Abstract
Circulating CD8(+) CD28(-) T cells were found to be expanded more in patients with ankylosing spondylitis than in an age-matched healthy population (41.2 +/- 17.7% versus 18.6 +/- 7.6%). The level of CD8(+)CD28(-) T cells was dependent on the disease status, but was independent of age. Most of the CD8(+) CD28(-) T cells produced perforin after stimulation in vitro, in contrast to their CD8(+)CD28(+) counterparts. From the clinical perspective, the percentage of the cytotoxic CD8(+) CD28(-) T cells reflected a more severe course of disease, as it correlated with distinct movement restrictions, as well as the metrology score summarizing cervical rotation (in sitting position), chin-to-jugulum distance, thoracic Schober, chest expansion, and fingers-to-floor distance (P = 0.032).