CD4 and rheumatoid arthritis: To examine whether synovial monocytes in RA patients have a unique capability to modulate T-cell responses, we conducted crisscross cocultures using CD4 memory T cells and monocytes from the synovial fluid and peripheral blood of the same RA patients for 7 days in the presence of soluble anti-CD3, anti-CD28 antibodies and LPS (Fig. 8A).