[Natural cytotoxic function and ankylosing spondylitis].

Natural Killer (NK) cell function was evaluated in 28 ankylosing spondylitis (AS) patients (21 B27 positive), at one hand by the use of a Leu7 (HNK-1) monoclonal antibody, at the other hand by spontaneous cytotoxicity against a K562 cell line (preincubated with a fluorogenic substrate) evaluated by a flow cytometric assay. There is no difference in NK cell activity neither between AS patients and controls nor between B27 positive and negative AS. The study brings no evidence for a NK function control by the B27 gene. There is no correlation between NK activity and each of the other parameters investigated (ESR, B2m, IgA, Leu7, T4/T8). At the opposite, NK activity is significantly decreased (p = 0,006) in AS patients under NSAIDs treatment compared with non treated patients. NSAIDs rather enhance NK activity, the decrease observed in the present study could be due to evolution of the disease itself, and may be a pathogenetic factor contributing to remaining of bacterial antigens according to the current hypothesis of the disease's aetiology.