Background: Cytoadherence of Plasmodium falciparum- infected erythrocytes to host cells is an im-portant trait for parasite survival and has a major role in pathology of malaria disease. Infections with P. falciparum usually consist of several subpopulations of parasites with different adhesive prop-erties. This study aimed to compare relative sizes of various binding subpopulations of different P. falciparum isolates. It also investigated the adhesive phenotype of a laboratory P. falciparum line, A4, using different binding techniques.
Methods: Seven different P. falciparum isolates (ITG, A4, 3D7 and four field isolates) were cultivated to late trophozoite and schizont and then cytoadherence to cell differentiation 36 (CD36), intercellu-lar cell adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule (V-CAM) and E-selectin were examined. The relative binding sizes of parasite subpopulations to human receptors were measured by mini-column cytoadherence method. The adhesion phenotype of P. falciparum-A4 line was evaluated by in vitro static, flow-based and mini-column binding assays.
Results: The relative binding size of ITG, A4 and 3D7 clones to a column made with CHO/ICAM-1 was 68%, 54% and 0%, respectively. The relative binding sizes of these lines to CHO/CD36 were 59.7%, 28.7% and 0%, respectively. Different field isolates had variable sizes of respective CD36 and ICAM1-binding subpopulations. A4 line had five different subpopulations each with different binding sizes.
Conclusion: This study provided further evidence that P. falciparum isolates have different binding subpopulations sizes in an infection. Furthermore, measurement of ICAM-1 or CD36 binding sub-populations may practical to study the cytoadherence phenotypes of P. falciparum field isolates at the molecular level.