Phagocytosis and killing ofTrypanosoma dionisiiby human neutrophils, eosinophils and monocytes

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Abstract
SUMMARY: The cell-mediated resistance of human leucocytes toTrypanosoma dionisii, a bat parasite related toT. cruzi, was investigated. Human peripheral blood neutrophils and monocytes were cytotoxic toT. dionisiias assessed by electron microscopy and by induction of99mTc release from trypanosomes pre-labelled with [99mTc]pertechnetate. The enhancement of cytotoxicity by specific antiserum varied considerably from one individual to another. Neither blood lymphocytes nor blood eosinophils induced99mTc release fromT. dionisii. The trypanosomes were readily phagocytosed by neutrophils and monocytes even in the absence of added antiserum but the rate was enhanced when antiserum was present. Eosinophils also phagocytosedT. dionisiibut only in the presence of antiserum. Investigation by electron microscopy revealed thatT. dionisiiis rapidly destroyed in the phagocytic vacuole of neutrophils and monocytes and by eosinophils. Phagocytosis, ultrastructural damage and induction of99mTc release occurred more rapidly in neutrophils than in monocytes.