Auto-antibodies (Abs) against lens antigens (Ags) are present in most patients with age-related cataract, and with complement they kill lens epithelial cells (LECs) in vitro. We studied, in an animal model, whether cytotoxic Abs against lens Ags can be suppressed by oral administration of the Ags. Mice were fed calf lens homogenate, 4 mg/mouse, every 4 days for 4-5 weeks, or bovine serum albumin (BSA) before and after immunisation with beta-crystallins emulsified in complete Freund's adjuvant (CFA). Sera from these animals were analysed for Abs to beta-crystallins by enzyme-linked immunosorbent assay (ELISA) and protein blot analysis. In addition, we studied the proliferative response of T-lymphocytes to beta-crystallins. The titer of anti-beta-crystallin Abs in the control animals fed BSA gradually increased to 1.5 x 10(-6) by the 5th week after the first injection. In contrast, the titer of anti-beta-crystallin Abs in animals fed calf lens homogenate was reduced to 30-70% of the control. Feeding lens homogenate prior to or concomitant with beta-crystallins immunization, was more effective than feeding after immunization (65% suppression vs. 30% suppression, respectively). Also the proliferative response of T-lymphocytes to beta-crystallins in mice fed homogenate was suppressed significantly. Thus, oral administration of lens homogenate is a specific and nontoxic method of suppressing anti-beta-crystallin Ab production in mice. We are exploring the therapeutic value of oral administration of lens proteins in age-related cataract.