Quantitative assessment of the expression of receptors for B cell–activating factor of the tumour necrosis factor family in muscle tissues. Cells positive for B cell–activating factor of the tumour necrosis factor family receptor (BAFF-R) (A), B cell maturation antigen (BCMA) (B) or transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) (C) per square millimetre of muscle tissue area are shown for healthy controls and patients with myositis with or without anti-Jo-1 and/or anti-Ro52/anti-Ro60 autoantibodies. IBM, Inclusion body myositis. Data presented are P- values calculated by Kruskal-Wallis (KW) test and Mann-Whitney (MW) U test. Horizontal bars represent medians for each group.