Objective  The aim of our study was to detect the positive incidence and analyze the clinical significance of anti-PUF60 antibody in Chinese patients with idiopathic inflammatory myopathy(IIM).

  Methods  This study involved, from October 1989 to August 2016, 388 IIM patients (including 275 patients with dermatomyositis(DM), 76 patients with polymyositis(PM), and 37 patients with myositis overlap syndrome), 211 patients with control diseases (including 28 patients with noninflammatory neuromuscular disease(NMD), 104 patients with systemic lupus erythematosus(SLE), and 79 patients with Sj gren's syndrome(SS)) as disease controls, and 167 healthy adults as healthy controls(HCs). Enzyme-linked immunosorbent assay(ELISA) was developed to detect serum anti-PUF60 antibody, and immunoblotting analyses were performed to validate the ELISA results. The results of two groups were compared using unpaired Mann-Whitney U test, and the relevance was analyzed using Spearman correlation analysis.

  Results   Anti-PUF60 antibody was detected in 11.6%(45/388) of patients with IIM, 17.3%(18/104) of patients with SLE, and 10.1%(8/79) of patients with SS, and the antibody positive rates were significantly higher than that of HCs(P < 0.001, P < 0.001, and P=0.009, respectively). In IIM subgroups, anti-PUF60 antibody presented in 11.3%(31/275) of DM patients and 21.6%(8/37) of patients with myositis overlap syndrome, and the antibody positive rates were significantly higher than that of HCs(P=0.001 and P < 0.001, respectively). The clinical associations of anti-PUF60 antibody in different groups of immune disease were varied. Classical DM patients with anti-PUF60 antibody had lower prevalence of currently known myositis antibodies(P=0.018) and higher prevalence of mechanic's hands(P=0.046). While, the prevalence of anti-PUF60 antibody was particularly higher in the clinically amyopathic dermatomyositisc(CADM), subgroup and associated with the incidence of skin ulcer(P=0.029). As for other rheumatic diseases, in SS patients, anti-PUF60 antibody was significantly associated with higher prevalence of cutaneous manifestation, rheumatoid factor, and antibodies against SSB and RNP; in SLE patients, it is related to higher incidence of younger onset, alopecia, hypocomplementemia, elevated CD5⁺CD19⁺B-cell subpopulations, and antibodies against dsDNA, Sm and SSB.

  Conclusions   Anti-PUF60 antibody can be detected in Chinese patients with DM, myositis-overlap syndrome, SLE and SS; and it is associated with distinct clinical features in different rheumatic diseases. This finding indicates that anti-PUF60 antibody is associated with different pathogenesis processes in different systemic rheumatic diseases.