Interleukin 1-Induced Down-Regulation of Antibody Binding to CD4 Molecules on Human Lymphocytes

Interleukin 1 (IL-1) is involved in the early activation of T lymphocytes. The CD4 antigen, described as a phenotypic marker of helper T cells, is also important in early T-cell activation by its ability to bind to MHC class II molecules on antigen-presenting cells, and to transmit positive (and negative) signals to the cells. We observed that purified human monocyte IL-1 as well as recombinant IL-1 alpha and IL-1 beta selectively decreased the binding of monoclonal antibodies to CD4 on the surface of otherwise unstimulated blood T cells, in contrast to prestimulated and continuously grown CD4+ cells. Under optimal growth conditions, the initial reduction in antibody binding to CD4 was followed by an apparent re-expression of the CD4 antigen even in the presence of high concentrations of IL-1. This re-expression did not occur if the cells were cultured at 4 degrees C, or after treatment with actinomycin D or cytochalasin B, indicating that protein synthesis and intact microfilament function were essential for re-expression of CD4 binding. The mechanism by which CD4 molecules are physically and/or functionally modulated by IL-1 is unclear.     

SEB活化的人外周血T细胞CD25,CD69的表达

本文用超抗原葡萄球菌肠毒素B(SEB)诱导外周血淋巴细胞增殖。结果显示出微量超抗原能诱导外周血淋巴细胞的增殖,大量的增殖反应发生在SEB刺激后的第5天,增殖的细胞是CD4~+T细胞,它们由刺激前的27％增加到42％。外周血活化的T细胞不依赖外源性IL-2:大量内源性IL-2的存在抑制T细胞的增殖反应。伴随CD4~+T细胞的增殖,CD25和CD69分子表达明显增加。提示SEB能改变外周血T细胞表面的分子表达。     

Expression of CD40 and CD43 during Activation of Human B Lymphocytes

CD40 and CD43 are two cell-surface glycoproteins that appear to be functionally involved in the growth stimulation of human B cells. Whereas CD40 is structurally similar to the NGF receptor and is present on all resting B cells, CD43 displays no homology to other known proteins and is expressed only on a subpopulation of these cells. To further understand the extra- and intracellular signals regulating these molecules and in which stage of activation they may play a role, we used various activation strategies and studied their expression on tonsillar B cells. As expected, activation of protein kinase C by TPA increased both CD40 and CD43. In contrast, a rise in intracellular Ca2+, e.g. by ionomycin, did not influence the expression of these antigens. However, in the presence of TPA, ionomycin further up-regulated CD43 but not CD40. Anti-IgM behaved similarly to ionomycin suggesting that the effect of this reagent was due primarily to its ability to increase intracellular Ca2+. Of three interleukins (IL-2, IL-4 and IL-6) only IL-4 had a significant effect when used alone in that it up-regulated CD40 but not CD43. However, in the presence of anti-IgM, both IL-2 and IL-4 synergistically up-regulated the two antigens. Complementation of antigen receptor stimulation with TPA or IL-4 increased CD40 during the first 24 h, whereas up-regulation of CD43 did not occur until 24 to 48 h after stimulation. With regard both to up-regulation in response to different stimuli and to kinetics, CD40 expression paralleled that of the early activation antigen CD23, whereas CD43 was induced in parallel with the transferrin receptor (CD71). Taken together, our results suggests that the expression of CD40 and CD43 is regulated by different intracellular signals and that CD40 may be important during early activation, whereas CD43 may have its major function during later stages of B-cell differentiation. These assumptions are in line with the observations that CD40 antibodies can directly activate resting B cells and that CD43 are retained on plasma cells.     

Down-Regulation of CD59 (Protectin) Expression on Human Colorectal Adenocarcinoma Cell Lines by Levamisole

The vulnerability of tumour cells to complement-mediated immune attack is regulated by membrane associated molecules. Recently, we have shown that the expression of the membrane attack complex inhibitor CD59 is enhanced on colonic adenocarcinoma cells compared to normal colonic epithelial cells. CD59 was shown, in the same study, to protect the tumour cells from complement-mediated lysis. Levamisole (LMS), used in conjunction with 5-fluorouracil as adjuvant therapy, reduces the incidence of colon cancer relapse following surgical resection. This led to our investigation of the effect of LMS on CD59 expression and function on the human colorectal cell lines HT29 and Caco-2. When cultured in the presence of 10 μM LMS, the cells reduced their expression of CD59 in a time-dependent manner. LMS treated HT29 ceils were more sensitive to lysis by complement than control cells, and the reduction in CD59 expression was shown to be partly responsible for this. A reduction in CD59 expression will augment complement-mediated immune surveillance and may contribute to LMSs anti-tumour activity in vivo .     

