Anti-keratin antibodies in patients with juvenile idiopathic arthritis

OBJECTIVE: We discuss the presence of anti-keratin antibodies (AKA) of the IgG class in patients with defined juvenile idiopathic arthritis (JIA). METHODS: An indirect immunofluorescence test with rat oesophagus substrate was used for the detection and quantification of AKA antibodies in patients'sera. RESULTS: Overall 30/60 patients with JIA had sera positiveforAKA (50%, p=0.0005) ranging from 1:20 to 1:160 dilutions. Using the classification criteria for childhood idiopathic arthritis, AKA occurred in 2/7 patients with systemic disease (28.6%), in 13/30 patients with RF negative polyarthritis (43.3%, p=0.008) and in 12/18 RF positive polyarthritis (66.7%, p=0.002). AKA were also found in a small cohort of patients with oligoarthritis (1/3) and psoriatic arthritis (2/2). AKA positivity occurred in 3/26 healthy controls at a 1:20 dilution. The presence ofAKA was correlated as well as with the severity of the disease. Our study revealed that AKA was present overall in 16/29 patients (55.2%) with severe JIA and in 11/26 patients (42.3%) with non-severe disease. We also observed that AKA remained positive regardless of disease activity. AKA were detectable in 44.4% patients with active JIA and in 45.9% patients in the complete or near remission. CONCLUSION: Our data suggest that AKA are present in patients with JIA. However no correlation with severity or disease activity was observed.