Activation of T and B lymphocytes by insoluble phytomitogens

Hemagglutinin and neuraminidase specific cell-mediated immune responses to influenza A virus following immunization in guinea pigs

Groups of guinea pigs were immunized with different inactivated recombinant influenza A viruses including H3ChN2Ch, Heq1N2Ch, H3ChNeq1 or uninfected allantoic fluid. Employing hemagglutination and neuraminidase inhibition tests, an in-vitro lymphocyte transformation (LTF) assay, and rosetting techniques for the separation of lymphocytes, influenza hemagglutinin (HA) and neuraminidase (NA) specific antibody and cell-mediated immune (CMI) responses were evaluated. Inactivated H3ChN2Ch, H3ChNeq1, HavN2Ch, and Heq1Neq1 recombinant influenza viruses were used as test antigens. Following immunization the CMI and antibody responses to influenza were characterized by the induction of specific LTF and antibody activity to homotypic HA or NA antigens but not to heterotypic HA or NA antigens. The temporal kinetics of the antibody response to influenza antigens was characterized by a prompt onset being initially detected at 1-2 weeks and reaching peak titers 3-4 weeks after immunization. Influenza specific LTF responses were first detected one week after immunization and declined to minimal responses at eight weeks. T-lymphocytes but not B-lymphocytes were capable of in-vitro recognition of the HA and NA antigens. After recognition the subsequent in-vitro lymphoproliferation was shown to involve both T and B lymphocytes.

The binding of lectins to components of plasma membranes from porcine submaxillary lymph node lymphocytes

By sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis the plasma membranes from porcine lymphocytes contain at least 30--35 glycopolypeptides and one or more glycolipids to which one or more of 12 purified lectins bind. The specificities of binding generally followed the same pattern as those of the reaction of the lectin with intact pig lymphocytes. Some lectins (e.g., the isolectin pair, Agaricus bisporus lectins A and B and a group consisting of the Lens culinaris A and B isolectins and the closely related Pisum sativum lectins) bind to almost identical populations of plasma membrane components and compete with each other for all their binding sites. Others (e.g., Concanavalin A and the Lens culinaris-Pisum sativum group and a group consisting of phytohemagglutinin-L, Ricinus communis lectin-60 and Ricinus communis lectin-120 bind in a cross reactive manner to some common binding moieties but, in addition, to certain nonshared ones. Still others (e.g., soybean agglutinin, peanut agglutinin and wheat germ agglutinin) do not share any common binding moieties with the other lectins. The amount of lectin binding and the number of membrane components to which a lectin binds is directly related to the Ka of binding of the lectin to the intact lymphocyte. Those with high Ka (Cocanavalin A Lens culinaris lectins, Pisum sativum lectins, phytohemagglutinin-L), bind to 20-30 different components giving very complex binding patterns while those with lower Ka (Agaricus bisporus lectins, wheat germ agglutinin, peanut agglutinin, and soybean agglutinin) bind to 8--13 components with easily distinguishable patterns. Soybean agglutinin binds almost exclusively to a glycolipid fraction while for the others one or more glycopolypeptides served as the major lectin-binding molecule. The Ricinus lectins, two lymphocyte toxins, bind to essentially every plasma membrane component to which the mitogen phytohemagglutinin-L binds, in fact competing for most of those plasma membrane moieties which bind phytohemagglutinin-L.

