SEPARATION OF 2 MOLECULAR-SPECIES OF THE SM ANTIGEN BY AFFINITY-CHROMATOGRAPHY WITH MURINE MONOCLONAL AND HUMAN ANTI-NUCLEAR AUTOANTIBODIES

  • 1 January 1983
    • journal article
    • research article
    • Vol. 51  (1) , 8-16
Abstract
Nuclear ribonuclear protein (nRNP) and Sm were extracted from a 30-60% ammonium sulphate fraction of rabbit thymus extract by affinity chromatography. Immunoadsorbent columns were prepared from IgG extracted from an anti-nRNP serum, an anti-Sm serum and 2 monoclonal autoantibodies derived from a MRL/lpr mouse. All 4 immunoadsorbents isolated both nRNP and Sm antigens indicating that they exist as the nRNP/Sm complex. A species of Sm which did not bind to the anti-nRNP column and which was subsequently purified with the anti-Sm column was termed free Sm. The Sm in the complex and free Sm were immunologically identical on immunodiffusion and gave similar polypeptide bands on polyacrylamide gel electrophoresis. They differed in that complexed Sm was sensitive to heat and RNAase. These studies provide direct evidence of a physical association between the nRNP and Sm antigens and indicate an additional molecular species of Sm whose resistance to RNAase may be due to different associated RNA species.

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