MULTIPLE-MYELOMA AND MONOCLONAL IGA WITH ANTI-ACTIN REACTIVITY

  • 1 January 1977
    • journal article
    • research article
    • Vol. 30  (3) , 379-383
Abstract
Serum containing a monoclonal Ig[immunoglobulin]A protein from a patient with multiple myeloma gave intense immunofluorescent staining of smooth muscle fibers and the striations of skeletal muscle, cardiac muscle and thymic myoid cells. It also gave a weaker reaction with hepatocytes in a ''polygonal'' pattern, and with renal glomeruli in a diffuse pattern. In cultured fibroblasts, the serum stained long, parallel cytoplasmic filaments. Specificity of the staining reactions for actin was established by their prevention on serum absorption with skeletal muscle actin, but not by skeletal muscle myosin, tropomyosin or troponin. Specificity was also shown through demonstration that eluates obtained by acid dissociation of the serum-actin precipitates gave the same staining reactions as the original serum. Localization of the anti-actin reactivity to the monoclonal IgA protein was established by the the observation that the same staining reactions were obtained with a monospecific IgA conjugate, with the eluate derived from the .gamma.-globulin band of a serum electrophoretic strip, and with a purified euglobulin (IgA) fraction; also, the eluates obtained by acid dissociation of the serum actin precipitates contained monoclonal IgA.