Characterization of Inflammatory Infiltrates in Chronic Chagasic Myocardial Lesions: Presence of Tumor Necrosis Factor-α+ Cells and Dominance of Granzyme A+, CD8+ Lymphocytes

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  • Departamento de Bioquimica e Imunologia, Universidade Federal de Minas Gerais, Departamento de Patologia, Faculdade de Medicina do Triangulo Mineiro, Centro de Pesquisas Rene Rachou, FIOCRUZ, Department of Pathology, Vanderbilt University Medical Center, Departments of Microbiology and Immunology, and Medicine, Vanderbilt University School of Medicine and Veterans Administration Medical Center, Belo Horizonte, Brazil

The inflammatory infiltrates in the heart lesions of chronic chagasic cardiomyopathy are composed predominantly of small lymphocytes with admixed macrophages, plasma cells, and segmented leukocytes. The phenotypes of the lymphoid cells in these infiltrates of human Chagas' disease have not been previously detailed. We used a panel of monoclonal and polyclonal antibodies to immunohistochemically characterize the inflammatory cells in frozen and fixed cardiac tissues from autopsied patients with severe chronic chagasic cardiomyopathy. In all cases, the inflammatory lesions were dominated by CD8+ lymphocytes, many of which expressed granzyme A. A few macrophage-like cells that expressed tumor necrosis factor-α were observed in each case. Relatively few natural killer cells or B lymphocytes were found in the lesions. These findings in human chagasic lesions are compatible with concepts that involve cytolysis and fibrosis, and new experimental findings that emphasize potential roles for CD8+ T cells in Chagas' disease.