any associated disorders. The marked diminution of in vitro T-cell reactivity noted for these later four patients was not due to a deletion of antigen- or mitogen-reactive cells. Thus, patients' cells which had been initially cultured for 7 days without any mitogenic or antigenic stimulus and which were subsequently washed and recultured with phytohemagglutinin, concanavalin A, or histoplasmin demonstrated a marked increase in their responsiveness. Moreover, this reactivity noted for recultured cells could be suppressed by a nonphagocytic, nonadherent, nonimmunoglobulin-bearing, sheep red blood cell rosette-forming population of cells isolated from the fresh peripheral blood mononuclear cells of the same patient. While these "regulator" T cells were capable of suppressing T-proliferative responses to antigens and mitogens, they did not diminish pokeweed mitogen-induced immunoglobulin synthesis by normal bone marrow-derived lymphocytes. Patients in whom suppressor "T" cells were found were at risk for relapsing, disseminated fungal infection.

Cell surface antigens of human malignant melanoma. II. Serological typing with immune adherence assays and definition of two new surface antigens.

Abstract: Immune adherence assays revealed that 10 out of 18 melanoma patients had demonstrable antibody to surface antigens of autologous cultured melanoma cells, with serum titers ranging from 1/4 to 1/160. Autologous fibroblasts showed no reactions with these sera. Antibody from individual patients showed reproducible temperature preference for maximal reactivity. Two new melanoma antigenic systems were defined in this study. The first, BD, was restricted to autologous melanoma and could not be demonstrated in absorption tests on 12 allogeneic melanoma cell lines. The other, AH, was found on 5 of 12 melanomas and represents a class of shared melanoma surface antigens. Neither BD nor AH antigen was found on normal cells from autologous, allogeneic, or xenogeneic sources or on any nonmelanoma tumor cell line. Methods are now available to develop a comprehensive serological classification of the surface antigens of melanoma.

A Microtiter Solid-Phase Radioimmunoassay for Hepatitis a Antigen and Antibody

Abstract: A microtiter solid phase radioimmunoassy for hepatitis A antigen (HA Ag) and antibody (anti-HA) was developed. The test was more sensitive than immune adherence hemagglutination for detecting HA Ag and almost as sensitive for detecting anti-HA. The specificity and sensitivity of reagents were examined and optimum conditions for the test were determined. Radioimmunoassay, immune adherence hemagglutination, and immune electron microscopy were compared for detecting anti-HA. A serologic response to HA Ag was detected in paired sera from patients with type A hepatitis but not from patients with type B or non-A, non-B hepatitis by all three techniques.

Autoregulation of simian virus 40 gene A by T antigen.

Abstract: During lytic infection by simian virus 40, gene A is transcribed into early RNA, which is translated into A protein (T antigen). Both the rate of synthesis and the intracellular amount of early RNA are higher in cells infected by temperature-sensitive A (tsA) mutants than in cells infected by wild-type virus. These differences are observed at permissive temperature (32 degrees) and are amplified greatly after a shift to restrictive temperature (41 degrees). For example, at 32 degrees cells infected by tsA mutants synthesize early RNA approximately twice as fast as cells infected by wild-type virus. After the shift to 41 degrees, the rate of synthesis in the tsA infection increases to 15 times the rate in the wild-type infection. In contrast, cells infected by tsA mutants do not overproduce late RNA. We suggest that the A protein regulates its own synthesis by negative feedback control of gene A transcription.