ANTIGENIC RELATIONSHIPS OF BENCE JONES PROTEINS, MYELOMA GLOBULINS, AND NORMAL HUMAN γ-GLOBULIN

By means of immunodiffusion and immunoelectrophoresis study has been made of antigenic relationships of Bence Jones proteins, and the three classes of normal and pathological immunoglobulins, 7S γ, β(2A), and β(2M). All thirty-nine Bence Jones proteins studied could be classified into either one of two distinct antigenic types, A or B. Both types are related to the immunoelectrophoretically slow (S) fragment of a papain digest of normal γ-globulin; B is related more closely than A, but neither has antigenic determinants in common with the fast (F) fragment. The 7S γ myeloma globulins were either immunological type I or II. The papain digests of these proteins produced the S and F precipitin lines in immunoelectrophoresis but multiple bands in starch gel electrophoresis, especially in the F region. The S fraction of type I myeloma globulins is antigenically similar to Bence Jones protein of type B, and the S component of type II myeloma globulins has antigenic determinants in common with type A Bence Jones protein. Correspondingly, myeloma patients with type I globulins and proteinuria usually excrete type B Bence Jones proteins, whereas patients with type II excrete type A proteins. The F fragment is the part common to normal 7S γ-globulin and types I and II myeloma globulins but is absent in β(2A) and β(2M) pathological globulins and in both types of Bence Jones proteins. Papain digests of β(2A) myeloma globulins produced a single precipitin line in immunoelectrophoresis. β(2A) myeloma globulins appeared to have two antigenic units, one in common with type B Bence Jones protein and normal γ-globulin, and another specific to β(2A). The β(2A) myeloma patients excreted type B Bence Jones protein. The papain digest of a macroglobulin produced two precipitin lines, the faster of which had antigenic determinants in common with type B Bence Jones protein, the slower seemed specific for the macroglobulin. Five serum micromolecular globulins proved to be either type A or B Bence Jones proteins. From the above results, an antigenic map was constructed showing which determinants are shared and which are specific for normal 7S γ-globulin, types I and II myeloma globulins, β(2A) myeloma globulins, a macroglobulin, and types A and B Bence Jones proteins.