Sustained CD28 Expression Delays Multiple Features of Replicative Senescence in Human CD8 T Lymphocytes

CD28 costimulatory signal transduction in T lymphocytes is essential for optimal telomerase activity, stabilization of cytokine mRNAs, and glucose metabolism. During aging and chronic infection with HIV-1, there are increased proportions of CD8 T lymphocytes that lack CD28 expression and show additional features of replicative senescence. Moreover, the abundance of these cells correlates with decreased vaccine responsiveness, early mortality in the very old, and accelerated HIV disease progression. Here, we show that sustained expression of CD28, via gene transduction, retards the process of replicative senescence, as evidenced by enhanced telomerase activity, increased overall proliferative potential, and reduced secretion of pro-inflammatory cytokines. Nevertheless, the transduced cultures eventually do reach senescence, which is associated with increased CTLA-4 gene expression and a loss of CD28 cell surface expression. These findings further elucidate the central role of CD28 in the replicative senescence program, and may ultimately lead to novel therapies for diseases associated with replicative senescence.     

Increased Expression of CD25 and HLA-DR on Lymphocytes Recruited into the Peritoneal Cavity in Non-Infected CAPD Patients

The impact of uremia per se, peritoneal dialysis (PD) and hemodialysis (HD) treatment was evaluated on characteristics of lymphocytes. CD4, CD8, CD25 and HLA-DR were analyzed, with flow cytometry, in lymphocytes prepared from peripheral blood of uremic (n = 10) and hemodialysis patients (n = 10). Peritoneal dialysate was also obtained from patients on CAPD (n = 12). A decreased relative and absolute lymphocyte count was observed in peripheral blood from uremic, HD and CAPD patients compared to healthy controls (p < 0.03, p < 0.03 and p < 0.02, respectively). On the other hand, the relative distribution of lymphocytes was significantly higher in peritoneal dialysate compared to peripheral blood of CAPD patients (p < 0.02). Likewise, the absolute CD4 positive lymphocyte count was lower in the peripheral blood from uremic, HD and CAPD patients as compared to healthy controls (p < 0.001, respectively). In CAPD patients the relative distribution of CD4 positive cells (p < 0.001) was lower, while quantitative CD25 level (p < 0.01) and the relative count of HLA-DR (p < 0.0001) was increased in the peritoneal dialysate compared to blood. Taken together a selective activation of lymphocytes in peritoneal dialysate as compared to peripheral blood from uremic, HD and CAPD patients was observed. The altered biological function of the inflammatory cells may therefore explain the increased susceptibility to infectious diseases.     

Family of Large Surface Proteins on Human Lymphocytes

Cells surface molecules of T-rosette-positive human peripheral blood lymphocytes were labelled by lactoperoxidase and examined on 5% polyacrylamide gels. Several bands, ranging in molecular weight from 220,000 to 170,000 daltons, were seen. Analysis of the tryptic and chymotryptic digests of the 187K. 200K, 210K and 220K proteins indicated that they are of similar peptide composition. Study of clones derived from this population indicated that individual cells within a population differed in expression of these proteins.     

Expression of Adhesion Molecules and CD28 on T Lymphocytes during Human Immunodeficiency Virus Infection