Cell surface action of thrombin is sufficient to initiate division of chick cells

Thrombin covalently linked to carboxylate-modified polystyrene beads initiated division of quiescent chick embryo (CE) cells either in medium containing low levels of serum or in serum-free medium. Release of thrombin was monitored by measuring acid-precipitable radioactivity released from 125I-thrombin beads into the medium during incubation with cells. Even if all of the acid-precipitable material released from the beads were active thrombin, it was not sufficient to account for any of the observed cell division, and was 10-30 fold less than the amount necessary to produce the increase in cell number caused by the thrombin beads. Two other kinds of experiments also showed that material released into the medium did not account for the observed initiation of cell division. First, medium taken from cultures incubated with thrombin beads did not initiate cell division when added to new quiescent cultures. Second, in coverslip experiments where populations of cells with an without thrombin feads shared the same medium, only bead-contacted cells divided. Several results suggested that the material which was released from the thrombin beads resulted from cell-associated proteolysis rather than from "leakage" of intact thrombin from the beads. For example, after incubating 125I-thrombin beads with or without CE cells, we were unable to detect any intact thrombin released into the medium. In addition, most of the material released from the beads was acid-soluble and was only released in the presence of CE cells. A few thrombin beads were endocytosed by CE cells, but they were surrounded by an intact plasma membrane. Thus they did not directly interact with the cytoplasm. The close association of many of the beads with the cell surface and the presence of a few beads in endocytic vesicles made it important to consider the possibility that thrombin might be released from the beads directly into the cells. This possibility was explored using ultrastructural (EM) autoradiography. With this technique (where one grain represented 700--900 thrombin molecules), we found that beads inside the cells had approximately the same number of grains as beads not in contact with cells. This suggested that little, if any, additional radioactive material had been released from the beads which were in contact with the cells. In addition, we were unable to detect any grains in the cytoplasm which could be attributed to released thrombin, even using an amount of 125I-thrombin beads which was 8 fold greater than the amount which produced maximal cell division. Taken together, these results provide direct evidence that thrombin action at the cell surface is sufficient to initiate division of CE cells.

In vitro stimulation with mitogen and antigen in patients with monoclonal gammopathy

Peripheral blood lymphocytes from 32 patients with defined paraproteinaemia (16 IgG, 9 IgA and 7 IgM) and from 15 healthy donors were studied for their in vitro response to various stimuli, including for unspecific mitogens such as Phytohaemagglutinin (PHA), Pokeweed mitogen (PWM) and Concanavalin A (ConA) as well as specific antigens such as purified Tuberculin, Candida, Varidase, Tetanus Toxoid, Vaccinia antigen and Vaccinia-control antigen. Mitogens and antigens were lyophilized in Microtiter plates. The lymphocytes of all tested patient-groups responded (measured by H3-Thymidin-uptake) significantly lower towards the unspecific mitogens than those of the control group. If the patients' lymphocytes were stimulated by the specific antigens, their in vitro response was significantly diminished to candida and vaccinia. Macroglobulinaemia showed significantly lower response to ConA if compared to myelomas of IgG- and IgA-type. No correlation was found between mitogen and antigen response and the serum concentration of the paraproteins or immunoglobulins. The results show that monoclonal gammopathy and especially macroglobulinaemia are associated with abnormalities of the cellular immunity which correlates with the clinical observation of increased fungal and viral infections.

Transmembrane action of thrombin initiates chick cell division

Thrombin immobilized on polystyrene beads initiates DNA synthesis and cell division in quiescent cultures of chick embryo (CE) cells in serum-free medium. These thrombin beads also produce morphological changes in CE cells similar to those produced by soluble thrombin. The amount of acid-precipitable material released from 125I-thrombin-beads into the culture medium was 60-fold less than the amount of soluble thrombin required to produce an equivalent increase in cell number. Moreover, EM autoradiography of CE cells 10 h after 125I-thrombin-bead addition showed that there was no direct release and accumulation of radioactive material in the cytoplasm of these cells. These results demonstrate that thrombin action at the cell surface is sufficient to initiate proliferation of CE cells.

