Diagnostic value of antikeratin antibodies in rheumatoid arthritis.

The value of testing for antikeratin antibodies (AKA) in the diagnosis of rheumatic diseases was investigated. AKA were found in the serum of 71 (54%) of 131 patients with rheumatoid arthritis (RA) (including 10 rheumatoid factor (RF) negative individuals) but only in 7 (2%) of 266 patients with non-RA rheumatic diseases, in 2 (3%) of 69 patients with miscellaneous immunological diseases and in one of 100 healthy controls. AKA positivity in RA patients correlated with their age and the presence of RF, antinuclear antibodies, subcutaneous nodules, as well as the extent and severity of systemic disease manifestations. Our study suggests that determination of AKA would be of value in the assessment of patients suspected of having RA.