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Autocytotoxins during Rodent Malaria

1980; American Society of Parasitologists; Volume: 66; Issue: 5 Linguagem: Inglês

10.2307/3280685

1937-2345

Pyung-Rim Chung, Elaine Balsamo, Alan Gray, N. J. Rencricca, Robert M. Coleman,

vaccines and immunoinformatics approaches

served in the parasite samples at dilutions of 1:4 or less, and this represents approximately 0.5 ng equivalent E. coli endotoxin per milliliter of packed parasites. This low activity was also present at the same dilutions following exposure to heat, suggesting that the positive LAL test results resulted from heat stable endotoxin. The samples seeded with E. coli endotoxin showed no reduction in activity, thus excluding the possibility that an inhibitor was present in our preparations. The undiluted (1:1) control samples gave negative LAL results. There was no bacterial growth on any of the cultures. If P. falciparum malaria endotoxin activity were of the same order as P. berghei activity, then our preparation of greater than 1011 parasites/ml would be four log units greater than the mean number of parasites/ml in a human with a 1% parasitemia (5.4 x 107 infected red cells/ml). Griesman and Hornick (1979, Proc. Soc. Exp. Biol. Med. 131: 1154-1158) have shown that at least 1 ng of E. coli endotoxin/ kg of body weight is needed to produce a fever in man. Therefore, if our results are applicable to the response in man, the endotoxin activity equivalent/kg of body weight in a man with a 1% parasitemia would be approximately three log units below the threshold level (1 ng/kg) required for fever induction. From our studies, we conclude that the low endotoxin activity detected by the LAL assay in pure parasite preparations could not account for the fever seen in patients with malaria and that the endotoxin detected by others in plasma from malarious patients is probably derived from endogenous bacteria in the gut.