Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0033036 (APC)
 10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The glycosylation inhibiting factor (GIF) was detected in EGTA extracts of the OVA-specific Ts cell hybridoma, 231F1 cells and 71B4 cells, which constitutively secrete GIF. The lymphokine in both culture supernatants and EGTA extracts failed to bind to OVA-Sepharose. Association of GIF with the plasma membrane was confirmed by surface labeling of the 231F1 cells with 125I. The major species of GIF in the extract was 14.4-kDa peptide as determined by SDS-PAGE, and was identical to that detected in culture supernatants. Pretreatment of the cells with monoclonal anti-GIF switched the cells from the formation of unglycosylated IgE-BF to the formation of glycosylated IgE-BF, indicating that the membrane-associated GIF is involved in the determination of the nature of IgE-binding factor during their biosynthesis. When the hybridoma was stimulated with OVA-pulsed APC, EGTA extracts of the cells contained GIF having affinity for OVA. The binding of the OVA-binding GIF in the EGTA extracts to OVA-Sepharose was inhibited by a synthetic peptide, which corresponds to amino acid residues 307-317 in the OVA molecule and represents the epitope recognized by TCR on the cells. The OVA-binding GIF in the extracts bound to the monoclonal anti-TCR-alpha chain, H-28-710 and the mAb 14-12, which is specific for the Ag-binding chain of effector type suppressor factor, and suppressed the in vivo antibody response of BDF1 mice to DNP-OVA in a carrier-specific manner. Evidence was obtained that indicated that the Ag-binding chain was associated with nonspecific GIF chain on the cell surface of the Ag-stimulated cells.
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PMID:Association of glycosylation-inhibiting factor with plasma membranes of T suppressor cell hybridomas. 214 96

We have used double-immunofluorescence labeling to determine the surface distributions of LFA-1 and CD4, and the intracellular distributions of the cytoskeletal protein talin and of the microtubule organizing center (MTOC) of cloned Th cells in 1:1 cell couples with antigen (Ag)-specific APC of the B cell type (B-APC). The Th cell was directed to a peptide fragment of the Ag OVA in the context of IAd. The B-APC was the transfected A20 B hybridoma cell A20-HL, bearing on its surface a surface Ig specific for the hapten TNP, and pulsed with different concentrations of DNP-OVA. At sufficiently high doses of DNP-OVA (greater than 100 ng/ml), in essentially all couples, LFA-1, CD4, and talin were each concentrated at the Th cell membrane where it was in contact with the B-APC, and the MTOC inside the Th cell was reoriented to face the contact region. At lower doses of DNP-OVA (between 50 and 10 ng/ml), in all couples, LFA-1 and talin were concentrated at the Th/B-APC contact region, but the extent of CD4 clustering, MTOC reorientation, and Th cell proliferation all decreased with decreasing Ag dose. With no Ag, none of these effects was observed. These and other data indicate that two distinct signals are received by the Th cell that is specifically bound to its B-APC. The first signal, at low Ag doses, stimulates a linkage of LFA-1 and talin in the Th cell, and a specific LFA-1-mediated intercellular adhesion; the second signal, at higher Ag doses, is required to induce Th cell proliferation, with which the Th-MTOC reorientation and CD4 clustering are correlated.
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PMID:The specific interaction of helper T cells and antigen-presenting B cells. IV. Membrane and cytoskeletal reorganizations in the bound T cell as a function of antigen dose. 253 Mar

Langerhans cells (LC) that have been cultured for 3 days acquire potent T cell-activating properties when compared to freshly prepared, uncultured LC. By contrast, fresh LC are superior to cultured LC in the ability to process native protein Ag. To define further the disparate functional properties of these epidermally derived APC, freshly isolated and cultured epidermal cells (EC) enriched for LC were prepared from BALB/c mice. Highly purified T cells from naive mice, and from mice sensitized epicutaneously with dinitrofluorobenzene, have been examined for their capacity to respond to fresh and cultured EC; 1) in the presence of staphylococcal enterotoxin B; and 2) after the EC had been derivatized with dinitrofluorobenzene. Both fresh and cultured EC activated syngeneic T cells in the presence of staphylococcal enterotoxin B, and fresh and cultured DNP-derivatized EC induced proliferation among DNP-specific T cells. Only cultured, hapten-derivatized EC were able to activate unprimed syngeneic T cells in vitro, and these cells responded as though "primed" when re-exposed to DNP-derivatized spleen cells in secondary cultures. In addition, naive lymphocytes that were activated by cultured DNP-EC were able to evoke local contact hypersensitivity reactions when injected into the pinnae of naive mice that were then painted with dinitrofluorobenzene. By contrast, naive syngeneic T cells exposed to fresh DNP-EC neither proliferated nor differentiated into effector cells. We conclude that fresh LC can constitutively activate primed, but not unprimed, hapten-specific T cells, whereas cultured LC readily both primed and unprimed T cells. The capacity of hapten-derivatized cultured EC to convert naive, hapten-specific T cells into cells that mediate contact hypersensitivity supports the proposal that cultured LC are the functional equivalents of epidermal LC that have migrated to draining lymph nodes. The ability of hapten-derivatized fresh LC to activate primed, hapten-specific T cells is consistent with the view that fresh LC are functionally equivalent to LC within the epidermis.
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PMID:Fresh and cultured Langerhans cells display differential capacities to activate hapten-specific T cells. 841 31