Clinical relevance of antikeratin antibodies in rheumatoid arthritis.

Antikeratin antibodies (AKA) were found in 38 out of 96 patients with rheumatoid arthritis (RA); they appeared to be quite characteristic to this disease. There was a very low incidence of AKA positivity in the control groups, i.e., 1 out of 62 healthy subjects and 4 out of 158 other patients. With regard to the sensitivity of the test as a diagnostic tool, AKA was found to be weaker than the rheumatoid factor (RF) and the antiperinuclear factor (APF), whereas the specificity was much better than APF and RF. A clear correlation was shown between the titres of AKA and APF (p less than 0.001) and also between AKA levels and inflammation (p less than 0.02).