Influence of human chorionic gonadotropin (hCG) on in vitro growth of Plasmodium falciparum.
BACKGROUND
During pregnancy, women are more susceptible to Plasmodium falciparum infections and frequently have a higher parasitaemia than non-pregnant women. Several mechanisms are responsible for their increased susceptibility, including down-modulation of immune responses that aid in parasite clearance and sequestration of infected erythrocytes in the placenta. Early in pregnancy, a third mechanism may contribute to higher parasitaemia, since it has been reported that addition of human chorionic gonadotropin (hCG) to in vitro cultures of the NF54-strain of P. falciparum results in increased parasite growth rates. The goal of this study was to further examine the effect of hCG on P. falciparum growth.


METHODS
The NF54-3D7, FVO and 7G8 strains of P. falciparum were cultured in vitro with various physiological concentrations of hCG purchased from three sources. Infected erythrocytes were also co-cultured with a human cell line that naturally secretes hCG.


RESULTS
Results from 14 experiments using different combinations of parasite strains and concentrations of hCG from different sources, as well as the co-culture studies, failed to provide convincing evidence that hCG enhances parasite growth in vitro.


CONCLUSIONS
Based on these data, it seems unlikely that hCG has a direct effect on the rate of parasite growth early in pregnancy.
Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A Burns School of Medicine, University of Hawaii, 651 Ilalo Street, Honolulu, HI 96813, USA. clintonp@hawaii.edu
Clinton K
CK
Pong
Audrey Davidson
AD
Thévenon
James Ainong
JA
Zhou
Diane Wallace
DW
Taylor
D000704:Analysis of Variance; D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology; D006063:Chorionic Gonadotropin / Q000276:immunology / Q000494:pharmacology*; D018997:Chorionic Gonadotropin, beta Subunit, Human; D018920:Coculture Techniques; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D018512:Parasitemia / Q000276:immunology*; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000254:growth & development* / Q000276:immunology; D015800:Protozoan Proteins / Q000276:immunology
D000953:Antigens, Protozoan; D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D015800:Protozoan Proteins