ANTIBODY RECOGNITION OF THE RECOMBINANT HUMAN NUCLEAR ANTIGENS RNP 70-KD, SS-A, SS-B, SM-B AND SM-D BY AUTOIMMUNE SERA

Five human nuclear antigens, RNP 70 kD, SS-A, SS-B, Sm-B and Sm-D, wer e produced in E. coli using the expression vector pSEM. cDNAs encoding these antigens were ligated to a truncated lacZ' gene of the vector a nd the beta-galactosidase fusion proteins were efficiently expressed a s intracellular inclusion bodies after isopropyl-beta-thiogalactopyran oside induction. The antibody reactivities of these fusion proteins we re evaluated by Western blot and by ELISA employing panel sera from pa tients with autoimmune diseases such as systemic lupus erythematosus, Sjogren's syndrome or mixed connective tissue disease. The three fusio n proteins, RNP 70 kD, SS-B, and Sm-B, showed good reactivities in bot h systems, whereas the other two fusion proteins, SS-A and Sm-D, showe d poor and no reactivity in both systems, respectively. It can be conc luded that RNP 70 kD, SS-B and Sm-B recombinant antigens are useful re agents for the differential diagnosis of the autoimmune diseases.