Cytokines and inhibitors in plasma were measured in 44 patients with typhoid fever. Ex vivo production of the cytokines was analyzed in a whole blood culture system with and without lipopolysaccharide (LPS). Acute phase circulating concentrations of cytokines (+/- SD) were as follows: interleukin (IL)-1 beta, < 140 pg/mL; tumor necrosis factor-alpha (TNF alpha), 130 +/- 50 pg/mL; IL-6, 96 +/- 131 pg/mL; and IL-8, 278 +/- 293 pg/mL. Circulating inhibitors were elevated in the acute phase: IL-1 receptor antagonist (IL-1RA) was 2304 +/- 1427 pg/mL and soluble TNF receptors 55 and 75 were 4973 +/- 2644 pg/mL and 22,865 +/- 15,143 pg/mL, respectively. LPS-stimulated production of cytokines was lower during the acute phase than during convalescence (mean values: IL-1 beta, 2547 vs. 6576 pg/mL; TNF alpha, 2609 vs. 6338 pg/mL; IL-6, 2416 vs. 7713 pg/mL). LPS-stimulated production of IL-1RA was higher in the acute than during the convalescent phase (5608 vs. 3977 pg/mL). Inhibited production of cytokines during the acute phase may be due to a switch from a proinflammatory to an antiinflammatory mode.