[Our experince with antiglobulin consumption (Dixon test) in the study of antibodies bound to platelets]

We measured the quantity of IgG bound to platelets (IgGP) by the antiglobulin consumption test (Dixon technic). In controls, the IgG level did not exceed 10 X 10(-15) g for one platelet. The amount of IgGP was often incraeased (more than 10 X 10(-l5) g) in some autoimmune diseases as lupus erythematosus, chronic lymphocytic leukemia and chronic active hepatitis. Among 26 patients presenting an idiopathic thrombocytopenic purpura (ITP) with a low number of platelets, 21 (77%) had a high titer of IgGP. In 6 ITP in remission, the IgGP titer was normal. After a review of the different technics detecting the IgG bound to platelets, we explain why we choose the antiglobulin consumption. This test is excellent for the research of anti-platelets auto-antibodies in ITP. Yet, the reaction remains negative in a minority of ITP. Several explanations are possible: low quantity of IgGP, presence of other anto-antibodies as IgM or IgA, cellular auto-immunity anti-platelets without antibodies, non immunologic ITP.