Mass cytometry reveals an impairment of B cell homeostasis in anti-synthetase syndrome.

Recent data suggest the implication of T, B and NK cells in the anti-synthetase syndrome (ASyS); nevertheless their role and activation states are poorly described. We performed deep immune-profiling using 37 markers on peripheral blood cells from 10 ASyS patients versus 17 healthy donors (HD) and 26 myositis control patients. We show decreased percentages of memory B cells in ASyS patients (mean ± SEM: ASyS = 13 ± 3%, HD = 37 ± 4% and 'myositis controls' = 32 ± 3), counterbalanced by increased percentages of naïve B cells. Interestingly, perifascicular infiltrations of memory B cells within muscle biopsies of ASyS patients suggest that they niche within the muscle.