Research Abstract

Surgery 2004;136:384-9.

ß-glucan Affects Leukocyte Navigation in a Complex Chemotactic Gradient

Vassiliki L. Tsikitis, MD, Jorge E. Albina, MD, and Jonathan S. Reichner, PhD, Providence, RI

Abstract

Background. Polymorphonuclear leukocytes (PMNs) must traverse endogenous chemotactic gradients (interleukin 8 [IL-8]) before reaching target chemoattractants (fMLP [N-formylmethionine-leucinephenylalanine], C5a) produced at a site of bacterial infection. Complement receptor 3 (CR3; CD11b/ CD18) contains 2 distinct binding sites, one that mediates adhesion and a lectin-like domain (LLD) that binds polysaccharides of microbial origin. This laboratory previously reported an increase in the chemotactic capacity of PMNs toward fMLP upon ligation of the CR3 LLD with ß-glucan, a CR3 agonist. Current studies sought to determine the effect of ß-glucan on PMN navigation toward other
chemoattractants alone and in a competing chemotactic environment.

Methods. Migration was assessed by serum agarose overlay with the use of chambered slides containing or not, ß-glucan. Migration of human PMNs at 378C for 2 hours was evaluated toward C5a or IL-8 alone and in competing gradients. Selected groups were treated with anti-CR3eblocking antibodies. The number of chemotactic cells was quantified by microscopy.

Results. ß-glucan significantly enhanced chemotaxis toward C5a and suppressed that toward IL-8 in a CR3-dependent fashion. In the competing chemotactic gradient assays (C5a vs IL-8), b-glucan further enhanced migration toward C5a while not affecting that toward IL-8.

Conclusions. ß-glucan selectively upregulates PMN chemotaxis toward C5a while suppressing chemotaxis toward IL-8.