IgM anticoagulant with acquired abnormalities in factor VIII.

The effects of an IgM lupus anticoagulant on coagulation tests and factor VIII related antigen (FVIIR:Ag) were investigated on a 62 year old man with lymphocytic lymphoma. He experienced no abnormal bleeding despite a prothrombin time of 29 seconds, PTT 84 seconds and inhibition of multiple coagulation factors. One course of chemotherapy induced a clinical response, normalization of coagulation studies and a rapid fall in IgM from 1120 to less than 30 mg%. Studies revealed a monoclonal IgM, immediate-acting lupus anticoagulant. This IgM could not be shown to affect normal FVIIIR:Ag but the patient's FVIIIR:Ag was grossly abnormal on crossed immunoelectrophoresis with a normal and a rapidly-migrating peak. The anodal component disappeared after chemotherapy. These studies suggest that the anticoagulant was temporally related to but did not cause the abnormality in FVIIIR:Ag. Such antibodies may occasionally serve as disease markers and may point out the disparity between coagulation tests and hemostasis.