Presence of structurally abnormal molecules in monoclonal G immunoglobulins in human myelomas

Abstract

Monoclonal IgGs were isolated from the sera of 7 patients of multiple myeloma by ammonium sulphate precipitation and DEAE cellulose column chromatography. Analysis of incidence of class and light chain type showed that three monoclonal proteins were IgG1 type K, three IgG1 type L and one IgG2 type L. Biochemical and biophysical studies revealed the presence of subnormal molecules in 3 out of 7 cases. In one case, a rarely reported aggregated molecule of IgG having 10.32 S value was observed, while in another, a minor peak of a low molecular weight IgG of 4.83 S was observed and in the third case, the entire myeloma protein was of low S value 3.94. No antibody activity could be detected against a variety of antigens tested for, including common human commensal and pathogenic flora. Further, there was preponderance of lambda light chain monoclonal immunoglobulins. These observations lend support to the belief that the plasma cell malignancy in humans may result from genetic predilection rather than from chronic bacterial stimulation.