Responsiveness of human T lymphocytes to bacterial superantigens presented by cultured rheumatoid arthritis synoviocytes. Arthritis Rheum

Objective. Type B fibroblastic synoviocytes are abundant in inflamed joints of patients with rheumatoid arthritis (RA), and can secrete cytokines and other mediators of inflammation. The aim of this study was to determine whether cell lines derived from RA type B synoviocytes could also serve as accessory cells for T lymphocyte activation. Methods. Cells from RA synoviocyte lines, with or without preculture in interferon- y (IFNy), were cultured with purified peripheral blood T cells, in the presence or absence of superantigens or other accessory cell-dependent T cell mitogens. T cell proliferation was measured by thymidine incorporation, and synoviocyte surface markers were analyzed by flow cytometry. Resuh. RA type B synoviocyte lines were potent accessory cells for T cell responses to bacterial super-antigens or lectins, and direct cell-cell contact was required. Preculture in IFN y augmented synoviocyte expression of major histocompatibility complex (MHC) class II molecules and of ligands for some T cell costim-ulatory receptors, but synoviocyte accessory cell func-tion was evident even in the absence of IFNy. Blocking studies using monoclonal antibodies supported the no-tion of a role for CD2, CDlldCD18 and MHC class I1 molecules in synoviocyte-dependent T cell activation