Maternal autoimmune thrombocytopenia and the newborn.

That a humoral factor was the causative agent in idiopathic thrombocytopenic purpura was suggested nearly 30 years ago after the observation that mothers with the disease often give birth to children who develop transient thrombocytopenia.1 Maternal platelet autoantibodies were presumed to pass into the fetal circulation. With present techniques2 3 platelet autoantibodies are detectable in most patients with idiopathic thrombocytopenic purpura. We have therefore tried to confirm the passage of autoantibodies through the placental barrier and determine their immunochemical characteristics. We used specific antiglobulin reagents labelled with fluorescein isothiocyanate.