T cell regulatory disturbances in the rheumatic diseases

Significant immunoregulatory abnormalities have been described in both SLE and RA. In SLE, deficient suppressor T cell activity may result from depletion of CD8+ suppressor precursors, depletion of CD4+ suppressor-inducer cells, or impaired lymphokine production and deficient CD4+ cell activation of suppression by CD4+ cells. The net result is an apparent failure to inhibit antibody synthesis. The defects in RA are less well defined, although in RA there also is evidence that either deficient suppression or deficient suppression-induction plays a role in the pathogenesis of disease. There is evidence for local lymphocyte activation in the synovium, with possibly impaired local immunoregulation. However, the precise nature of the immune reactions in the synovium and their relationship to systemic immunoregulatory abnormalities remain unclear.