Intraocular Ia expression in vivo induced in the absence of immune T cells

The expression of Ia antigen on the ciliary body, retinal pigment epithelium, and retinal vascular endothelium was investigated using two models of ocular inflammation. Active systemic immunization with bovine serum albumin with subsequent ocular challenge resulted in increased Ia expression in the ciliary body and retinal pigment epithelium. This was compared with passive transfer of hyperimmune serum to bovine serum albumin followed by ocular challenge when Ia expression was found to occur only in the ciliary body. An intraocular T-cell infiltrate occurred only in the actively immunized animals and was not present after passive transfer, suggesting that the Ia induction in this latter situation occurred in the absence of T cells.