CULTURE OF MALARIA PARASITES IN 2 DIFFERENT RED-BLOOD-CELL POPULATIONS USING BIOTIN AND FLOW-CYTOMETRY

A novel culture system using biotin/streptavidin and now cytometry was developed to compare maturation and growth rates in Plasmodium falcip arum malaria parasites in two distinct red blood cell (RBC) population s, Biotin was used to label a selected RBC population which was then m ixed with another distinct unbiotinylated RBC population, P.falciparum -infected RBCs were used to initiate co-cultures followed over 2-3 sch izogonic growth cycles, Go-cultures were harvested and stained with st reptavidin-fluorescein isothiocyanate (FITC) followed by fixation and staining of parasite DNA, The combination of biotin/streptavidin-FITC and DNA fluorochrome enabled simultaneous now cytometric analysis of t he two different RBC populations and of the parasitemias in each RBC p opulation, we then used this system to study the in vitro susceptibili ty of RBCs from individuals with hemoglobin H (Hb H) disease to infect ion and growth of P.falciparum. Significant reduction in parasite mult iplication was found in Hb H RBCs as compared with that in normal RBCs . This novel malaria culture system offers two major innovations: a me thod to compare directly the relative ability of any two red blood cel l populations to support malaria parasite invasion and development und er identical conditions, and a critical reduction in the volume of blo od and reagents needed to assess parasite growth. The application of b iotin-labeled RBCs in the now cytometric analysis of parasite developm ent may offer new insights in studies of the relationship between RBC defects and susceptibility to malaria parasites. (C) 1996 Wiley-Liss, Inc.