IFNG and rheumatoid arthritis: The positive rate of anti-IFN-γ IgG in SLE patients with severe infections, SLE patients without severe infections, AS, RA, and HC were 16/55 (29.1%), 11/120 (9.2%), 1/24 (4.2%), 1/24 (4.2%), and 0%, respectively, indicating that anti-IFN-γ IgG might be involved in the pathogenesis of SLE with severe infections.