Immunologic thrombcytopenic purpura (ITP) affects both children and adults. The incidence is estimated in adults about 1,6/100 000/per year. Chronic and relapsing forms of the disease that represent 70% of adult cases are associated with impairment of quality of life related to treatments side effects and bleeding. ITP is secondary to the destruction of circulating platelets through an auto-immune process and to a decrease of platelet production in bone marrow. Auto antibodies are usually directed against epitopes of the GPIIb/IIIa, expressed by platelets. The destruction of the platelets seems to occur mainly in the spleen through antibody dependent cytotoxicity. Both macrophages and cytotoxic T lymphocytes subsets participate to the platelet destruction through the CD16, the low affinity receptor for the Fc of IgG. Thus the CD16 "pathway" is a target for treatments in ITP as for example intravenous immunoglobulins and more recently inhibitors of the syk kinase.