Abstract
Sixteen patients with Bechterew's syndrome (ankylosing spondylitis, AS) were investigated. All except one of the patients were HLA B27-positive. Peripheral blood lymphocytes from the patients were examined for spontaneous cytotoxicity against 51Cr-labelled K562 target cells. The cytotoxicity index of the non-T lymphocytes was negatively correlated with the serum CRP concentration (Pearson's r=0.613, p<0.02). This finding seems to be caused by an alteration of the natural killer (NK) cell activity of the non-T lymphocytes during the active phase of the disease and not due to serum factors. The activity of the non-T cell fraction was slightly but not significantly reduced in patients with high disease activity (CRP>0.01 g/l) compared with normal controls, (14.6±2.8 g/l versus 20.4±2.4 g/l mean ±SE; p<0. 10) Serum IgG and IgA concentrations were increased (p<0.001 and p<0.05 respectively) Interferon caused normal augmentation in the NK cell activity in AS patients, and no correlation was found between serum gamma interferon titres and the NK cell activity.