title: Role of Ia-positive cells in the lymphocyte responses to Yersinia.
abstract: Activation of T lymphocytes by an antigen requires joint recognition of the antigen and the class-II HLA determinants on the membrane of the antigen-presenting cells (APC). Patients with reactive arthritis exhibit a depressed lymphocyte transformation response to Yersinia, suggesting a possible immunoregulatory disturbance in these patients. In this study the role of Ia (class-II HLA antigen)-positive APC in the lymphocyte response to a complex antigen, whole Yersinia bacterium, was evaluated. The results demonstrate that Ia-positive cells are necessary for the T-lymphocyte response to Yersinia. The role of APC in the pathogenesis of reactive arthritis is discussed.
mesh_terms: D000911:Antibodies, Monoclonal; D001168:Arthritis / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D000949:Histocompatibility Antigens Class II; D006801:Humans; D007108:Immune Tolerance; D008213:Lymphocyte Activation; D008297:Male; D015009:Yersinia Infections / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II