Reduced complement activity in sera of patients with Waldenström's macroglobulinemia.

Whole serum complement activity and complement activity of C1, C2 and C3 were determined in the sera of 11 patients with Waldenström's macroglobulinemia. C1 and C3 levels were low in approximately 50% of the sera studied. Whole complement and C2 levels were low in three of the patients. Microzone electrophoresis revealed that in four of the 11 patients the paraprotein had relatively rapid γ or β mobility. Three of these patients had low whole serum C activity and low C2. No correlation between whole serum complement activity, immunoglobulin quantitative levels, cold agglutinins, cryoglobulins, anti-nuclear or anti-γ globulin antibodies could be made.