Analysis of a fibrin formation abnormality in a case of multiple myeloma.

Studies were performed to analyse the inhibitory effect of a myeloma globulin (IgG) on fibrin formation. This inhibitory activity was very intense and caused a severe bleeding disorder which proved fatal. The isolated myeloma globulin inhibited all three stages of fibrin formation: the proteolytic action of thrombin on fibrinogen, the aggregation of fibrin monomers and the stabilization of fibrin by cross-linkages in the gamma and alpha chains. Purified factor XIII, even in excess, previously activated by the addition of thrombin and calcium, did not correct this defect in cross linking. Our results suggest that this myeloma globulin induced a blockage of some receptors near the cross linking sites.