Adhesion molecules, which play a major role in lymphocyte circulation, have not been well characterized in human immunodeficiency virus (HIV) infection. T-lymphocyte populations, including CD3, CD4, CD28, and adhesion molecules (L selectin, LFA-1, VLA-4, and ICAM-1) were measured by flow cytometry in a cross-sectional study of 100 HIV-infected and 49 HIV-seronegative adults. HIV-infected adults had lower numbers of CD3⁺ lymphocytes expressing L selectin (P < 0.0001) and VLA-4 (P < 0.01) and higher numbers of CD3⁺ lymphocytes expressing LFA-1^bright (P < 0.002) than did HIV-negative adults. By CD4⁺-lymphocyte count category (>500, 200 to 500, or <200 cells/μl), HIV-infected adults with more advanced disease had lower percentages of CD3⁺ lymphocytes expressing L selectin and VLA-4 and higher percentages of CD3⁺ lymphocytes expressing LFA-1. The percentages of CD3⁺ CD28⁺ lymphocytes and of CD3⁺ L selectin⁺ lymphocytes were positively correlated (Spearman coefficient = 0.86; P < 0.0001), and the percentage of CD3⁺ CD28⁺ lymphocytes and the CD3⁺ LFA-1^bright lymphocyte/CD3⁺ LFA-1^dim lymphocyte ratio were negatively correlated (Spearman coefficient = −0.92; P <0.00001). The results of this study suggest that HIV infection is associated with altered expression of adhesion molecules.     

Surface Markers on Human B and T Lymphocytes

An association has been found between the Epstein-Barr virus (EBV) and complement (C3d) receptors on human lymphoid cells. The evidence was four-fold: there was a correlation between the expression of these two receptors; inhibition experiments showed that the binding sites probably are close to each other in the cell membrane, although not identical; EBV and complement receptors have been found to co-cap in either order; and lymphoid cell lines lacking complement receptors could not be superinfected with EBV.     

Surface Markers on Human B and T Lymphocytes

The response of human peripheral lymphocytes to phytohemagglutinin-. concanavalin A-, pokeweed mitogen-, and mitomycin-treated allogeneic lymphocytes was characterized according to the surface markers of the responding cells Almost all blast cells derived from these cultures could be classified as either B or T cells Phytohemagglutinin, concanavalin A, and allogeneic lymphocytes triggered exclusively T-tell stimulation, whereas pokeweed mitogen gave rise to a dual response. No shift in the proportion of responding B and T cells was found If different concentrations of pokeweed mitogen under the present conditions Purified T cells, isolated by sheep erythrocyte (SRBC) rosette sedimentation, responded slightly more strongly than unseparated cells, whereas purified non-SRBC-binding; cells were essentially unresponsive to all three lectins. The presence of monocytes was found to increase the lectin responses as well as to make them more re producible. It is suggested that the classification of proliferating lymphocytes by surface markers may yield clinical information as well as serve as a useful tool in the evaluation of in vitro cellular cooperation     

Surface Markers on Human B and T Lymphocytes

The distribution of surface immunoglobulin and receptors for Fc, C3, and sheep erythrocytes (SRBC) on resting and blast-transformed peripheral lymphocytes was investigated. The following conclusions were reached. [1] SRBC receptors were retained on all blast-transformed T lymphocytes. No such receptors were found on normal or neuraminidase-treated B lymphocytes. [2] Receptors for Fc and C3 were found to be expressed on the same resting lymphocytes, which formed a subpopulation that did not entirely overlap with surface immunoglobulin-positive B cells. Owing to this and the fact that Fc/C3 receptors were lacking on almost all B blast cells, as well as for other reasons elaborated in the text, it is argued that caution must be taken when these receptors are used as B-cell markers. [3] A comparison among C3 indicator cells prepared with human or mouse complement showed that these detected the same lymphocyte subpopulatiom [4] B blast cells, induced by 72-hr pokeweed mitogen cultures, were found to carry detectable amounts of surface immunoglobulin. [5] Phagocytic leukocytes were found to be conveniently detected by scoring the number of cells with internal C3 indicator cells after osmotic lysis of externally bound indicator cells.     

Surface Markers on Human B and T Lymphocytes

Almost 100% of peripheral T lymphocytes are shown to have the capacity to form rosettes with human lymphoblastoid B-cell lines, predominantly at 4°C and with lines having surface-bound IgG. Blast-transformed T cells retained this capacity and formed rosettes even at 37°C Unstimulated T cells bound less readily to B-cell blasts, stimulated by pokeweed mitogen for 72 hr. Even though rosettes, formed at 4°C, were stable for several hours at 72°C, no T-cell-mediated cytotoxicity could be detected during overnight incubation. Extreme pH values and trypsinization decreased rosette formation, whereas neuraminidase treatment enhanced the reaction. Rosette formation was independent of bivalent cations and unimpaired in the presence of inhibitors (NaF. NaN₃), undiluted human or fetal call sera, protein A, sonicated sheep erythrocyte membranes, and normal or heat-aggregated human IgG. Anti-Ig, anti β₂-microglobulin, or anti-T cell sera did not influence rosette formation.     

