Cytokine correlates of clinical response patterns to infliximab treatment of ankylosing spondylitis.

OBJECTIVE: To identify clinical and immunological markers of response to treatment with infliximab in ankylosing spondylitis (AS).

METHODS: Baseline and sequential cytokine levels (IL1, TNFalpha, IFNgamma, TGFbeta and IL10) were examined after 52 weeks of infliximab treatment 5 mg/kg in 22 patients.

RESULTS: At week 52, 18 patients were responders and four non-responders according to ASAS group criteria. Clinical measures of disease activity between the two groups at baseline were similar, apart from a trend towards longer disease duration in non-responders (p = 0.08). Baseline CRP and TNFalpha levels were higher in responders than non-responders (p<0.01 and p<0.006, respectively). The two groups had similar baseline cytokine levels, apart from TNFalpha. Baseline CRP levels did not correlate significantly with baseline cytokine levels in responders, but a strong correlation was noted between baseline CRP and IL1, IFNgamma, and IL10 in non-responders. Apart from an early rise in TGFbeta and a decrease in IL10 in responders after the first infusion, sequential cytokine analysis for the first six months of treatment was not related to clinical disease activity measures.

CONCLUSION: Although sequential cytokine analysis does not appear to be informative, baseline CRP and TNFalpha levels are useful markers of clinical response patterns in patients with AS treated with infliximab.