Role of endothelium in the pathogenesis of rheumatoid synovitis

The rheumatoid mononuclear cell infiltrate has a number of features of a cellular immune response. In the latter, the immunological specificity of the lymphocytic infiltrate is largely independent of the inciting antigen. Extensive investigation of the possible clonal or oligoclonal dominance of T-cell populations of the rheumatoid synovial infiltrate has demonstrated either no clonality or a dominance of T-cell populations with T-cell receptor V regions which have varied from patient group to patient group and, frequently, from patient to patient within a given group. These findings suggest that the basis for the mobilization of the synovial T-cell population is the activation state of the circulating T cells, not their immunological specificity, which makes them eligible for endothelial binding and transmigration. The specificity of the activated T cells of the circulating T-cell pool appears to be determined by the immunological history of the host.