The effect of human spermatozoa on antigen and mitogen induced blastogenesis

In an attempt to identify factors capable of specifically or nonspecifically modulating results in an in vitro blastogenic assay system, studies were performed evaluating cell mediated immune response to human spermatozoa. Spermatozoa were capable, on a dose dependent basis, of both inhibiting and stimulating normal lymphocyte DNA synthesis as well as suppressing mitogen-induced response. Pretreatment of spermatozoa with neuraminidase and alpha-methyl-D-mannoside abrogated suppressive properties on spontaneous and/or mitogen-induced stimulation. Such suppressive activity on mitogen-induced response was observed using B and T-cell enriched populations. Inhibitory properties were not evident using intact cell populations stimulated by specific antigen. It is suggested that: (1) receptors on spermatozoa bind lectin; and (2) such receptors can be inactivated by enzymes having glycoprotein specificity.

Lipopolysaccharide effects on sensitive and resistant variant Chinese hamster ovary cell lines

Chinese hamster ovary (CHO . K1 . PRO) cell growth was inhibited by addition of a gram-negative bacterial lipopolysaccharide (LPS) to the cell culture medium. Growth inhibition began after three or four days of incubation, was dose-dependent up to a maximum at an LPS concentration of 500 microgram/ml and was accompanied by cell shape changes and enhanced cytoplasmic vacuolization. Formation of bizarre CHO . K1 . PRO cell shapes and vacuole formation were most pronounced after seven days of incubation with LPS and could be observed by light and electron microscopy. An LPS-resistant cell population was obtained by intermittent in vitro exposure to high levels of LPS; these variant cells or clones derived from them failed to display growth inhibition in the presence of LPS. A clone from the LPS-resistant variant population showed altered cell properties compared to the parental cell line which included changes in cell morphology, adhesion, and endocytosis. Parental cells was markedly density-inhibited, whereas the cariant clone exhibited considerable growth after confluency. The LPS-resistant variant cells showed a more elongated morphology than the parental line. No significant differences were observed between rates of detachment of parental and variant cells when sparse cultures of either line were removed from tissue culture dishes by ethylenediaminetetracetate (EDTA). However, at confluency approximately 100% of the variant cells versus 35% of the parental cells were removed by EDTA in one hour. Measurements of 125I-ferritin uptake by parental and variant cells showed approximately twenty-fold and twofold increases, respectively, in uptake induced by LPS when compared to untreated control cultures.

Initiation of check cell division by trypsin action at the cell surface

Trypsin immobilised on polystyrene beads causes initiation of cell division which cannot be accounted for by trypsin released into the medium or into the cells. Also, initiation by soluble trypsin is inhibited by immobilised soybean trypsin inhibitor. These results demonstrate that trypsin can initiate proliferation at the cell surface.

Down regulation in B lymphocytes: low dose signals

Picogram quantities of dinitrophenylated (DNP) dextran, a thymus-independent antigen or lipopolysaccharide, a B cell mitogen, signal down B lymphocytes to unresponsiveness. Down signals were detected by a decision test in which signaled lymphocytes were allowed one hour to react to an immunogenic pulse of DNP-dextran. Depletion of T cells or macrophages did not interfere with the generation of down signals. The signaling can proceed entirely at 4 degrees C and it its negative effect is transitory. Down signals which could be detected after 15 min at 37 degrees C were reversed by 60 min. It is suggested that down regulation by low dose antigenic signals provides a means of distinguishing background noise from true antigenic stimuli.

Serum albumin biosynthesis and secretion by resting and lectin stimulated human lymphocytes

Normal human peripheral lymphocytes, cultured in serum-deprived medium, synthetized and released serum albumin and some glycoproteins into the culture supernatant. With the use of [3H]leucine, it was shown that this biosynthetic activity was increased about 2-3 times when the mitogenic lectin from Robinia pseudo acacia was added to the lymphocyte culture medium.

