SUPPRESSION OF ALLERGIC UVEITIS BY 6-MERCAPTOPURINE

Abstract

These experiments clearly demonstrated that 6-MP will inhibit the appearance of allergic uveitis following a single intraocular injection of bovine serum albumin in rabbits. These findings were evident both at the clinical and histological levels. The results appeared to be due to interference with the immune responses since a good correlation was demonstrated between the antibody titers and the height of uveitis in both the control, and 6-MP animals during the period of treatment. The treated animals revealed a slow rise of serum antibody titer when 6-MP was discontinued, but at the termination of the experiment, a significant difference in the titers of the two groups was still clearly evident. The aqueous protein determinations revealed a significantly lower content in treated animals. There was a rough correlation between the degree of uveitis and the protein content in all animals studied. The findings of lower protein content in the treated group served as a further check on the clinical evidence that 6-MP suppressed the allergic uveitis. The histologic findings also bore out the clinical findings that 6-MP suppressed the inflammatory allergic response. The tissue changes that appeared during the course of therapy were less marked than those observed in the controls. During treatment many eyes showed no uveitis at all. The specific cellular response and its manner of distribution in tissues of the eyes were qualitatively similar in both groups. Animals treated with 6-MP in this experiment revealed no significant difference in the clinical picture or histologic findings of the initial reaction to the trauma of antigen injection when compared to the control group, indicating that the drug had no appreciable anti-inflammatory effects.