摘要:

AbstractHLA class II molecules were partially purified from cells of an HLA deletion mutant cell line, LCL721.82, that lost DR and DQ expression but retained DPw2 specificity and labeled with radioactive125I. The radioiodinated preparation bound to DP‐specific monoclonal antibody B7/21 as well as rabbit anti‐HLA class II antiserum. On sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, the component involved in these bindings gave, unlike known HLA class II molecules, a sharp and dense band of ∼ 60 kDa under nonreducing conditions and a single but diffuse band of ∼ 30 kDa under reducing conditions. By screening 401 anti‐HLA class II alloantisera, including those distributed in the 9th International Histocompatibility Workshop and also those locally available, eight were found to possess significant binding activity. Specificity analysis of these eight binding‐positive antisera on a panel of DP‐pretyped HLA homozygous typing cells revealed the presence of two clusters, one corresponding to an allodeterminant associated with DPw1, 2 and 3 and the other to that associated with DPw2 and 4. These two determinants were shown by the sequential binding test to reside on the B7/21‐defined HLA class II molecules. Thus, two major conclusions were drawn: (a) two distinct allodeterminants are carried by a single DP molecule; and (b) these serologically detected DP allodeterminants are supertypic to cellularly defined DP

ISSN:0014-2980    

DOI:10.1002/eji.1830170602

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractAn analysis of function and marker expression during cytotoxic cell differentiatonin vitrofrom T cell‐depleted bone marrow precursors is described. Cytotoxic activity is not detectable during the first five days of culture, but rises abruptly soon after. Antibody plus complement depletion studies show that cytotoxic cells derive from Thy‐1‐negative precursors and undergo a continual increase in Thy‐1 and Lyt‐2 marker expression as the culture progresses. A reciprocal decrease in asialo‐GM1antigen expression on effector cells is seen. The J11d‐negative precursor cells acquire J11d (an antigen known to mark cortical thymocytes) at an intermediate stage of culture, but revert to the J11d‐negative phenotype prior to functional acquisition. At least some effectors are T cell receptor positive as illustrated by an anti‐T cell receptor antibody‐mediated killing assay. These patterns precisely correlate with those detected among developing T cellsin vivo. Results may indicate that a programmed course of differentiation inherent to bone marrow cells may be triggered in the absence of a

ISSN:0014-2980    

DOI:10.1002/eji.1830170603

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractOur results clearly demonstrate that the low‐affinity receptor for IgE (FcϵR) is an activation antigen transiently expressed on a subpopulation of human T lymphocytes. It can be selectively induced by stimulation with certain antigens or lectins, but it is not found on resting T cells. The increased numbers of activated FcϵR+T cells observed after stimulation of peripheral blood mononuclear cells (PBMC) from bee venom allergic patients with the specific allergen phospholipase A2(PLA2) suggest that FcϵR+T cells might very well be involved in the regulation of the human IgE response against the respective antigen. These results were obtained by the use of two monoclonal antibodies, M‐L25 and M‐L47, which were raised against the human low‐affinity FcϵR in our laboratory. After stimulation of PBMC with phytohemagglutinin a peak of 7,6 ± 6% FcϵR+T cells was observed on day 3, with pokeweed mitogen of 0.8 ± 0.8% on days 2 and 3, and with concanavalin A of 0.6 ± 0.7% FcϵR+T cells on day 2. Stimulation of PBMC with tetanus toxoid (TT) induced FcϵR on maximally 0.6 ± 0.8% of the total T cells (day 4), stimulation with purified protein derivative from tuberculin (PPD) on 0.2 ± 0.6% of the T cells (day 2). In contrast to these antigens, stimulation of PBMC from bee venom allergic patients with PLA2induced as a peak 2.5 ± 2.5% of the total T cells to express FcϵR (day 5), although the stimulated T cell population was much smaller than with TT or PPD, as was shown by their stimulation indices. The allergen‐stimulated FcϵR+T cells were exclusively T4+. The FcϵR‐expression index was determined, which for a specific antigen or lectin correlates the percentage of FcϵR+T cells to the stimulated T c

