Tumour necrosis factor-α (tnf-α) levels and influence of -308 TNF-α promoter polymorphism on the responsiveness to infliximab in patients with rheumatoid arthritis

Objective: To investigate the influence of −308 tumour necrosis factor‐α (TNF‐α) promoter polymorphism and circulating TNF‐α levels in the clinical response to the infliximab treatment in patients with rheumatoid arthritis (RA).Methods: One hundred and thirty‐two RA patients were genotyped for TNF‐α promoter by polymerase‐chain reaction restriction fragment‐length polymorphism (PCR‐RFLP) analysis. Ten patients with the −308 TNF‐α gene promoter genotype G/A, and 10 with the G/G genotype were selected and received 3 mg/kg of infliximab at Weeks 0, 2, 6, and 14.Results: Both groups showed a significant improvement with treatment in all variables studied. Total mean TNF‐α levels increased significantly with respect to basal levels in most of patients after treatment [probability (p)=0.04]. Only patients from G/A showed a statistically significant correlation between ACR 50 and the increase of TNF‐α levels (p<0.03).Conclusion: A relationship was detected between ACR criteria of improvement and increased circul...