A Macroglobulin with Inhibitory Activity Against Coagulation Factor VIII

Deficiency of coagulation factor VIII occurred in a patient with a monoclonal gamma-M protein and characteristic features of Waldenström’s macroglobulinemia. The protein, found to contain lambda light chains, had specific activity against normal factor VIII that was reversible by reduction with 2-mercaptoethanol. Spontaneous correction of the clotting factor deficiency occurred during treatment. It is suggested that the macroglobulin in this patient removed or masked factor VIII by adsorption and that alteration of the protein in vitro by mercaptoethanol and in vivo by treatment removed this capacity.