Proliferative responses to recall antigens in patients with immune-mediated inflammatory disease. The proliferative response to purified protein derivative (PPD), Candida (Cd), cytomegalovirus (CMV), Tetanus toxoid (TT), and Toxoplasma gondii (Toxo) was evaluated using the thymidine incorporation assay. Patients were from group I (dotted boxes) (n = 28) and from group II (gray shaded boxes) (n = 26), before TNF (tumour necrosis factor) antagonist administration, and from group III (diagonally lined boxes) (n = 20) and from group IV (horizontally lined boxes) (n = 14). Results are expressed as stimulation indices (SIs) (mean ± standard error of the mean). P > 0.05 for all comparisons between groups I and III and between groups II and IV, Mann-Whitney U test.