Immunopathology of rheumatoid arthritis. Antikeratin antibodies precede the clinical disease.
OBJECTIVE: We sought to determine whether circulating antikeratin antibodies (AKA) precede the onset of rheumatoid arthritis (RA). METHODS: By matching the registers of 2 previous population studies with the registry of patients receiving antirheumatic drugs several years later, pre-illness serum specimens could be obtained from 39 individuals who subsequently developed RA. AKA were assayed with the standard indirect immunofluorescence technique. RESULTS: Ten of 39 serum specimens from individuals who subsequently developed seropositive RA, and 1 of 15 sera from individuals who developed seronegative RA, were positive for IgG-class AKA by immunofluorescence assay. The AKA-positive sera were also positive for rheumatoid factors. CONCLUSION: The findings focus attention on the role of pre-illness immunologic events in the pathogenesis of RA.