p0p 3-5 induce aggregate formation in vitro and rapid thrombocytopenia in vivo.
(A) Washed platelets (2 × 106) were incubated with 10 mg/mL of the indicated mAbs or without antibody (control) for 15 minutes at RT, followed by centrifugation at 1300g for 5 minutes. After resuspension of the pellets by vortexing for 5 seconds, the single platelet count in the samples was determined by flow cytometry. Results are shown as the mean ± SD for 3 independent experiments. (B) Normal female NMRI mice received 25 μg purified p0p 1,2,5 or F(ab)2-fragments of p0p 3,4 intravenously in 200 μL sterile PBS. The anti-GPIIIa mAb EDL1 was used as a control. Platelet counts were determined at the indicated times using an Improved Neubauer hemocytometer. Injection of a nonimmune IgG1 had no significant effect on the platelet count (not shown). Intact p0p 3,4 induced comparable thrombocytopenia as the F(ab)2-fragments (not shown). Results of platelet count are shown as the mean ± SD for groups of 3 mice. The experiment was repeated twice with comparable results.
