Effects of TNF-α on expression of pattern recognition receptors in vitro and in vivo. (a) Peripheral blood mononuclear cells were stimulated with 20 ng/ml tumour necrosis factor-α (TNF-α) for 24 hours, and CD4+CD28null T cells were analysed for expression of CD14, TLR4 and TLR2. Box plots summarize data from seven independent experiments. Medians were compared using the Wilcoxon test. ***P < 0.001, **P < 0.01. (b) CD4+CD28null T cells in patients with active ankylosing spondylitis treated with infliximab at a dosage of 3 mg/kg body weight were tested for the expression of pattern recognition receptors (PRRs) before and 3 weeks after injection (n = 8). The expression of CD14, TLR4 and TLR2 was detected by flow cytometry. The Wilcoxon test was used to determine differences in expression of PRRs before (pre) and under successful TNF-α blocking treatment (post). **P < 0.01, *P < 0.05.