CD8 T-CELLS ARE NOT ESSENTIAL FOR THE INDUCTION OF LOW-DOSE ORAL TOLERANCE

To examine whether CD8 T-cells are essential for the induction of ''lo w-dose'' oral tolerance, we tested animals deficient in CD8 T-cells, i .e., Lewis rats in which CD8 cells were eliminated by injections of sp ecific antibodies and beta 2m(-/-) mice in which the CD8 cells are sca rce and poorly functional. Oral tolerance was induced in the rats by r epeated feedings with the uveitogenic retinal S-antigen, while in the mice the fed antigen was ovalbumin. Feeding reduced in both species th e specific cellular immune response, measured by the lymphocyte prolif eration assay. In the rats, this treatment also inhibited the developm ent of the inflammatory eye disease, experimental autoimmune uveoretin itis. In addition, the levels of specific antibodies in the fed animal s were moderately lower than those in their controls. Both the CD8-dep leted rats and the beta 2m(-/-) mice resembled their normal controls i n demonstrating reduced immune responses following feeding with the co rresponding antigen. This observation thus indicates that CD8 T-cells are not essential for the induction of low-dose oral tolerance. (C) 19 96 Academic Press, Inc.