Role of HLA class II and cytokine expression in rheumatoid arthritis

HLA class II expression is notable in rheumatoid arthritis. We have investigated the mechanism of HLA class II regulation in the joints and found local synthesis, as judged by mRNA levels to be high. The role of antigen presentation in maintaining class II mRNA was explored, and blocking presentation by using monoclonal antibodies to HLA class II inhibited synthesis of mRNA for HLA-DR alpha chain. HLA class II expression is maintained by cytokines and so cytokine production in rheumatoid joints was investigated. It was chosen to use mRNA analysis by slot blotting as a screening assay, and the expression of many cytokines was detected. Levels of these were maintained in culture in the absence of extrinsic stimulation.