Karyometric and cytophotometric studies on nucleic acids in the culture of human lymphocytes with phytohemagglutinin

Lymphocyte transformation with phytohemagglutinin (PHA) was analyzed by karyometry and cytophotometry of single cells. The former showed the distribution of various-sized transforming cells, and the latter the increase of DNA and RNA. Two different types of karyograms were obtained; one with three peaks corresponding to 2c, 4c, and 8c, and the other with only a 2c peak. Although small in number (8%), karyometry showed that DNA synthesis took place in the extremely early stage of transformation, 1 h after stimulation with PHA, which was proved by cytophotometry and ultrastructural findings. An increasing curve of DNA and RNA revealed that a lymphocyte continued to enlarge from 2c to 4c and divide again through the normal cell cycle in a suitable condition. The largest blast cell, a polyploid cell, may be induced by the lack of a sufficient amount of RNA and protein in need of cell division, and may be a degenerative cell in the strict sense. Among the large cells with blastlike appearance, there were a considerable number of so-called degenerative cells with a low amount of DNA. The ratio of RNA to DNA increased steeply in the actively DNA synthesizing S phase, which supports the morphologic findings of blast cell, the appearance of basophilic cytoplasm, and active-looking nucleoli.

Control of B-lymphocyte function. I. Inactivation of mitogenesis by interactions with surface immunoglobulin and Fc-receptor molecules

Mouse spleen cells were incubated with anti-Ig antibodies for 1 h, washed, exposed to LPS for 1 h, washed, and their DNA synthetic responses assayed 2 days later. It was shown that the 1-h incubation with anti-Ig antibodies produced a profound, internal, and long lasting state of inactivation in the B cells. Experiments with anti-Ig fragments and other ligands showed that the inactivation occurred optimally when both surface Ig molecules and Fc receptors were bound simultaneously. The role of the classical capping and clearing cycle was also investigated. It was shown that capping and clearing were neither necessary nor sufficient for the inactivation to occur, and that the signals, but only secondarily the ligands themselves, were transmitted across the membrane. Capping and clearing were viewed as a natural regulatory mechanism by which the B cell attempts to clear its membrane of perturbations and signals from the exterior.

Membrane pathology of normal and malignant cells--a review

The plasma membrane has been shown to play a critical role in the regulation of cell growth and proliferation, and pathologic change in the plasma membrane has been detected in neoplastic cells. This article reviews the structure and functions of biological membranes and discusses the differences that have been reported in the plasma membranes of normal and malignant cells that may be associated with neoplastic transformation.

Reactivity of lymphocytes from primary neoplasms of lymphoid tissues

Proliferative responses by blood and tumor lymphocytes to plant mitogens and allogeneic leukocyte antigens were tested concomitantly on 12 patients with Hodgkin's disease, 10 with chronic lymphocytic leukemia, and seven with non-Hodgkin's lymphomas. In 13 control studies, 3H-thymidine incorporation by blood and lymph node lymphocytes was brisk and, overall, comparable. With Hodgkin's disease, where extent of disease involvement and lymphocyte-depleted tumor histology were factors in the degree of responsiveness, incorporation was higher or at least comparable by tumor lymphocytes when compared with incorporation by autologous blood lymphocytes. Lymph node lymphocytes, especially with clinically stable disease, were more responsive than blood lymphocytes with chronic lymphocytic leukemia. Conversely, tumor lymphocytes were hyporesponsive compared with autologous blood lymphocytes with non-Hodgkin's lymphomas, where prognosis is usually less favorable than with chronic lymphocytic leukemia. Plasma from four out of 33 patients, although not lymphocytotoxic, inhibited lymphoproliferative responses.

