Antibody studies of factor VIII inhibitor in a case with Waldenstrom's macroglobulinemia

We report a case of Waldenstrom's macroglobulinemia with prominent bleeding tendency; laboratory investigation revealed an elevated activated partial thromboplastin time. Further laboratory evaluation showed circulating facto r VIII anticoagulant, deemed polyclonal IgG, with a titer of 700 Bethesda U nits/ml, The factor VIII inactivation kinetics of the patient plasma were i dentical to those of a type II inhibitor, and the inhibitor was found to re cognize the A2 domain of the factor VIII heavy chain. Apparently, paraprote in is not always the cause of reduced activity of coagulation factors in ne oplastic dysproteinemias, Am. J. Hematol, 63: 145-148, 2000. (C) 2000 Wiley -Liss, Inc.