ObjectiveTo determine the effects of intra-abdominal sepsis on polymorphonuclear leukocyte tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) receptor expression.DesignProspective, randomized comparison between patients undergoing elective colon surgery vs. patients with intra-abdominal sepsis.SettingTertiary-care center with all patients with intra-abdominal sepsis in a surgical ICU environment.PatientsGroup 1 (n = 7) represents control patients who underwent elective colon surgery without intra-abdominal sepsis. Group 2 (n = 10) represents patients with intra-abdominal sepsis.Measurements and Main ResultsPolymorphonuclear leukocyte TNF-α and IL-1β receptor expression ± stimulation of the oxidative burst was measured using125I TNF-α and125I IL-1β. Superoxide anion production and candicidal activity were measured in the presence of TNF-α and IL-1β. Group 2 patients expressed fewer TNF-α and IL-1β receptors on their cell surface, and stimulation of oxidative burst reduced TNF-α and IL-1β receptor expression in group 2 more than in group 1. Diminished TNF-α and IL-1β binding reduced superoxide anion production by group 2 polymorphonuclear leukocytes. Decreased TNF-α binding but not IL-1β, reduced polymorphonuclear leukocyte candicidal activity by group 2 polymorphonuclear leukocytes.Conclusionsa) Intra-abdominal sepsis reduces polymorphonuclear leukocyte TNF-α and IL-1β receptor expression. b)Expression of these surface receptors is altered by stimulation of the polymorphonuclear leukocyte oxidative burst. c) Diminished TNF-α and IL-1β receptor expression is associated with functional impairments in polymorphonuclear leukocyte activity. (Crit Care Med 1992; 20:11)