Inhibition of Platelet-Mediated Clumping of IRBCs by Soluble gC1qR/HABP1 and CD36-Fc

<p>Parasite cultures in trophozoite and schizont stages were allowed to form clumps in the presence of PRP. Parasites were stained with acridine orange and the clumping frequency was determined by scoring the frequency of IRBCs found in clumps. Approximately 2,000 to 3,000 IRBCs were scored. Parasite cultures were pre-incubated with recombinant gC1qR/HABP1 or CD36-Fc at different concentrations prior to use in clumping assays to test their ability to inhibit clumping. Clumping frequency in the presence of gC1qR/HABP1 or CD36-Fc is expressed as relative clumping compared to clumping in the presence of PRP alone. Data represent the average (± standard error) of two independent experiments. Each assay was performed in duplicate. (A) IGH-CR14, (B) 3D7, (C) IGH-CR14−, (D) 3D7−, (E) IGH-CR14+, (F) 3D7+.</p>