Suppressed neutrophil oxidative activity in sepsis: a receptor-mediated regulatory response

We have reported that neutrophils from patients with intraabdominal sepsis show suppressed superoxide production in response to soluble chemoattractants. To determine whether this could be a result of altered receptor function, neutrophil function studies and characterization of receptors were performed upon 22 patients recently operated upon for intraabdominal sepsis. Patient cells showed an absence of subagarose migratory response to activation serum (C5) but intact FMLP response. Superoxide production to FMLP was 5.3 +/- 0.1 nmole FcC compared to 11.2 +/- 0.1 nmole for laboratory normals. Addition of cytochalasin B reversed this. Scatchard analyses of patients' cells showed affinity of 55.5 +/- 0.6 as compared to 36.5 +/- 1.8 for controls. The number of receptors of cell was approximately 55,000 for both controls and patients. Internalization studies revealed significant increase in tritiated-FMLP uptake at room temperature. These results support the hypothesis that superoxide suppression is due to enhanced clearance of stimulant by enhanced internalization of the receptor-ligand complex.