SERA OF PATIENTS WITH RHEUMATOID-ARTHRITIS CONTAIN ANTIBODIES TO RECOMBINANT HUMAN T-LYMPHOTROPHIC VIRUS TYPE I II ENVELOPE GLYCOPROTEIN P21/

A possible retroviral etiology for rheumatoid arthritis (RA) has been raised by results of recent studies. Therefore, we examined sera of pa tients with RA, including those with coexisting Felty's syndrome or le ukemia of large granular lymphocytes, for the presence of antibodies t o retroviral proteins of human T-lymphotrophic virus type I and type I I (HTLV-I/II). Reactivity to recombinant HTLV-I envelope protein rpg21 alone was the primary pattern observed. Twenty-five percent of RA ser a, 28% of Felty's syndrome sera, and 30% of large granular lymphocyte leukemia/RA sera reacted with rgp21, each significantly more than the 8% of normal sera (P < 0.01). Removing rheumatoid factor did not aboli sh reactivity with rgp21 in any of six RA sera tested. Immunoreactivit y to the authentic viral protein was confirmed by using purified rgp21 that was cleaved by CNBr to remove the bacterial fusion peptide, or b y blocking sera with a synthetic peptide corresponding to the fusion p eptide. Only one serum, from a patient with RA, showed definite eviden ce for prior infection with prototypic HTLV-II. These data indicate th at 25% of RA sera have IgG antibodies to recombinant HTLV-I envelope p rotein rgp21, which is highly homologous to envelope protein gp21 of H TLV-II. These findings provide potentially novel clues regarding the p athogenesis of RA. (C) 1996 Academic Press, Inc.