MOLECULAR AND IMMUNOLOGICAL CHARACTERIZATION OF HR44, A HUMAN OCULAR COMPONENT IMMUNOLOGICALLY CROSS-REACTIVE WITH ANTIGEN OV39 OF ONCHOCERCA-VOLVULUS

Structural similarities between host self-antigens and infectious orga nisms may be involved in the expression of autoimmune reactivity and d evelopment of autoimmune disease. The unique eye pathology associated with Onchocerca volvulus infection, particularly the development of po sterior segment lesions, may be promoted by such autoreactive response s. Ov39 is a parasite-derived antigen that has been shown previously t o be antigenically cross-reactive with a 44,000-M(r) host ocular compo nent. A clone, designated hr44, was isolated from a cDNA library of hu man retina by immunoscreen using serum to Ov39. A monoclonal antibody raised to Ov39 also reacted with hr44 and gave evidence for a shared c onformational epitope. The primary structure analysis showed that iden tities between the antigens are limited and confined to small peptides . The cross-reactivity between the antigens appears to involve T cells , since Ov39-specific T cells can be stimulated by hr44, a neural-spec ific antigen. Based on secondary structure prediction, hr44 has the ty pical features of a membrane-associated type I antigen with an amino-t emminal extracellular domain. mAbs and antisera localized the antigen in the optic nerve, neural retina, retinal pigment epithelium, as well as the epithelial layers of ciliary body and iris.