Turnover of Labeled Normal Gamma Globulin in Multiple Myeloma*

Aberrations of protein metabolism in multiple myeloma have been studied by a number of in-vestigators (1-6) to ascertain whether the globu-lins in the blood consist of excesses of normal globulins or of chemically abnormal globulins, or both. Such research has been directed toward determining whether characteristic protein ab-normalities could be distinguished by 1) sepa-ration of the serum proteins with identification of their physicochemical properties by using the Tiselius electrophoresis apparatus and the analyti-cal ultracentrifuge; 2) certain structural relation-ships indicated by the amino end-group method; 3) immunochemical procedures; and 4) detection of formation of abnormal protein by administering to the patient isotopically labeled amino acids, the tracers being the stable isotopes N15 and C13 or radioactive carbon, C14. By use of such experi-mental methods it has been reported that at least some, if not all, of the quantitatively exces-sive globulins produced in this disease are ab-normal. Our approach to the investigation of certain fundamental aspects of protein metabolism in this disease has been concerned with the patients turnover of globulins. Data are being presented which were obtained by determining the biologi-cal half-life of gamma globulin fractionated from normal individuals, labeled with I131 and injected into ten patients with clinically proven multiple myeloma. A subsequent report will be devoted to the findings when the source of the fractionated gamma globulin was from patients with multiple myeloma. The latter study permitted observa-tions on the half-life of labeled autologous and homologous preparations in this disease. The electrophoretic pattern of the serum of each