MHC restriction of synovial fluid lymphocyte responses to the triggering organism in reactive arthritis. Absence of a class I-restricted response

Abstract

Synovial fluid mononuclear cells (SFMC) from patients with reactive arthritis (ReA) show marked proliferative responses to preparations of the organism triggering the arthritis. Initial studies with MHC‐specific MoAbs have indicated that a significant element of these proliferative responses is mediated by class II MHC‐restricted CD4⁺ T cells. It is imperative to establish the presence or absence of a class I‐restricted response, for two reasons. Firstly, the association of ReA with the MHC class I molecule. HLA B27, raises the possibility of there being a B27‐restricted response to the triggering organism. Secondly, a number of the organisms associated with ReA are intracellular pathogens, whose antigens might be expected to be presented by class I MHC molecules. In an effort to identify a class I MHC‐restricted pathogen‐specific response in the SFMC of ReA patients, we have assessed the proliferative responses of SFMC depleted of CD4⁺ T cells. Responses were grossly diminished by CD4⁺ T cell depletion. We also investigated Chlamydia‐specific cytotoxicity in the SFMC of patients with sexually acquired ReA in a system using productive chlamydial infection to produce both targets and effectors. Significant antigen specific cytotoxicity was not seen. These experiments do not provide evidence to support the existence of pathogen‐specific responses by CD8⁺, class 1‐restricted synovial fluid T cells in ReA.