Decreased growth of Plasmodium falciparum in red cells containing haemoglobin E, a role for oxidative stress, and a sero-epidemiological correlation.

The in vitro growth of Plasmodium falciparum in red cells containing haemoglobin E (HbE) was studied at oxygen concentration of 5 to 20%, with and without antioxidants. Under all conditions, parasite growth decreased as the concentration of HbE increased as compared with growth in red cells containing only HbA. The decreases were proportionately greatest at the highest oxygen concentration. The antioxidant vitamin C partially reversed the decreases in growth observed in HbE-containing cells at 20% oxygen. South-east Asian refugees with HbAE or HbEE had high antimalarial IFA titres, indicative of exposure to malaria more frequently than did refugees with HbAA. The decreased growth of P. falciparum in HbE-containing red cells may reduce the severity of malaria infections, conferring a survival advantage and thus increasing the numbers of individuals with HbE in local areas of South-east Asia with high incidences of malaria.