Investigation of dose-dependent responses of monoclonal antibodies and IVIG. (A) Dose-dependent response experiments were performed with each antibody using 4 μg, 7 μg, and 10 μg per mouse, and 2 g/kg IVIG or control HSA. The data of a representative experiment from each group of antibodies (ie, JON1 and p0p5) are shown. The severity of thrombocytopenia increases following the escalating doses of both antibodies. Platelet counts are expressed as a percentage of the basal platelet count (700 × 109/L-1100 × 109/L) on day 1. n = 5; *P < .05. (B) Groups of BALB/c mice were injected with either IVIG (▪, •; 2g/kg) or HSA (□, ○) on day 1 and received 7 μg of either anti-GPIIbIIIa (JON1, JON2, JON3) or anti-GPIbα (p0p3, p0p4, p0p5) monoclonal antibody on day 2. n = 5; *P < .05. (C) BALB/c mice were injected with either IVIG (▪; 4g/kg) or HSA (□) on day 1 and received 7 μg of either anti-GPIIbIIIa (JON1, JON2, JON3) or anti-GPIbα (p0p3, p0p4, p0p5) monoclonal antibody on day 2. Percent decreases in platelet counts 24 hours after antiplatelet antibody injection were compared. n = 5; *P < .05. (D) IVIG-treated mice injected with JON3 mAb showed significant improvement in the attenuation of thrombocytopenia with escalating doses of IVIG (1 g/kg, 2 g/kg, and 4 g/kg). Platelet counts on both day 3 and day 4 at each dose of IVIG are compared with normal platelet counts (100%) on day 2, prior to JON3 injection. n = 5.
