Phagocytosis and killing ofTrypanosoma dionisiiby human neutrophils, eosinophils and monocytes

Abstract

SUMMARYThe 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.

Eosinophils in innate immunity: an evolving story

“…Cline et al (1968) later showed in vitro phagocytosis of Gram-positive Staphylococcus aureus and Gram-negative Escherichia Coli bacteria, and living and dead Candida albicans , by human eosinophils purified from patients with eosinophilia. Eosinophils have also been shown to phagocytose and destroy parasites such as T. dionisii , but only in the presence of antiserum (Thorne et al 1979). Eosinophilic phagocytosis is accompanied by degranulation and involves lysosomal enzymes, similarly to neutrophils.…”

Localization of filipin-sterol complexes in cell membranes of eosinophils

“…Eosinophils may play an important role in the defense of the organism against certain parasites such as Schistosoma (Mahmoud et al 1975;Butterworth et al 1979), Trichinella (Grove et al 1977;Smithers et al 1977) and Trypanosoma (Sanderson and Jennifer 1978 ;Sanderson and De Souza 1979;Thorne et al 1979). In the case of large parasites the eosinophils attach and discharge the content of their specific granules on the surface of opsonized parasites.…”

Oxygen‐dependent microbicidal systems of phagocytes and host defense against intracellular protozoa

“…Antibody facilitates phagocytosis of T cruzi 142,451 and T dionisii [43], and may be important in extracellular killing of T cruzi by PMN [46,47]. MPO inhibitors (azide, cyanide, diethyldithiocarbamate) abolished the toxicity of PMN to L donovani [48] and T dionisii [30,44], supporting a role for MPO in mediating cidal activity. Electron microscopy demonstrated the release of granule material into the phagosome following ingestion of T cruzi trypomastigotes by rat neutrophils and eosinophils 1421.…”

“…Neutrophils, in which MPO comprises up to 5 % of the dry weight of the cell, effectively ingest and kill T gondii [41], L donovani promastigotes [34] and amastigotes [32], T cruzi trypomastigotes [42], and T dionisii epimastigotes and trypomastigotes [43,44]. Antibody facilitates phagocytosis of T cruzi 142,451 and T dionisii [43], and may be important in extracellular killing of T cruzi by PMN [46,47]. MPO inhibitors (azide, cyanide, diethyldithiocarbamate) abolished the toxicity of PMN to L donovani [48] and T dionisii [30,44], supporting a role for MPO in mediating cidal activity.…”