INHIBITION OF FIBRIN MONOMER POLYMERIZATION BY MYELOMA IMMUNOGLOBULIN

Myelomatosis was diagnosed in a 64 year old man on the basis of a seru m paraprotein band (type IgG lambda, 42g/l), plasma cell infiltration of bone marrow, and multiple lytic lesions evident on skull x ray pict ure. flood specimens taken into plain glass tubes showed bulky gelatin ous clot formation with minimal clot retraction. Coagulation tests wer e significantly abnormal with an increase in thrombin time, prothrombi n time, and reptilase time. The possibility that the paraprotein was i nterfering with fibrin production was investigated. The rate of fibrin monomer polymerisation (measured turbidometrically) was reduced in pa tient plasma compared with control plasma. Although purified fibrin mo nomer prepared from the patient's fibrinogen polymerised normally, the addition of purified paraprotein caused a dose dependent reduction in the rate of polymerisation. These results suggest that the paraprotei n was impairing fibrin formation by inhibiting fibrin monomer polymeri sation. After chemotherapy the paraprotein concentration decreased and the coagulation results returned to normal.