Tissue immune effector cells and epithelial surface antigens present in eye tissue of rheumatoid arthritis (RA) patients with sterile corneal ulceration were studied using a large panel of monoclonal antibodies. During periods of active corneal ulceration, conjunctivae and corneas of all RA patients studied contained numerous immune-associated (Ia) antigen-positive tissue macrophages. In 4 of 6 patients, conjunctival or corneal T cell infiltrations were present. In 2 patients, a T cell vasculitis was seen in conjunctival tissue. Conjunctival epithelial cells of all 6 RA patients expressed Ia antigens during active corneal ulceration. These data provide evidence for immune-mediated mechanisms in the pathophysiology of corneal ulceration in RA. Moreover, the expression of Ia antigens by conjunctival epithelial cells may be a useful indicator of disease activity in RA patients with sterile corneal ulceration.