Factor VIII complex in myelomatosis and related disorders

The behaviour of the factor VIII/von Willebrand factor complex (VIII:C, VIIIR:Ag and VIIIR:RCof) was investigated in 23 patients with secretory myeloma, in 2 patients with non-secretory myeloma and in 5 patients with macroglobulinemia. In most patients (21 of 25 patients with plasma cell myeloma and 2 of 5 patients with macroglobulinemia) VIIIR:Ag was increased usually without corresponding increases in VIII:C and VIIIR:RCof. There was no correlation between the VIIIR:Ag levels and paraprotein Ig type or level nor with the presence or the absence of Bence Jones proteins in serum and urine. Furthermore, increased levels of VIIIR:Ag were found in patients with non-secretory myeloma. In general, VIIIR:Ag was higher in patients with extensive bone lesions and there was a significant correlation between cell mass and the VIIIR:Ag level. The crossed-immunoelectrophoresis of plasmas with discrepant VIIIR:Ag and VIIIR:RCof showed variation from the normal pattern.