[Anti-keratin antibodies. A marker of progressive rheumatoid arthritis].

Anti-keratin antibodies have been detected by indirect immunofluorescence on rats esophageal sections in 122 rheumatoid polyarthritis, 100 seropositive and 22 seronegative. The frequency of anti-keratin antibodies is 58 p. cent in seropositive rheumatoid polyarthritis and 41 p. cent in seronegative rheumatoid polyarthritis. Anti-keratin antibodies have a very good specificity (96 p. cent) for rheumatoid polyarthritis since in a group of 105 controls, only 4 sera were found to have a low titre of anti-keratin antibodies (1 ankylosing spondyloarthritis, 2 sclerodermis, 1 healthy subject). The mean titre of antikeratin antibodies is higher in seropositive rheumatoid polyarthritis than in seronegative rheumatoid polyarthritis. Within seropositive rheumatoid polyarthritis, the titre of anti-keratin antibodies is correlated with the titre of rheumatoid factors determined by the latex test (r' = 0.464, p less than 0.01). The presence of anti-keratin antibodies is correlated with the degree of functional handicap evaluated by the functional index of Steinbrocker (p less than 0.02) and with the biological evolution evaluated by the sedimentation rate (p less than 0.001). No correlation was found with accidents of intolerance to fundamental treatments (gold salts, D-penicillamine), especially skin diseases. Anti-keratin antibodies represent therefore a diagnostic marker for seropositive rheumatoid polyarthritis as well as seronegative ones and an evolutive marker of seropositive rheumatoid polyarthritis.