[IgA RIPA inhibitor in a case of acquired von Willebrand syndrome].

Acquired inhibitor of von Willebrand factor-platelet interaction occurring in a 57 year-old female has been partially characterized. She had no personal or familial bleeding tendencies, but presented a subcutaneous hematoma of recent origin. She was diagnosed as having an acquired von Willebrand syndrome because she had low levels of FVIII complex in plasma, with platelet adhesiveness to glassbeads and RIPA decreased. This inhibitor was classified as an IgA immunoglobulin, and had no activity against any component of FVIII complex. The purified IgA by the chromatographic technology interacted with normal platelets to inhibit RIPA. Following 1-deamino-8-D-arginine vasopressin (DDAVP) infusion, she had higher immediate rise in all components of FVIII complex in plasma, with no rapid decline. Plasma von Willebrand factor (vWF) multimers analyzed by 1.5% SDS-AGE technology revealed to be identical with those of normal plasma. These studies suggest that the abnormality of ristocetin-induced vWF-platelet interaction by IgA RIPA inhibitor and the reduction of all vWF multimers (like type IA von Willebrand disease) may have a relationship with the pathogenesis of bleeding diathesis in this case.