The Effect of Thalassemic Serum on Plasmodium Falciparum Growth in Vitro

Abstract

Thalassemia and malaria are present at high frequency in tropic and sub-tropic regions. Impaired growth of Plasmodium falciparum has been demonstrated in vitro in both α-and β- thalasemic erythrocytes. In this study, we investigated the effects of thalassemic sera on Plasmodium falciparum developement including 5 α-thalasemia1/α-thalasemia2 (HbH) sera, 4 α-thalasemia 1/hemoglobin Constant Springs (HbH/HbCS) sera and 7 β-thalassemia/ HbE sera compared to 7 normal sera. Study on malarial growth in medium containing 10% various sera for 4 days revealed that HbH and β-thalasemia/ HbE sera was significantly inhibited (p<0.05, by Mann-Whitney U-test) the parasite growth comparing to normal serum. Mean percentages of the parasites grown in HbH (2.24+0.75%) and β-thalassemia/ HbE (1.69+0.97%) sera were about 2 times less than that in normal serum (4.55+2.40%). The mean parasitemia cultured in HbH/HbCS serum (2.38+1.54%) was also lower than that in normal serum but it was non-significantly different. Investigation on stage changing of the parasite among the starting, 1st, 2nd, 3rd and 4th day showed that all thalassemic sera retarded the parasite maturation from stage to stage. Decrease in percent ring stage production was observed in culture with HbH/HbCS and β-thalassemia/HbE sera. This might be resulted from reduction of merozoite population in mature schizont or failure of re-invasion of the merozoite. Therefore, not only cellular factors but also serum factors of thalassemic patients inhibited P. falciparum development which may be related to the protective mechanism of thalassemic patients from P. falciparum infection.