Idiotype‐bearing and antigen‐binding receptors produced by blood T lymphocytes in a case of human myeloma

Abstract

Abstract Twenty‐five to 30 % of blood lymphocytes from a myeloma patient with an IgGl( k ) protein with antibody activity to horse α 2 ‐macroglobulin (α2M) reacted with purified IgG from a rabbit antiserum to the idiotypic determinants of this protein. A small proportion of these idiotype‐bearing lymphocytes were IgG‐bearing B cells, but most of them were T cells. Several experiments demonstrated the actual synthesis of the idiotypic structures carried by the T lymphocytes. All idiotype‐bearing lymphocytes bound horse α2M, and the structures that bore the idiotype and bound the antigen were shown to completely cocap. After biosynthetic labeling with 14 C‐labeled amino acids, immunoprecipitation and sodium dodecyl sulfate gel electrophoresis, the anti‐idiotypic serum and the α2M antigen were found to react with the same molecules. Preliminary data on the size of these antigen‐binding T lymphocyte‐derived molecules are in accord with those of Binz and Wigzell ( Scand. J. Immunol. 1976. 5: 559) in the rat. The finding in this patient with multiple myeloma of a homogeneous and possibly malignant population of T lymphocytes, synthesizing identical antigen receptors which share idiotypic (but not isotypic) determinants of the immunoglobulin molecule produced by the malignant B cell clone, therefore confirms in man the results of several recent studies in other mammalian species.