title: Differential requirement for accessory cells in polyclonal T-cell activation.
abstract: Highly purified rat Ia-negative (OX-6-) and Ia-positive (OX-6+) T cells were employed to examine the requirement for accessory cells (AC) and/or soluble factors in the activation of resting T cells with Con A, PHA, sodium periodate, or antigen. A variety of cells were employed as AC, including Ia-positive and Ia-negative macrophages (M phi), gamma-irradiated (2000 rad) or non-irradiated OX-6+ T cells, and several Ia-negative adenovirus-transformed rat embryo fibroblast cell lines. Our results suggested that for the expression of IL-2 receptors (IL-2R) and proliferation of OX-6- T cells in response to Con A, PHA, or antigen, there was an obligatory requirement for the presence of AC which could not be overcome by the addition of IL-1 and/or IL-2. Activation of OX-6- T cells with antigen required the presence of Ia+ AC, while activation with mitogens could be initiated with Ia- AC. M phi were efficient in AC function in all responses tested, while the AC function of OX-6+ T cells (TAPC) proved discriminatory under different conditions. The optimal response to PHA required much higher concentrations of TAPC as AC than for the Con A response. TAPC failed to stimulate sodium periodate-treated T cells under any conditions tested. Furthermore, when TAPC were employed as AC, their antigen-presenting ability was radiosensitive, while their AC function for Con A and PHA was radioresistant. These results suggest that molecules involved in T cell-AC interactions may differ, depending on the source of AC and/or type of the proliferative stimulus provided to T cells. This data has been discussed in the context of T-cell activation.
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000502:physiology*; D003208:Concanavalin A / Q000494:pharmacology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D007375:Interleukin-1 / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology; D008213:Lymphocyte Activation; D008264:Macrophages / Q000276:immunology; D010504:Periodic Acid / Q000494:pharmacology; D010835:Phytohemagglutinins / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D011971:Receptors, Immunologic / Q000502:physiology; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000648:ultrastructure
chemical_list: D000949:Histocompatibility Antigens Class II; D007375:Interleukin-1; D007376:Interleukin-2; D010835:Phytohemagglutinins; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D010504:Periodic Acid; D003208:Concanavalin A; C009288:metaperiodate