The platelet functions in patients with ankylosing spondylitis: anti-TNF-alpha therapy decreases the mean platelet volume and platelet mass.

The present study was designed to investigate the interaction between platelet indices (mean platelet volume (MPV), platelet count (PLC) and platelet mass (PLM)), inflammatory markers and disease activity in ankylosing spondylitis (AS) subjects. The effects of anti-TNF-alpha therapy and conventional treatment on platelet indices were also compared. We studied 68 patients with AS (group I, 46 men, age: 36.4 +/- 6.9 years) and as control group 34 age and sex-matched healty subjects. All patients received conventional therapy (CT) at the beginning (Group I). The patients were reevaluated after 3 months according to Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score. Group II consisted of 35 subjects who responded to the CT and continued to take the same therapy for 3 months additionally. Group III consisted of 33 subjects who had a high disease activity score (BASDAI > 4) after 3 months and were accepted refractory to the CT therapy. In Group III the treatment was switched to infliximab and continued for 3 months at the standard intravenous dose. Significantly higher baseline MPV, PLC and PLM was reported as compared to controls decreased by therapy (9.12 +/- 1.20 vs. 8.35 +/- 0.94 fl, p < 0.001, 340 +/- 69 vs. 251 +/- 56 (x 10(3)/ microL) p < 0.0001, 3096 +/- 736 vs. 2110 +/- 384; p < 0.0001, respectively). In the same way, they were substantially lowered by both treatments in group II and group III. PLC and PLM were positively correlated with WBC and ESR (r : 0.44; p < 0.0001, r : 0.41; p = 0.001, r : 0.52; p < 0.0001, r : 0.41; p = 0.001), respectively) in AS patients. Additionally, MPV and PLM were positively correlated with BASDAI score (r : 0.41; p < 0.001, r = 0.29; p < 0.001 respectively). We have found that increased platelet activity reduced by therapy in AS patients. Additionally, it was correlated with inflammatory markers and disease activity. According to these results, it can be suggested that both anti-TNF-alpha and conventional therapy might contribute to a decrease in the risk of cardiovascular morbidity and mortality in AS patients.