Effect of low temperature on the in vitro growth of Plasmodium falciparum.

The effect of low incubation temperature on synchronized cultures of Plasmodium falciparum was studied. Young trophozoites that were maintained at 28 degrees C matured slowly and invaded poorly. Growth seemed to arrest when parasites reached a maturation equivalent to 30 h, although they reestablished their growth normally when returned to 37 degrees C. On the other hand, 36-h synchronized parasites that were transferred to 28 degrees C completed their cell cycle with a 12-16 h delay, but without changes in the parasite as seen by light microscopy and without a diminution in the efficiency of the invasion or in the incorporation of 35S-methionine. These results might be useful for obtaining parasites at defined stages of development at the desired time.