IFNG and rheumatoid arthritis: We found no significant correlation between the number of EBV-specific IFNγ-producing T cells and disease activity (Disease Activity Score for 28 joints for RA patients (n = 64), P = 0.32; Bath Ankylosing Spondylitis Disease Activity Index for SpA patients (n = 21), P = 0.47) or disease duration (n = 88, P = 0.40).