Thrombocytopenia, induced by repeated subcutaneous administration of anti-GPIbα antibody 5A7. (A) The antibody 5A7 (0.08 mg/kg) was injected subcutaneously (s.c.) every 3 days. Blood platelet counts were measured before and at the indicated time points after antibody injection. (B) Plasma TPO level was measured by enzyme-linked immunosorbent assay. (C) Immunostaining analysis of organs harvested on day 8 performed as described for the corresponding images in Figure 1. Bars represent 100 µm. (D) Immunostained BM sections were visualized by fluorescence microscopy (top) and confocal microscopy (bottom). Bars represent 100 μm (upper panels) and 10 μm (lower panels). (E) Plasma samples collected from mice treated with single dose (2 mg/kg) of IV 5A7 injection (left), and 3 doses of subcutaneous injection (0.08 mg/kg each) were analyzed by enzyme-linked immunosorbent assay to measure plasma concentration of administered 5A7.