GP6 and autoimmune thrombocytopenic purpura: IgG antibodies against platelet glycoproteins, with an emphasis on GPIIb/IIIa and GPIbIX, are the most common types and GPIa/IIA and GPVI are the less common types of antibodies observed in ITP patients.[18–20] These antibodies bind to Fc receptors on macrophages, phagocytic cells that engulf and destroy foreign particles.