DETECTION OF HUMAN-SPECIFIC ANTI-LA(SSB) ANTIBODIES IN PATIENTS WITH RHEUMATOID-ARTHRITIS

Sera from anti-Ro(SSA) positive and negative patients with rheumatoid arthritis (RA) were compared with those from patients with primary Sjo gren's syndrome (pSS) and systemic lupus erythematosus (SLE) with rega rd to anti-La(SSB) antibodies. Several assays for anti-La(SSB) (RNA pr ecipitation, counterimmunoelectrophoresis, and immunoblotting) demonst rated the presence of such antibodies in selected anti-Ro(SSA) positiv e (10/19 in RA and 18/37 in pSS and SLE) but not in anti-Ro(SSA) negat ive sera. In agreement with previous reports, anti-La(SSB) antibodies from pSS and SLE patients uniformly reacted with various cellular extr acts used as sources of La(SSB) antigen, including extracts from human cultured cells (HeLa), calf thymus and rabbit thymus. In contrast, wh ite all 10 anti-La(SSB) sera from RA patients reacted with the human H eLa cell extracts, only three of them also reacted with calf and rabbi t thymus extracts. These results were further supported by the analysi s of a cohort of 70 consecutively selected sera (displaying monospecif ic anti-Ro(SSA) reactivity against calf thymus extract) from patients with various rheumatic disorders, where human-specific anti-La(SSB) we re detected in two out of the five of RA patients studied. (C) 1995 Ac ademic Press Limited