Human platelets at physiologic ratios do not inhibit in vitro replication of human strains of P falciparum. (A) Representative percent parasitemia measured by imaging flow cytometry over the course of 48 hours in cultures with platelets (open blue square) at 1:9 RBC ratio and without platelets (filled red circle). (B) Calculated replication inhibition of P falciparum replication in platelet cultures compared with no platelet controls (n = 6) at selected time points during the development of P falciparum parasites. (C) The percentage of uRBCs (red bars) ([#platelet:uRBC/#uRBCs]%) or iRBCs (blue bars) ([#platelet:iRBC/#iRBCs]%) with attached platelet over course of P falciparum development. (D) Percentage of all platelets that are unbound (green bars) ([#unboundplatelets/#platelets]%), bound to uRBCs (red bars) ([#platelet:uRBC/#platelets]%), or bound to iRBCs (blue bars) ([#platelet:iRBC/#platelets]%) during the course of P falciparum development. (E) Intensity of CD62P fluorescence on the surface of platelets after stimulation with selected doses of thrombin at selected time points of culture. (F) Calculated thrombin EC50 for platelet response at the selected time points of culture.