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Published on: December 18, 2010
Effect of glucan on neutrophil dynamics and immune function in Escherichia coli peritonitis
D L Williams1, E R Sherwood, I W Browder
1Department of Physiology, Tulane University, School of Medicine, New Orleans, Louisiana 70112.
Abstract:
Previous studies from our laboratory have demonstrated that glucan, a nonspecific immunomodulator, modifies the course of murine Escherichia coli peritonitis. The protective effect of glucan was mediated, in part, by macrophages. In the present study, leukocyte dynamics in the peritoneal cavity and peripheral blood of glucan-treated mice following E. coli challenge was examined. Additional studies examined in vitro bone marrow proliferation, as well as phagocytosis and intracellular killing of E. coli by neutrophils following glucan administration. ICR/HSD mice were injected ip with glucan (150 mg/kg) or dextrose (5% w/v) on Days 5 and 3 prior to ip challenge with 1 X 10(8) E. coli. Glucan increased (P less than 0.05) total peritoneal neutrophil numbers prior to and following septic challenge. Examination of peripheral blood revealed that ip glucan treatment in E. coli peritonitis significantly (P less than 0.001) increased the number of circulating neutrophils. Additionally, neutrophils from glucan-treated mice showed increased phagocytosis of E. coli in vitro. Glucan therapy also increased bone marrow proliferation. We conclude that (1) glucan enhances peritoneal neutrophil levels, (2) peripheral blood neutrophils are increased following glucan and E. coli, (3) ip glucan increases bone marrow proliferation, and (4) neutrophils from glucan-treated mice showed enhanced phagocytosis of E. coli in vitro. Thus, the beneficial effect of glucan is mediated not only by activated macrophages, but also by the neutrophilic leukocyte.
Insights
Glucan immunotherapy boosts neutrophil activity, enhancing the body's defense against Escherichia coli peritonitis. This immunomodulator improves neutrophil numbers and function, complementing macrophage-mediated protection.
Area of Science:
- Immunology
- Microbiology
Background:
- Glucan, a nonspecific immunomodulator, previously showed protective effects against murine Escherichia coli peritonitis, partly mediated by macrophages.
- The precise mechanisms underlying glucan's protective effects require further elucidation, particularly concerning leukocyte involvement.
Purpose of the Study:
- To investigate the impact of glucan administration on leukocyte dynamics in mice challenged with Escherichia coli.
- To examine the effects of glucan on neutrophil phagocytosis, intracellular killing of E. coli, and bone marrow proliferation in vitro and in vivo.
Main Methods:
- ICR/HSD mice were administered glucan (150 mg/kg) or dextrose intraperitoneally (ip) on specific days before an ip challenge with E. coli.
- Leukocyte counts in peritoneal fluid and peripheral blood were analyzed.
- In vitro assays assessed neutrophil phagocytosis and intracellular killing of E. coli.
- Bone marrow proliferation was also examined.
Main Results:
- Glucan significantly increased peritoneal neutrophil numbers before and after E. coli challenge.
- Intraperitoneal glucan treatment led to a significant increase in circulating neutrophils in peripheral blood.
- Neutrophils from glucan-treated mice exhibited enhanced in vitro phagocytosis of E. coli.
- Glucan administration also stimulated bone marrow proliferation.
Conclusions:
- Glucan enhances peritoneal neutrophil levels and bone marrow proliferation.
- Glucan treatment increases peripheral blood neutrophils following E. coli infection.
- Neutrophils from glucan-treated mice demonstrate improved in vitro phagocytosis of E. coli.
- The protective effects of glucan in E. coli peritonitis are mediated by both macrophages and neutrophils.
