LYTIC MONOCLONAL-ANTIBODY TO TRYPANOSOMA-CRUZI BLOOD-STREAM TRYPOMASTIGOTES WHICH RECOGNIZES AN EPITOPE EXPRESSED IN TISSUES AFFECTED IN CHAGAS-DISEASE

It has been suggested that molecular mimicry between the antigens of T rypanosoma cruzi and the host could have a role in the onset of the ch ronic stage of Chagas' disease. In this article, we report on a monocl onal antibody (MAb), CAK20.12 (immunoglobulin G2b), which reacts with a polypeptidic epitope of a 150-kDa antigen expressed on the surface o f several strains of T. cruzi. This MAb also causes lysis of bloodstre am trypomastigotes. Serum samples from 30 of 30 patients with chronic and 11 of 13 patients with acute Chagas' disease present specific anti bodies to this antigen. MAb CAK20.12 reacts, by indirect immunofluores cence, with human and syngeneic murine striated muscle tissue, with th e smooth muscle layer of cardiac arteries, with the lamina muscularis mucosae and the external striated muscle layer of the esophagus, and w ith the smooth muscle cells of the colon from normal syngeneic mice. R eactivity with the small intestine was very weak, and no reactivity wi th ventricle or atrium tissue was detected. Adsorption with an antigen ic fraction from normal murine striated muscle or from T. cruzi epimas tigotes confirmed that MAb CAK20.12 recognizes a common epitope presen t in parasites and host tissues. MAb CAK20.12, lytic for the infective form of T. cruzi, recognizes an epitope expressed in striated and smo oth muscle cells of the host tissues affected in the chronic stage of Chagas' disease.