Activated T and B lymphocytes in peripheral blood of patients with Chagas' disease

Whole blood preparations from patients with either the indeterminate(asymptomatic) or cardiac clinical forms of chronic Trypanosomacruzl infection were analyzed by flow cytometry using double-labelingto identify subsets of circulating lymphocytes. Several significantdifferences were demonstrated between the blood lymphocyte profilesof chagaslc patients and non-chagaslc controls. Clear increasein the percentages and actual numbers of double-positive cellsof the phenotype CD3⁺/HLA-DR⁺, as well as decrease in the percentageof CD45RA⁺/CD4⁺ and CD45RA⁺/CD8⁺ T cells, Indicate greater numbersof activated T cells circulating in the blood of infected patients.Consistent parallel increases were seen also in the B lymphocytesubset which stained double-positive for CD19/CD5. There wereno significant differences in the circulation of these chronicchagaslc patients in the CD4:CD8 ratios. Also, no substantivephenotyplc differences were observed in the lymphocyte populationsbetween the two ends of the clinical spectrum (Indeterminateversus cardiac) in chronic human Chagas' disease. These observationsdemonstrate that increased levels of activated T cells and CD5⁺B cells are present in the circulation of people with chronicChagas' disease. These are cell phenotypes that have been associatedin other conditions with autoimmune, polyclonal, and hyperlmmuneresponses. The specificities of these activated cells and theroles they may play in resistance or pathogenesis during chronicChagas' disease need now to be determined.