IL33 and vasculitis: To directly assess the role of IL-33 in EAU development, we administered recombinant IL-33 i.p. to IRBP-immunized mice as described in the “Material and methods.” On day 18 after immunization, PBS-treated control mice developed retinal inflammation with swelling of the optic disc, diffuse whitish retinal exudates in the retina, and signs of vessel inflammation (vasculitis) (Fig.3A).