Myeloma-like immune globulins present themselves as narrow bands upon paper electrophoresis, and usually show a characteristic appearance in immunoelectrophoresis. Two antigenically different groups of myeloma proteins have been described: groups I and II. Recently, 60% of normal γ-globulin, throughout the mobility range of γ-globulin, has been shown to possess the antigen characteristic for group I, and 30% that for group II myeloma.
Occurrence of myeloma-like proteins in the serum is not restricted to multiple myeloma. They may also be seen with other tumors, such as reticulum cell sarcoma, and various carcinomas. In addition, Sonnet and Milhaux have reported on the frequent occurrence of myeloma-like ("monoclonal") γ-globulins in the serum of adult Bantus with different diseases.
When large amounts of a myeloma protein are present in the serum, it may be found in a much lower concentration in the spinal fluid.