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Query: HUMANGGP:008557 (lectin)
 28,714 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human mononuclear phagocytes cultured in vitro revealed an inhibitory influence on DNA synthesis, as measured by 3H thymidine incorporation, in lymphocytes stimulated by a lectin (PHA), a soluble antigen (PPD) and allogenic lymphocytes. The inhibitory effect increased with increasing ratio of macrophages to lymphocytes, and was positively related to the differentiation of monocytes to macrophages. The inhibitory ability appeared to have no connection with the histocompatibility gene complex. The culture medium of macrophages cultured with and without lymphocytes showed no inhibitory effect.
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PMID:Inhibitory effect of human mononuclear phagocytes on DNA synthesis in stimulated lymphocytes. 14 9

DNA-synthesis, as measured by 3H thymidine incorporation, in immune lymphocytes from human blood stimulated in vitro with PPD was shown to require monocytes. No such requirement was demonstrated for PHA-induced DNA-synthesis under the same conditions. Initial packing of cells by centrifugation was beneficial for the cultures stimulated by antigen, but not for the cultures stimulated by lectin, thus indicating the necessity for contact between monocytes and lymphocytes for antigen stimulation. Monocytes and macrophages preincubated with PPD indced DNA-synthesis in lymphocytes. Monocytes were found to be least as capable of retaining and presenting antigen as macrophages, and autologous macrophages presented antigen more efficiently than allogeneic macrophages. DNA-synthesis in lymphocytes, induced by adding PPD or PHA to the culture medium, was inhibited by a large number of monocytes. Macrophages caused inhibition under the same conditions, even a small number. DNA-synthesis in lymphocytes induced by PPD-preincubated monocytes and macrophages increased with increasing ratio of mononuclear phagocytes to lymphocytes up to a certain value. A further increase in the ratio caused inhibition, thus indicating both an immunoinductive and an immuno-suppressive influence of mononuclear phagocytes.
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PMID:Immuno-inductive and immuno-suppressive influence of human mononuclear phagocytes cultured in vitro. 14 10

Data presented here on the quantitative 3H-thymidine incorporation into DNA, after PHA mitogenic stimulation, show that 21-trisomic lymphocytes are low-responders to PHA compared with the normal-diploid ones. Their responsiveness seems to decrease with the donor's age. Auto-radiographic studies clearly demonstrate that the fraction of labeled cells at the 72nd h of incubation is significantly smaller in the 21-trisomic lymphocyte population. The comparison of labeling indexes at different times of incubation (24, 48, 72 h) also indicate, in the same population, a slower increment of the portion of DNA-synthesizing cells. Discussing these data in the light of other's observations and recent progress in the knowledge of factors and mechanisms involved in the lymphocyte response to lectin mitogenic stimulus, it is suggested that differential distribution of T- and B- and/or T-cell subpopulations and a retarded cell induction time to proliferate may be two important factors negatively influencing the responsiveness of 21-trisomic lymphocyte population.
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PMID:Kinetics of 21-trisomic lymphocytes. I. In vitro response of 21-trisomic lymphocytes to PHA. 14 52

It has been demonstrated immunohistologically using cryostat sections that the lectins PHA and Con A bind to human placentae. Both lectins stain trophoblastic basement membrane (TBM), perivascular tissue and stroma. No staining of trophoblasts was observed. It has been shown by blocking experiments that the lectin binding sites on placental TBM are glycoproteins, whereas experiments involving pretreatment of placental sections with anti-collagen antisera or highly purified bacterial collagenase have indicated that lectin binding to stromal and perivascular structures is collagen-associated. The possible relation of TBM lectin-binding sites to immune response gene products is briefly discussed.
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PMID:Immunological studies of human placentae. Lectin binding to villous stroma and to trophoblastic basement membrane. 18 Nov 90

Short term effects (1 hours or less) of various lectins on phospholipid turnover in human lymphocytes were studied. As expected, concanvalin A and phytohemagglutinin produced 1,5-4.0 fold increases in incorporation of 32PO4 radioactivity into phospholipids (primarily phosphatidylinositol). Wheat germ agglutinin, a nonmitogenic lectin, not only failed to produce a response but actually inhibited phospholipid turnover, both in the presence and absence of PHA or con A. Since wheat germ agglutinin did not appear to be cytotoxic, as defined by a failure to see changes in vital dye uptake, and other evidence from our laboratory indicates that this lectin also inhibits aminisobutyric acid transport and DNA synthesis in human lymphocytes we would tentatively interpret its negative action as indicating the existence of specific inhibitory domains on the cell surface.
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PMID:Suggestive evidence for both stimulatory and inhibitory domains on human lymphocytes, as indicated by phospholipid turnover studies with wheat germ agglutinin and other lectins. 18 19

