In vitro effect of tumour necrosis factor antagonists on proliferative responses to recall antigens. The effect of infliximab (Ifx), adalimumab (Ada), and etanercept (Eta) (10 μg/ml) on the proliferation of lymphocytes was determined using the thymidine incorporation assay after 5 days of activation with purified protein derivative (PPD), Candida (Cd), cytomegalovirus (CMV), or Tetanus toxoid (TT). Five patients (3 from group III and 2 from group IV) were tested. Results (mean ± standard error of the mean) are expressed as percentage of controls, corresponding to cells cultured with a control antibody. *p < 0.05 and **p < 0.01 as compared with controls (Wilcoxon test with Bonferroni corrections).