CRITHIDIA-FASCICULATA AS FEEDER CELLS FOR MALARIA PARASITES

Crithidia fasciculata was used to replace murine peritoneal wash cells as feeder cells for the adaptation of Plasmodium falciparum isolates to continuous culture in vitro, thus avoiding the need to sacrifice an imals. Fourteen of 17 malaria parasite isolates in one study, and 12 o f 12 isolates in a second study, were successfully adapted to continuo us culture in the presence of C. fasciculata, while only 5 of 17 paral lel control isolates in the first study, and 2 of 12 isolates in the s econd study, were adapted in the absence of any feeder cells. Biochemi cal assays were performed to investigate various hypotheses put forwar d to explain the mode of action of feeder cells. No effect of C. fasci culata feeder cells was observed on lactate removal, osmotic pressure, or glucose or amino acid content of the malaria culture media. This f eeder cell system was shown to reduce the pH of the malaria culture me dium. Neither this feeder system nor another system, murine peritoneal macrophages, had any effect on the cysteine content of the culture me dium. C. fasciculata was shown to reduce the redox potential of the cu lture medium, as were other malaria growth enhancers including cystein e and glutathione. This effect on the redox potential of the culture m edium is proposed to be a possible mode of action for the feeder cell systems studied. (C) 1995 Academic Press, Inc.