Fig. 1

Anti-Jo1 autoantibodies display high reactivity against HisRS full-length/variant/domains at IIM/ASSD diagnosis. A Schematic figure of HisRS versions used in the experiments. B The reactivity towards HisRS-FL, WHEP, CD, ABD, and SV as conformational epitopes was measured by ELISA in IgG purified from serum of 19 anti-Jo1⁺, 25 anti-Jo1⁻, and 24 healthy controls (HC). High reactivity (OD 450 nm) corresponds to strong blue color. C Anti-HisRS reactivity (ng/mL concentration) of anti-Jo1⁺ total IgG against HisRS-FL, WHEP, CD, ABD, and SV. Antibody titers were calculated using a standard curve (Supplementary Fig. 3B) and titers were measured in the linear range between 5 and 100 ng/mL. Median values for each antigen are indicated by the red line. D Anti-Jo1 reactivity against denatured HisRS antigens was addressed by WB in IgG purified from serum of 12 representative anti-Jo1⁺, 1 anti-Jo1⁻, and 1 HC. Strong band intensity denotes higher anti-Jo1 reactivity. Arrows indicate the molecular weight of the different HisRS variants (Supplementary Table 2, Supplementary Fig. 1). Some patients also showed an additional band, corresponding to the HisRS dimer. Friedman’s test corrected for multiple comparisons using Dunn’s test in (B, C) was applied. In B, the calculations were done only on Jo1+ patients. p < 0.05 was assumed as significantly different