Impairment of Plasmodium falciparum growth in thalassemic red blood cells: further evidence by using biotin labeling and flow cytometry.

Certain red blood cell (RBC) disorders, including thalassemia, have been associated with an innate protection against malaria infection. However, many in vitro correlative studies have been inconclusive. To better understand the relationship between human RBCs with thalassemia hemoglobinopathies and susceptibility to in vitro infection, we used an in vitro coculture system that involved biotin labeling and flow cytometry to study the ability of normal and variant RBC populations in supporting the growth of Plasmodium falciparum malaria parasites. Results showed that both normal and thalassemic RBCs were susceptible to P falciparum invasion, but the parasite multiplication rates were significantly reduced in the thalassemic RBC populations. The growth inhibition was especially marked in RBCs from alpha-thalassemia patients (both alpha-thalassemia1/alpha-thalassemia2 and alpha-thalassemia1 heterozygote). Our observations support the contention that thalassemia confers protection against malaria and may explain why it is more prevalent in malaria endemic areas.