Differential effect of immunoglobulin on the in vitro growth of several isolates of Plasmodium falciparum

Publisher Website
Google Scholar
Abstract
Ig isolated from the sera of [human] individuals living in a malarious area of Papua New Guinea was tested for an effect on the growth in vitro of 4 isolates of P. falciparum, 3 from Papua New Guinea and 1 from Thailand. The Papua New Guinea isolates were inhibited to the same degree by individual Ig preparations, and inhibition varied from 0-98% (assessed by a radioisotopic readout). Ig preparations which inhibited the Papua New Guinea isolates caused less inhibition of the Thai parasites. Biosynthetically labeled parasite proteins were analyzed by 2-dimensional gel electrophoresis, and differences were detected in the protein and antigenic composition of isolates which differed in their sensitivity to inhibitory immunoglobulin. Three acidic proteins (Mr [molecular ratio] 200,000, 150,000 and 65,000) were found only in the Papua New Guinea isolates. All Papua New Guinea isolates contained a high MW basic protein with an Mr of 220,000 (Pf220), but the corresponding protein of the same MW in the Thai isolate had a more acidic isoelectric point. Another isolate (from Africa) initially showed a degree of resistance to inhibition by Papua New Guinea Ig (although not to the same extent as the Thai parasite), but in later experiments, this isolate was susceptible to inhibition. During the course of this series of experiments, the antigenic composition of this (uncloned) isolate changed so that it became similar (but not identical) to the Papua New Guinea isolates.