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Evidence for a neutrophil‐mediated protective response in malaria
Author(s) -
NNALUE NDUBISI A.,
FRIEDMAN M.J.
Publication year - 1988
Publication title -
parasite immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 75
eISSN - 1365-3024
pISSN - 0141-9838
DOI - 10.1111/j.1365-3024.1988.tb00202.x
Subject(s) - zymosan , parasite hosting , biology , hypoxanthine , plasmodium falciparum , superoxide dismutase , neutrophile , catalase , malaria , hemozoin , microbiology and biotechnology , immunology , giemsa stain , in vitro , biochemistry , enzyme , genetics , world wide web , computer science
Summary Zymosan‐activated and non‐activated human polymorphonuclear neutrophils (PMN) were added to in‐vitro cultures of the human malaria parasite Plasmodium falciparum in microtitre wells. Microscopic counting of parasites in Giemsa‐stained smears showed that at a PMN:RBC ratio of 1:150, the same as occurs in human malaria, parasites in wells with zymosan‐activatcd neutrophils were suppressed 65%. Determination of parasite nucleic acid synthesis by 3 H‐hypoxanthine incorporation showed that in wells with PMN:RBC ratio of 1:150 parasite viability was only 22% of control. Various oxygen scavengers were tested for ability to reverse the effects of activated neutrophils on parasite development. Superoxide dismutase (20 mg/ml) and catalase (50 mg/ml) had no effect; tryptophan protected the parasites to a moderate degree while histidine alleviated suppression of parasite development to the greatest extent. This suggests that singlet oxygen is the most effective neutrophil product in killing or suppressing the growth of parasites. We also observed that non‐activated neutrophils were activated by parasites and/or their products resulting in killing of newly‐released parasites.