The immunoregulatory properties of LDL-In, a normal species of human serum low density lipoprotein which suppresses indictive events involved in triggering of lymphoid cells by lectins and antigens, were analyzed in order to distinguish between a primary effect on macrophages and lymphocytes. LDL-In was found to be equally effective in suppression of the response of human lymphocytes to tpha at concentrations of lectin demonstrated to impart apparent macrophage-independence or macrophage-dependence to the culture system. Exposure of only the macrophages to LDL-In was shown to be without effect on subsequent in vitro lymphocyte responses to either PHA or allogeneic cells, whereas exposure of only the lymphocytes to LDL-In was fully effective. The cellular locus was further identified by demonstrating that the responder lymphocytes, but not the stimulator lymphocytes, were the target of the suppressive activity in mixed lymphocyte reactions. These data considered in conjunction with previous studies suggest that the primary untriggered lymphocyte is the most probable cellular target for the bioregulatory effects of LDL-In.
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PMID:Effect of LDL-In, a normal immunoregulatory human serum low density lipoprotein, on the interaction of macrophages with lymphocytes proliferating in response to mitogen and allogeneic stimulation. 19 90

Phytohaemagglutinin (PHA M and P forms), when added to L 929 cells previously treated by murine interferon, degrades the antiviral state and restores virus sensitivity in the cells. This degradation depends on the amount of the lectin, the contact period with the cell and the presence of PHA membrane receptors. The importance of membrane configuration not only in the induction but also in the maintenance of the antiviral state is discussed.
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PMID:[Degradation by phytohemagglutinin of the antiviral state induced by interferon]. 19 19

1. Effects of concanavalin A (Con A) and other lectins on 5-hydroxytryptamine (5-HT) uptake by rabbit blood platelets and on their ultrastructure were studied. 2. Uptake of [3H]-5-HT by platelets was decreased by application of Con A, E-PHA (lectin from Phaseolus vulgaris) and lentil-PHA (lectin from Lens culinaris), but not by wheat germ agglutinin (WGA). Con A induced specific changes in the ultrastructure of platelets, causing (i) a change in external appearance from a discoid to an irregularly spherical shape, (ii) re-arrangement of the canalicular system and formation of a concentric structure. These effects of Con A on platelets were antagonized by pretreatment with alpha-methyl-D-mannoside (alpha-MM), a specific inhibitor of Con A binding to glycoprotein. 3. The inhibition of 5-HT uptake by Con A was antagonized by colchicine, vinblastine and sodium nitroprusside (SNP), but not by cytochalasin B. 4. Theophylline, papaverine and dibutyryl cyclic adenosine 3',5'-monophosphate (db cyclic AMP) antagonized the effect of Con A on 5-HT uptake, but dibutyryl cyclic guanosine 3',5'-monophosphate had no effect. Theophylline and db cyclic AMP did not influence the effect of Con A on the ultrastructure of platelets. 5. It is suggested that binding of Con A to specific receptor glycoproteins can inhibit the 5-HT uptake system of platelets. Microtubules, contractile protein and the membrane adenylate cyclase system of platelets may also be regulatory factors in this mechanism.
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PMID:Effects of concanavalin A on 5-hydroxytryptamine uptake by rabbit blood platelets and on their ultrastructure. 21 26

Normal human T cells grown in continued cultures in medium containing conditioned medium (CM) from PHA-stimulated lymphocytes were studied for their ability to manifest three known forms of cell-mediated cytotoxicity: lectin-induced cellular cytotoxicity (LICC), natural killer cell (NK) activity, and antibody-dependent cellular cytotoxicity (ADCC). The cultured T cells (CTC) were very effective mediators of LICC, being cytotoxic even at very low attacker-target cell ratios in the presence of different lectins, and against different types of targets. When tested without the addition of lectin, the CTC demonstrated a low degree of spontaneous cytotoxicity. This spontaneous cytotoxicity might not be due to conventional NK cells however, since the CTC failed to show significant numbers of cells with Fc receptors (FcR) for IgG, and had no detectable ADCC activity. CTC could represent a population enriched in polyclonal activated T cells with low spontaneous cytotoxicity against a variety of allogeneic target cells, which is greatly enhanced by the addition of lectins dur ing the 51Cr release assay.
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PMID:Cytotoxic activities of normal cultured human T cells. 30 61

The effect of fatty acids and other lipids on mitogenic responses in cultured human peripheral blood lymphocytes was studied. Several-fold enhancement of tritiated thymidine incorporation was observed at 0.1 to 5.0 micrograms/ml concentrations of arachidonic acid. Other unsaturated fatty acids produced less marked changes. Increased responsiveness was demonstrable in a variety of media including RPMI 1640 supplemented with 10% fetal calf serum. Changes were also observed in uridine incorporation, total cell number, and blast transformation, indicating that the effect was not on thymidine transport or pool size per se. Arachidonic acid failed to affect PHA binding, indicating that the lectin-cell interaction was not altered. Higher concentrations of fatty acids were inhibitory.
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PMID:Effects of arachidonic acid and other unsaturated fatty acids on mitogenesis in human lymphocytes. 44 98


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