Antibodies to the Epstein-Barr virus nuclear antigen and to rheumatoid arthritis nuclear antigen identify the same polypeptide.

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Abstract
Patients with seropositive rheumatoid arthritis (RA) have elevated titers of precipitating antibody toward an antigen designated RA nuclear antigen (RANA). Anti-RANA reactivity was associated with prior Epstein-Barr virus (EBV) infection. Using the protein blot technique, a MW 80,000 polypeptide that is reactive with anti-RANA-containing sera was identified in extracts of WI-L2, an EBV+ nonproducer B lymphoblast line. This same polypeptide can be recovered from RANA precipitin bands. The MW 80,000 polypeptide appears to be EBV-associated, as a homologous antigen was detected in 2 other EBV+ cell lines, Daudi and Raji, but was not present in 3 EBV- human cell lines tested, [human cervical carcinoma] HeLa, and [human lymphoblastoid] BJAB and Ramos. Anti-RANA antibodies and antibodies reactive with the MW 80,000 polypeptide also appear coincidently in the sera of individuals exhibiting an EBV infection (infectious mononucleosis). Further analysis of the RANA-associated MW 80,000 polypeptide suggested its identity with the previously recognized EBV-associated nuclear antigen designated EBNA. The MW 80,000 antigen shares with EBNA the properties of being a heat-stable, DNA binding protein. EBNA is traditionally assayed by a complement fixation reaction and anti-MW 80,000 antibodies were shown to be reactive when a complement fixation assay was used in the immunoblot. When the MW 80,000 antigen was used to absorb an anti-RANA/anti-EBNA serum, both antibodies were reduced.