In summary, our data suggest that oral tolerance in the mouse EAU model may occur by anergy/deletion or by suppression, depending on the feeding regimen. Tolerance involving putative regulatory cells appears to require the ability to produce both IL-4 and IL-10, whereas induction of tolerance involving anergy may not require the presence of Il-4 and IL-10. We propose that regulatory cells induced by three feedings of IRBP can be selectively enhanced through the use of cytokines. From the point of view of clinical therapy, it would be worthwhile to explore postimmunization feeding regimens involving administration of IL-4 and IL-10.