Late depletion of platelets with anti-CD41 mAb injection does not protect against the development of severe malaria, whereas early treatment does. Blood (2 μL) was obtained from groups of mice injected with anti-CD41 mAb on either day 4, 5, or 6 of infection (not protected), from a group of mice injected with anti-CD41 mAb on day 1 (protected), and from a group of mice injected with PBS on day 4 (unprotected control). The number of CD41⁺CD61⁺ and CD41^–CD61^– platelets were determined by flow cytometry. The average number plus or minus SD of cells is shown (x axis). ▪ indicates CD41⁺CD61⁺; ▨, CD41^–CD61^–. Few (< 0.1%) if any single positive cells (CD41⁺CD61^– or CD41^–CD61⁺) were detected.