Effect of serum derived blocking factor (SDBF) on platelet associated-IgG.

We analyzed the effect of an unknown factor, which derived from serum, on platelet associated IgG (PA-IgG) and we established the novel immunofluorescence method to measure the level of PA-IgG. Blood samples were obtained from 20 patients with idiopathic thrombocytopenic purpura (ITP). After the treatment of platelets with neuraminidase, the value of PA-IgG positive platelets (%PA-IgG) were significantly increased in patients with ITP, but not in controls.