ISSN:0014-2980    

DOI:10.1002/eji.1830170604

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractCyclosporin A (CsA) produced dose‐dependent membrane depolarization of human peripheral blood lymphocytes. The phenomenon was investigated applying the membrane potential probe dihexyloxacarbocyanine iodide in a flow cytometer in combination with ionophores, hormones and monoclonal antibodies binding to different subclasses of lymphocytes and the anti‐interleukin 2 receptor antibody. Human interferon‐γ abolished the depolarizing effect of cyclosporin on lymphocytes. Interleukin 2 caused depolarization and also enhanced the effect of CsA. OKT4 and OKT8 monoclonal antibodies slightly hindered depolarization by CsA while OKT3, OKT11 and OKIa1 antibodies had no such effect. Valinomycin decreased CsA's effect on the membrane potential while the ionophore A‐23187 and ionomycin caused depolarizations that were additive with CsA's. CsA treatment released the isotope from42K‐loaded human lymphocytes in a dose‐dependent fashion. CsA addition increased intracellular calcium content. CsA decreased the motional freedom of a spin probe in the membrane, but did not hinder the binding of fluoresceinated antibodies to the cell surface. These results suggest immediate alteration in membrane structure upon CsA treatment, causing potassium leakage and calcium ion uptake. These are the earliest detected effects of CsA on

ISSN:0014-2980    

DOI:10.1002/eji.1830170605

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractTen consecutive 15‐residue peptides (except for peptide 181–198) that spanned the entire second domain of the HLA DR2 β chain and overlapped by 5 residues were synthesized, purified and characterized. The antibody‐binding activities of the peptides with human alloantisera and with antisera raised in other species were determined by radioimmunosorbent titrations. This established the full profile of peptides having specific antibody‐binding activity with these various antisera. The continuous antigenic sites in this domain were localized within four regions. The localization of the antigenic regions on the second domain completes the description of the antigenic profile of the entire extracellular part of the β chain of HLA DR2. Thus, the continuous antigenic sites on the extracellular part of the DR2 β subunit reside within seven regions with an eighth site being recognized somewhat weakly with some antisera. As was found for the first domain, the immunodominance of a given site varied with the antisera and boundary shifts were present. The submolecular regions recognized on the second domain of the DR2 β were independent of the host species from which the antisera we

ISSN:0014-2980    

DOI:10.1002/eji.1830170606

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractThe data presented in this report describe an antigen‐independent activation pathway leading to reinduction of proliferation of class II major histocompatibility complex (MHC)‐restricted murine T cell lines that after previous antigen‐specific stimulation reverted to a resting state. Antigen‐independent proliferation and interleukin 2 (IL 2)‐receptor expression occur in the presence of splenic accessory cells, exogenous IL 2 and a soluble factor(s) provisionally termed T cell‐stimulating factor(s) (TSF). Each of these components is essential for inducing growth. TSF is found in the supernatant of an autoreactive T cell line upon stimulation with syngeneic accessory cells. Neither TSF nor accessory cells can be replaced by IL1 and by some other cytokines. Monoclonal antibodies against class IIMHC molecules, the T cell receptor and L3T4 do not block this antigen‐independent stimulation. This demonstrates that the function of the accessory cell in this system is not MHC restricted and that the T cell receptor is also not involved. Furthermore, it is suggested that the blocking of L3T4 molecules by antibody will mediate a negative signal only if T cells are triggered via their anti

ISSN:0014-2980    

DOI:10.1002/eji.1830170607

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractWe have analyzed different parameters of the interleukin 2 receptor (IL 2R) traffic in a murine IL2‐dependent T cell line, B6.1. These cells express about 105IL 2R, of which approximately 10% are of high affinity (HAR). About 90% of all mature immunoprecipitable receptor molecules in the cell are on the cell surface. Measurements of the half life and of the rate of receptor synthesis indicate that these cells produce approximately 500 receptor molecules per cell and min. IL2 deprival for less than 6 h does not affect this rate.B6.1 cells internalize IL2 via their HAR only, with a maximal rate of about 500 molecules per cell and min. Among the receptors present at a given time on the cell surface, about 15% are internalized within 30 min. Receptor internalization is independent of IL2. The data obtained argue against rapid recycling of the HAR. The rate of receptor synthesis can be reconciled with the rate of IL2 internalization and the observation that internalization occurs only via HAR by assuming that cell surface low‐affinity receptors can be transformed into HAR by associating with other molecu

