T-cell epitopes on the 70-kDa protein of the (U1)RNP complex in autoimmune rheumatologic disorders

Abstract

High-titre IgG antibodies against the immunodominant 70-kDa protein of the (U1)ribonucleoprotein (RNP) complex are present in virtually 100% of patients with mixed connective tissue disease (MCTD), and less commonly in a variety of other autoimmune rheumatic diseases. As T-cell 'help' is assumed to be required for this potentially pathogenic form of immune response, investigations to define T-cell epitopes on the 70-kDa protein were undertaken. In prior studies we expressed the 70-kDa protein and a number of its fragments, spanning most of the molecule, as recombinant fusion proteins using the pGEX expression-vector system. These fusion proteins were used as antigens in the epitope mapping s..