Differentiation of T Lymphocytes in the Human Adenoid as Measured by the Expression of CD45 Isoforms

Encounter of antigen by T lymphocyte on antigen-presenting cells results in changes in the expression of several cell surface molecules, including the abundant cell surface glycoprotein CD45. We have characterized the expression of the CD45 isoforms CD45RA and CD45RO in CD4⁺ and CD8⁺ T lymphocytes in the adenoids and peripheral blood of young children. We found that the relative proportions of CD45RA⁻,CD45RO⁺ antigen-experienced T cells was higher in the adenoids than in peripheral blood, and that the proportion of naive or resting CD45RA⁺,CD45RO⁻ T cells was lower in the adenoids than in peripheral blood. The frequency of bright double-positive CD45RA⁺,CD45RO⁺ T cells, which represent cells in transition from the CD45RA⁺ to CD45RO⁺ phenotype, was higher in the adenoids than in peripheral blood. The frequency of another double-positive cell population, but with unknown ontogeny, expressing both CD45RA and CD45RO at a low level, was higher in peripheral blood than in adenoidal T cells. It was found that the frequency of adenoidal antigen-experienced CD45RA⁻,CD45RO⁺ T lymphocytes increased with increasing age of the child. These results are consistent with the model that the adenoids serve as a site for conversion of CD45RA⁺ to CD45RO⁺ T lymphocytes, and that the maturation of the immune system in young children is associated with phenotypic changes in T lymphocytes residing in secondary lymphoid organs.     

Surface Markers on Human B and T Lymphocytes

A procedure to assess the cellular adherence displayed by lymphocytes, at the level of the single cell, is described. Adherence is defined as the capacity of a cell to hind acrylic acid polymer beads. 0.5 μm: in size, under standardized conditions These beads were found to adhere readily to lymphocytes that have a high density of surface immunoglobulin Such cells can be distinguished from other leukocytes with the same binding capacity by the extracellular localization of the beads on these cells Furthermore, adherence, as presently defined, is briefly characterized.     

Expression of Human Placental Cell Surface Antigens on Peripheral Blood Lymphocytes and Lymphoblastoid Cell Lines

The expression of human placental cell surface antigens was examined in cells of lymphoid origin, including peripheral blood lymphocytes and cultured lymphoblastoid cells of bone marrow or thymus derivation. A select group of this. defined set of surface antigens was detected on all three cell preparations. The most remarkable observation was the conspicuous absence of three subunits previously demonstrated to be present on all human cell surfaces examined to date. Antiserum directed against several placental components prevents adhesion and spreading of cell which grow attached to surfaces. These results suggest a role for these three glycoproteins in mediating cellular adhesion.     

Changes in the Expression of Ig-Associated Proteins on B Lymphocytes Activated by Anti-IgM Antibodies

Binding of antigen to receptor complexes on B cells elicits a cascade of intracellular signalling events leading to proliferation and. together with T-cell help, Ig secretion. Components of the antigen receptor (AgR) complex have been demonstrated to be either covalenlly bound or associated with surface Ig (sIg) molecules. The function of these proteins is still unknown. In order to address this question, we have stimulated B cells with anti-μ antibodies and have studied possible changes in the expression of AgR complexes. After anti-μ stimulation, the IgM molecules disappeared rapidly from the cell surface together with the covalently bound proteins. The IgM molecules were internalized and probably degraded. The IgM-associated heterodimer Ig-α/Ig-β was also removed from the cells, leaving the IgD-associated heterodimer unaffected. Two proteins showed an enhanced association with slg after 15 min and then were gradually removed from the cell surface. Two other proteins became increasingly attached to sIg. This association remained stable for the rest of the culture period (up to 4 h). Further studies are underway to characterize these proteins more closely and to examine possible interactions with downstream members of the signalling cascade.     