ISSN:0014-2980    

DOI:10.1002/eji.1830170608

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractUponin vitroactivation byStaphylococcus aureusCowan I strain (SAC) human peripheral blood B cells produce only marginal amounts of Ig when cultured in the presence of interleukin 2 (IL2; 10 U/ml). This response is only moderately increased by the addition of monocytes or of IL1. In the presence of dexamethasone (DM; 10−7−10−8M) microgram amounts of both IgM and IgG are produced in co‐cultures of B cells and monocytes. This response is not modified by inhibitors of cyclooxygenase and is specifically inhibited by a monoclonal antibody interfering with the binding of IL2 to its receptor. This enhancing effect of DM is not observed in the absence of monocytes even if IL 1 is added to the cultures. Moreover, monocytes pretreated with DM stimulate the response of B cells cultures in the absence of DM. Enhancement of Ig production by DM and monocytes could be demonstrated with B cells obtained from a patient suffering from a hyperlymphocytic form of B cell type chronic lymphocytic leukemia, and in this case only IgM was produced. Importantly, DM fully inhibited the IL2‐dependent proliferation of these monoclonal B cells. Thus, physiological concentrations of DM can modulate monocytic function to enhance the differentiative effe

ISSN:0014-2980    

DOI:10.1002/eji.1830170609

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractUsing a culture system which supports primary T cell proliferative responses to various antigens we have detected mouse red blood cell (RBC)‐reactive T cells in lymphoid tissues from untreated mice. The release of significant amounts of interleukin 2 (IL2) indicates that T helper (or helper/inducer) cells are activated by stimulation with RBC. Upon restimulationin vitrothese cells proliferate specifically against mouse RBC with the kinetics and magnitude characteristic of a secondary response. Since autologous RBC are toleratedin vivoin spite of the presence of such specifically reactive T helper cells, these findings imply that self tolerance, even to certain nonse‐questered antigens, may depend largely on regulatory mechanisms rather than on clonal deletion or inactivat

ISSN:0014-2980    

DOI:10.1002/eji.1830170610

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractTumor‐promoting phorbol esters (PE) can modulate cellular functions and cell surface determinant expression in a variety of cell types, including T lymphocytes, presumably by activating the enzyme, protein kinase C (PKC). To examine whether PKC might be involved in regulating the expression of genes encoding the antigen‐specific T cell receptor (TCR), we cultured the murine thymoma line, EL4, in the presence of 12‐O‐tetradecanoylphorbol 13‐acetate (TPA) and analyzed the expression of TCR α or β‐chain genes by Northern blots. TPA stimulation of an interleukin 2 (IL 2)‐producing variant, EL4+, induced a 3–4‐fold increase in TCR β, but not α, chain mRNA. Maximal increase was obtained with 3 ng/ml TPA and 12 h of stimulation. This effect appeared related to PKC activation because other tumor‐promoting PE known to be PKC activators, but not inactive PE, induced the same increase. TPA stimulation of EL4+cells also inducedde novoexpression of the IL 2 gene and subsequent secretion of this lymphokine. However, the increased expression of the TCR β‐chain gene and the induction of the IL 2 gene were not linked since (a) expression of TCR β‐chain mRNA was increased to a similar degree in EL4+and IL 2‐nonproducing EL4−sublines, and (b) cyclosporin A selectively blocked TPA‐induced IL 2‐gene expression in EL4+cells without affecting the increase in TCR β‐chain mRNA. These findings suggest that PKC activation, an event that supposedly occurs after antigen‐mediated triggering of the TCR, can regulate the expression of at leas

ISSN:0014-2980    

DOI:10.1002/eji.1830170611

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY