[Active immune regulation by cells of the ciliary body]

Immunoregulation in the eye requires both an effective defense against exogenous pathogens and protection of the delicate anatomy of the eye against "innocent bystander destruction", which accompanies inflammatory reactions. We studied the role of uveal cells for local immunoregulation in the eye and investigated the effect of cultured Lewis rat ciliary body cells on antigen-specific 3[H]-thymidin incorporation in a T-helper-lymphocyte cell line (ThS) specific for the retinal-soluble antigen (SAg). Ciliary body cells inhibit the proliferation of ThS. This inhibition is not species-specific and is mediated by at least two mechanisms: a soluble inhibitor and a contact-requiring factor that is trypsin-sensitive, suggesting a protein molecule. After removal of these inhibitory components, ciliary body cells also exhibit the capacity to effectively present SAg to ThS. This dual effect of ciliary body cells on T-helper lymphocytes supports the concept of active local immunoregulation in the eye.