title: Different requirements for Ia-bearing accessory cells in mitogen versus antigen induction of human B-cell responses.
abstract: The accessory cell requirements for the induction of proliferative and specific antibody responses of human lymphocytes stimulated with either antigen or mitogen were examined. An Ia-negative human myeloid tumor cell line, K562, could substitute for monocytes in the proliferation of monocyte-depleted lymphocytes in response to pokeweed mitogen (PWM) stimulation. K562 cells could also act as accessory cells in the PWM-induced anti-keyhole limpet hemocyanin (KLH) antibody synthesis of cells from a KLH-immunized donor. In contrast, only monocytes and not K562 cells could function as accessory cells in antigen-induced lymphocyte proliferation as well as in antigen-induced, antigen-specific antibody production. However, K562 cells, like monocytes, were able to positively and negatively regulate polyclonal immunoglobulin responses. Thus, Ia-bearing accessory cells can function in antigen-induced proliferation and antibody responses while non-Ia-bearing cells can function in mitogen-induced, but not antigen-induced responses. These studies indicate a dichotomy in the nature of required accessory cells in antigen-induced versus mitogen-induced human lymphocyte responses and strongly suggest an obligatory role of Ia or an Ia-related molecule on accessory cells in antigen-induced responses of human lymphocytes.
mesh_terms: D000818:Animals; D000917:Antibody Formation; D000941:Antigens / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D006433:Hemocyanins / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D006801:Humans; D007375:Interleukin-1 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D051379:Mice; D008934:Mitogens / Q000494:pharmacology; D009000:Monocytes / Q000276:immunology*; D011043:Pokeweed Mitogens / Q000494:pharmacology
chemical_list: D000941:Antigens; D000949:Histocompatibility Antigens Class II; D007375:Interleukin-1; D008934:Mitogens; D011043:Pokeweed Mitogens; D006433:Hemocyanins