Interferon gamma production by PAS-positive T lymphocytes of chagasic patients infiltrated into human hearts in the sites of lesions.

Unlabelled: In the blood of chagasic patients, a high number of T-lymphocytes producers of a PA.S.-positive substance was found, more numerous in chagasics with abnormal electrocardiogram. Further, we found such lymphocytes infiltrated in the chagasic heart. Here, we considered our hypothesis that those lymphocytes would be Interferon -gamma producer' cells.

Material And Methods: Heart samples of 8 patients deceased due to chagasic heart disease (ChHD). Cuts of 5 microns were submitted to monoclonal antibodies for human Interferon-gamma; to CD45RO for activated T lymphocytes; and to the classical Periodic acid Schiff reaction (P.A.S.), respectively. In blood smears from chagasic patients with ChHD, the reactivity for anti Interferon gamma and for the P.A.S. reaction was compared, regarding the respective positive cell number. The myocardium status was compared with clinical date.

Results: In hearts, 65-75% of infiltrated lymphocytes were positive for IFN-gamma; similar values were found , in seriated cuts, of P.A.S.-positive lymphocytes, as well as of CD45RO+. In blood, there were 41%+/-9 of P.A.S.-positive lymphocytes, similar to positive cells for IFN-gamma.

Conclusions: The data indicates that the P.A.S.-positive lymphocytes from chagasic patients are producers of IFN-gamma in blood, as well as when infiltrated into the cardiac tissues. Such fact explains also the great affluence of macrophages in cardiac tissues in ChHD. The data indicate a strong response of T helper 1 type in this severe advanced stage of Chagas'disease. Neither Typanosome cruzi parasites or intracellular forms were seen in these hearts. This favors the data showing autoimmune mechanisms in this process. We open a question: to which antigen/s respond in the chagasic hearts the lymphocytes producers of IFN-gamma?