Immunological characterization of lymphoproliferative disorders by membrane markers

The characterization of lymphocyte subpopulations by means of surface markers improved our understanding of the immunopathology of lymphoproliferative disorders. In chronic lymphocytic leukemia an accumulation of B-lymphocytes have been documented. The antibody deficiency syndrome in these patients might well reflect a maturation defect of the leukemic B-lymphocytes. In patients with Hodgkin's disease the relative number of B- and T-lymphocytes in the blood was not markedly altered in comparison to normal controls. An increased proliferation primarily of T-lymphocytes however, might suggest their accelerated turnover as an indication of the host response. In most patients with "Non-Hodgkin" lymphomas high numbers of B-lymphocytes were found in affected lymph nodes, and these appear occasionally in the peripheral blood. Differences in immunopathological manifestations of the various subgroups of the "Non-Hodgkin" lymphomas are emphasized and the rare occurrence of lymphomas of T-lymphocytes (mainly observed in lymphoblastic lymphomas and in Sézary syndrome) is discussed. Immunopathological alterations in immunocytomas and the myelomas are considered in respect to the involvement of B-lymphocytes at different stages of maturation.

Cooperative binding of concanavalin A to thymocytes at 4 degrees C and micro-redistribution of concanavalin A receptors

The mode of binding of 125I-labelled concanavalin A and succinyl-concanavalin A to rat thymocytes at 4 degrees C was investigated. Simultaneously, the free binding sites of the cell-bound lectin molecules were quantified by horseradish peroxidase binding. Concanavalin A showed cooperative binding while succinyl-concanavalin A did not. The number of molecules of concanavalin A bound to the cell surface when it was saturated was twice the number of molecules of succinyl-concanavalin A. We interpret these results as showing that the binding of native concanavalin A to thymocytes at 4 degrees C brings about a cooperative modification of the membrane which leads to appearance of new receptors. Divalent succinyl-concanavalin A has no such effect. Horseradish peroxidase binding to cell-bound lectin was shown to be related to the immobilization of membrane receptors; the more they are immobilized, the more receptor-associated lectin can bind horseradish peroxidase. This allowed us to establish that post-binding events, which we called micro-redistribution, occurred at 4 degrees C when either concanavalin A or succinyl-concanavalin A binds to cells. A cooperative restriction of the micromobility of cell receptors is produced by increasing concentrations of concanavalin A. Succinyl-concanavalin A does not restrict cell receptor mobility at any concentration tested. The results are discussed in terms of cell stimulation and cell agglutination.

T and B lymphocytes in non-Hodgkin's lymphoma: a comparison of tumor-derived cells and peripheral blood lymphocytes

T- and B-cell markers of lymphocytes in peripheral blood, involved node and spleen, PHA response of peripheral blood lymphocytes, serum immunoglobulin levels, and skin test reactivity to six common antigens were studied in 16 cases of untreated non-Hodgkin's lymphoma. Impaired response of peripheral lymphocytes to PHA was observed in 13 of 16 cases, regardless of the proportion of T lymphocytes. Of 12 cases in which skin tests were done, two were positive and had a normal PHA response, seven cases were positive in spite of low PHA response, and three were negative with low PHA response. In the lymph nodes from involved areas two cases showed monoclonal increase of B-cells, five showed "null" cell increase, and the remaining nine showed no increase or decrease of subpopulation of lymphocytes. No correlation with surface marker of lymphocytes to histologic classification was seen. From the above observations it was concluded: 1) a low PHA response in non-Hodgkin's lymphoma was not due to the decreased population of T-cells; 2) a low PHA response may not necessarily indicate impaired delayed hypersensitivity; and 3) non-Hodgkin's lymphoma can be classified in the following ways--B-cell proliferative type, "null" cell increase type, and normal T/B proportion type.

The subcellular distribution of adenylate and guanylate cyclases in murine lymphoid cells