Expression of Inhibitory Receptors in Natural Killer (CD3CD56) Cells and CD3CD56 Cells in the Peripheral Blood Lymphocytes and Tumor Infiltrating Lymphocytes in Patients with Primary Hepatocellular Carcinoma

The cytolytic responses of NK (CD3(-)CD56(+)) and CD3(+)CD56(+) cells are inhibited by the engagement of the killer inhibitory receptors (p58.1, p58.2, and CD94) with respective ligands on the target cell. The expression of these receptors in peripheral blood lymphocytes (PBLs) (n = 18) and tumor infiltrating lymphocytes (TILs) (n = 7) was examined in patients with primary hepatocellular carcinoma (HCC). There were no differences in the expression of the three inhibitory receptors by both NK and CD3(+)CD56(+) PBLs in patients with HCC compared to that of control NK and CD3(+)CD56(+) PBLs, respectively (all P = NS). However, the expression of p58.1 by NK TILs and by CD3(+)CD56(+) TILs in patients with HCC was significantly decreased compared to that of hepatic lymphocytes of the control subjects (8.9% vs 37.85%, P = 0.047; 4.1% vs 25.2%, P = 0.049, respectively). The expression of p58.2 by CD3(+)CD56(+) TILs and CD94 by NK TILs was also decreased compared to that of hepatic lymphocytes of the control subjects (16.9% vs 73.1%, P = 0.047; 21% vs 49.95%, P = 0.037, respectively). These changes were limited to hepatic TILs, and this observation may reflect an adaptive anti-tumor phenomenon occurring in the microenvironment of HCC.     

Concanavalin-A-binding Proteins on the Surface of Human Malignant and Normal Lymphocytes

The concanavalin-A-binding cell surface glycoproteins from normal and certain leukaemic human lymphocytes were radiolabelled and then solubilized with detergent, isolated by affinity chromatography on Con A insolubilized on agarose beads, and subsequently analysed by SDS-polyacrylamide gel electrophoresis. Leukaemic T cells from patients with Sezary syndrome were found to express major concanavalin-A-binding glycoproteins on their outer surface similar to those of normal T lymphocytes. Leukaemic B cells from patients with chronic lymphocytic leukaemia expressed Con-A-binding proteins similar to those of B-cell lines. HLA antigens were predominant among the major Con-A-binding proteins on the surface of the normal and the malignant T cells studied. Human Ia-like antigens, HLA antigens, and the cell surface immunoglobulins IgD and IgM represented the major Con-A-binding proteins on the B cells studied. beta 2-microglobulin was found associated with HLA antigens on both leukaemic and non-leukaemic T and B cells. The presence of additional Con-A-binding proteins expressed on the surface of the different cell types studied is discussed along with some physical characteristics of the human Ia-like antigens isolated.     

Expression of CD26 (Dipeptidyl Peptidase IV) on Resting and Activated Human T-Lymphocytes

CD26 is an activation antigen which is expressed on the surface of human T-lymphocytes. It has been characterized to be the dipeptidyl peptidase IV (DPP IV). Considerable amounts of CD26 are already present on resting T-lymphocytes. The expression of CD26 is enhanced by T-cell mitogens or antigens. A correlation of CD26 expression and of enhanced enzymatic activity was observed after T-cell activation. Our data indicate that not only the immunoreactivity, but also the enzymatic activity of CD26 are detectable on the cell surface. In addition, de novo expression of CD26 was demonstrated on CD26-negative T-cells after mitogenic or antigenic stimulation. CD26 expression is initiated during the G1 phase of the cell cycle. The expression occurs nearly simultaneously with HLA-DR, but later than CD25. Similar to CD25 and HLA-DR, CD26 is not a permanent marker on the surface of T-lymphocytes, but is down-regulated after 7 days of culture. When testing the influence of interleukin 1, interleukin 2, tumour necrosis factor, and interferon-gamma on the expression of CD26, no effect was found on unstimulated or on mitogen-stimulated T-lymphocytes. The binding of two different monoclonal antibodies against CD26 (anti-DPP IV and anti-Tal) to resting and activated T-lymphocytes revealed a different pattern of immunoreactivity. Resting T-lymphocytes reacted stronger with anti-DPP IV than with anti-Tal. However, binding of the two monoclonal antibodies to T-cell blasts did not show significant differences. These data indicate that CD26 may be expressed in differently modulated configurations on the surface of T-cells, which may be associated with a distinct status of activation and/or function.