Oral administration of lens homogenate suppresses production of lens antibodies in mice immunized with lens antigens

Purpose: Circulating autoantibodies (Ab) against lens antigens (Ag) in patients with cataract, when presented with complement, kill lens epithelial cells (LECs) in vitro. To suppress production of cytotoxic Abs, we initiated a study of the effect of oral administration of lens Ags on this immune response. Methods: Lens Ags were administered orally before and after immunization with lens Ag. Young mice (1.5 mos) were fed calf lens homogenate, 4mg/mouse, every 4 days for 5 weeks, before and after immunization with β-crystallins emulsified with CFA. Sera from these animals were analyzed by ELISA and protein blot analysis against β-crystallins. Results: The titer of Ab gradually increased to 2X10⁶ by the 5th week in the control animals. In contrast, in animals fed lens-Ag, the levels of Ab were reduced by 40-60% compared to control animals. Levels of Ab were more strongly suppressed in animals fed before immunization than after immunization. Abs against β-crystallins were suppressed by this treatment. In addition, the proliferative response of T-lymphocytes against lens-Ag was suppressed. This suppression appears to inhibit the CD4-mediated interaction either between T-cell receptor and MHC molecules on the Ag presenting cells or secretion of immune suppressive factors by T-cells.. Conclusions: Thus, oral administration of antigenic protein is a specific and non-toxic method to suppress a specific immune response to the same Ag. We are exploring the therapeutic value of oral administration of lens proteins in age-related cataract.