Membrane vesicles can be prepared from murine lymphoid cells by nitrogen cavitation and fractionated by sedimentation through nonlinear sucrose density gradients. Two subpopulations of membrane vesicles, PMI and PMII, can be distinguished on the basis of sedimentation rate. The subcellular distribution of adenylate and guanylate cyclases in these membrane subpopulations have been compared with the distribution of a number of marker enzymes. Approximately 20-30% of the total adenylate and guanylate cyclase activity is located at the top of the sucrose gradient (soluble enzyme), the remainder of the activity being distributed in the PMI and PMII fractions (membrane-bound enzyme). More than 90% of the 5'-nucleotidase and NADH oxidase activities detected in lymphoid cell homogenates are located in PMI and PMII fractions, whereas succinate cytochrome c reductase activity is detected only in the PMII fractions. In addition, beta-galactosidase activity is distributed in the soluble and PMII fractions of the sucrose density gradients. On the basis of the fractionation patterns of these various enzyme activities, it appears that PMI fractions contain vesicles of plasma membrane and endoplasmic reticulum, whereas PMII fractions contain mitochondria, lysomes, and plasma membrane vesicles. Approximately 30-40% of the adenylate and guanylate cyclase activities in PMII can be converted to a PMI-like form following dialysis and resedimentation through a second nonlinear sucrose gradient. Adenylate and guanulate cyclases can be distinguished on the basis of sensitivity to nonionic detergents.

The requirement for tetravalency of soybean agglutinin for induction of mitogenic stimulation of lymphocytes

The mitogenic activity of soybean agglutinin was found to depend on the presence of lectin aggregates formed in lectin preparations stored in the lyophilized state. Such soybean agglutinin preparations gave maximal stimulation of untreated pig lymph node cells and neuraminidase-treated mouse spleen cells at relatively high concentrations, ranging from 100 to 2000 mug/ml. After separation into unaggregated (divalent) and polymeric (tetra-and multivalent) fractions, it was found that the unaggregated lectin did not stimulate the cells, while the tetravalent and multivalent fractions were active and gave maximal stimulation at a concentration of 10 mug/ml. These results suggest that soybean agglutinin must have at least four sugar binding sites in order to be able to stimulate lymphocytes.

Lymphocyte activation. VIII. The application of a whole blood test to the quantitative analysis of PHA responsive T cells

In diluted blood predominantly T cells responded to purified PHA (pure leucoagglutinin Wellcome). Red cells and non-T mononuclear cells increased PHA responsiveness of T cells at concentrations present in the peripheral blood. Addition of polymorphonuclear leucocytes was a very slight further advantage. The incorporation of [3H] thymidine reflected the numbers of T cells in culture, although not perfectly linearly, since counts increased when more T cells were added to the cultures. It was therefore concluded that in cultures of diluted whole blood non-specific amplification mechanisms were provided and responses reflected the performance of stimulated T lymphocytes. Since the method is simple and the number of technical variables is relatively small, it is possible to establish a "normal" range of PHA responsiveness expressed in absolute counts per minute, and thus directly compare results from different laboratories.

Inhibition of B lymphocyte activation by interaction with Fc receptors

Much early work indicated that specific antibody can play an inhibitory role in the immune response. This inhibitory activity was found to be dependent on an intact Fc portion of the antibody used, both in vivo and in vitro. Thus a role for lymphocyte Fc receptors in regulations of the immune response was suggested. However, soluble antigen-antibody complexes, which bind to Fc receptors, do not appear to inhibit B cell activation. Recent experiments have demonstrated that antigen-antibody complexes immobilized on a surface strikingly inhibit LPS induced B cell mitogenesis and polyclonal antibody synthesis. Mechanisms for Fc receptor-mediated inhibition of B cell activation have been considered, and a model proposed to explain many of these findings as well as allow for antigen specific inhibition.

Post recognition ion dependent events in mitogen induced lymphocyte proliferation and in cytotoxic effector cell responses

This review discusses the increased permeability and enhanced uptake transport of monovalent and divalent cations following mitogen-induced lymphocyte proliferation. The observed Ca2+ uptake is discussed in terms of gated Ca2+ channels. The importance of divalent cations, particularly Ca2+, is discussed in terms of triggering of cytotoxic effector cell responses for three model systems (antibody dependent cytotoxicity, mitogen-induced cytotoxicity and cell mediated cytotoxicity); (85).