IDENTIFICATION OF PROTEIN DISULFIDE-ISOMERASE AND CALRETICULIN AS AUTOIMMUNE ANTIGENS IN LEC STRAIN OF RATS

Long Evans Cinnamon (LEC) rats, showing spontaneous hereditary hepatit is and hepatic carcinoma, were found to possess autoimmune antibodies to liver microsomal proteins, particularly to proteins with the molecu lar weight of 56kD and 55kD. The antibodies occurred in association wi th acute lethal hepatitis in the LEC rats in our previous study. Two-d imensional immunoblot analysis of the antigenic proteins revealed that the 56kDa and 55kDa proteins showed 4.2 and 4.0 pi values and were es timated to be protein disulfide isomerase (PDI) and calreticulin, resp ectively, from NH2-terminal amino acid sequence analysis. These protei ns were further identified by immunoblot analyses using purified prote ins and specific antibodies. PDI was a major autoimmune antigenic prot ein.