Clinical associations of anti-Jo1 antibodies in a Moroccan population

Anti-Jo1 antibodies are usually known markers of myositis. However, they can be associated with different pathologies. We aimed to determine the immuno-clinical characteristics of patients with positive anti-Jo1. We enrolled 31 anti-Jo1 positive patients, selected from 10429 cases tested for antinuclear antibodies (ANA) by indirect immunofluorescence. The anti-Jo1 identification was motivated by the ANA pattern or the clinical data of patients. The average age of patients was 36.9 ± 10 years (F/M sex ratio: 3.4). The overall prevalence of anti-Jo1 was 0.3% among all ANA-tested cases. The ANA pattern associated with the presence of anti-Jo1 was heterogeneous with ANA negative in 38.7 % of cases. They were associated with different autoantibody specificities in 64.5 % of cases and were alone in 35.5% of cases. When confronted with clinical data, anti-Jo1 positivity was associated with autoimmune (77,4%) and non-autoimmune (22,6%) clinical conditions. Our study shows a low overall prevalence of anti-Jo1. These antibodies must be systematically tested for in the context of myositis even if ANA is negative. Nevertheless, their positivity in other systemic or even non-autoimmune diseases requires further studies to better understand their clinical significance.