The effect of cyclophosphamide on a secondary ocular immune response in rabbits.

Treatment of rabbits with immunosuppressive doses of cyclophosphamide during the primary response to intravitreally injected bovine gamma globulin did not prevent priming for a secondary response to the same antigen. High antibody titers were found in the aqueous humor and serum of most of the treated rabbits. Ocular tissue plaque forming cell numbers were similar to those of the controls in many of the rabbits, and slightly lower in others. Treatment with cyclophosphamide completely suppressed the ocular immune response in many rabbits that had undergone a primary response following intravitreal injection of BGC. The response in other animals was depressed but not completely inhibited. The presence of ocular inflammation and lymphocytes in the challenged eyes of the treated rabbits suggested a differential effect of cyclophosphamide on cells stimulated to divide after challenge.