HSPG2 and rheumatoid arthritis: As a group, sera from patients with SLE (p < 0.001 versus RA, p < 0.05 versus SSc, p < 0.01 versus PM/DM, p < 0.001 versus normal human serum (NHS)) and SjS (p < 0.001 versus RA or NHS, p < 0.05 versus SSc, p < 0.01 versus PM/DM) showed high reactivity.