Epstein–Barr virus (EBV)-IgG and cytomegalovirus (CMV)-IgG titers in patients with ankylosing spondylitis (AS). AS patients were grouped according to the carrier status of circulating CD8+ CD28- T cells. Carrier status was defined as expressing >30% CD8+ CD28- T cells. IgG titers were determined by ELISA. No differences were seen.