Phagocytosis of Trypanosoma cruzi by Human Polymorphonuclear Leukocytes1
We wish to thank Dr. R. Docampo for his kindness in providing the culture forms of the parasite. This work was supported by grants from SECYT, CONICET, Cherny Foundation, and by the UNDP/World Bank WHO Special Training Programme for Research and Training in Tropical Diseases No. 790421.
ABSTRACT
Phagocytosis of culture forms of Trypanosoma cruzi was assayed by a radioisotopic method. Purified polymorphonuclear leukocytes (PMN) were mixed with 3H-uridine-labeled T. cruzi epimastigotes in the presence or absence of anti-T. cruzi antibodies. The reaction was stopped by adding N-ethyl-maleimide, and noningested parasites were lysed by complement. The percentage of radioactivity incorporated into the PMN pellet was recorded. The phagocytosis reaction was rapid, yielding maximum incorporation at 30 min at which point the radioactivity associated with the PMN cells decreased through release of the isotope to the supernatant. The degree of incorporation of radio-labeled parasites was a function of the effector/target cell ratio and the antibody concentration. The method is suitable for the quantitative determination of phagocytosis of T. cruzi by normal PMN.
