NEUTROPHIL AND RECOMBINANT MYELOPEROXIDASE AS ANTIGENS IN ANCA POSITIVE SYSTEMIC VASCULITIS

Myeloperoxidase (MPO) is one of the major autoantigens recognized by a nti-neutrophil cytoplasm antibodies. The association of this antigen w ith specific disease entities requires that there is a source of pure antigen present in large quantities. Further delineation of the molecu lar mechanisms involved in the antigen-antibody interaction requires t he ability to manipulate the molecule. The expression of recombinant M PO in Chinese hamster ovary cells has produced a source of pure protei n, suitable for molecular studies. We have shown that this protein is an antigen recognized by 95% of anti-MPO antibodies from patients with systemic vasculitis. This recombinant molecule will be of use in prov iding an additional specific solid-phase assay for these antibodies an d further forms of this protein which mirror the antigenicity of nativ e MPO more exactly may replace chemically purified antigen. It will al so be of great value in studies examining the epitopes recognized by a nti-MPO antibodies and in studies of immunoregulation and T cell activ ation.