Zymosan-induced luminol-dependent chemiluminescence response of circulating and extravasated leukocytes in experimental sepsis

This study examines a concurrent profiling of circulating and extravasated polymorphonuclear leukocytes (PMNs) in a rat model of experimental sepsis. Fecal peritonitis was induced in Wistar male rats by intraperitoneal instillation of a fecal suspension in saline ( 1: 1 w/v). Blood and peritoneal fluid were collected 8 h following fecal inoculation for the evaluation of inflammatory response of PMNs using zymosan-induced luminol-dependent chemiluminescence. Fifty microliters of pre-diluted blood or peritoneal fluid samples were mixed with 150 mul of reaction mixture ( 4 x 10(-4) M luminol + 50 mug opsonized zymosan + 0.1% gelatin in Hank's balanced salt solution) and the chemiluminescence signal was measured in a luminometer at 37degreesC. Fecal peritonitis caused a significant leukocytopenia (3540 +/- 297 mm(-3) versus control value of 7525 +/- 711 mm(-3), p< 0.001) accompanied by massive infiltration of PMNs in the peritoneal cavity (34700 +/- 4006 versus 7325 +/- 425 mm(-3), p< 0.001). The phagocytic activity of circulating blood PMNs was down-regulated whereas a significant up-regulation was observed in the activity of PMNs from peritoneal fluid. In conclusion, this study clearly demonstrates sepsis-induced alterations in both blood and peritoneal fluid PMNs and their quantitative assessment may be helpful in disease evaluation and designing effective therapies.