title: Binding of Soluble Yeast β-Glucan to Human Neutrophils and Monocytes is Complement-Dependent.
abstract: The immunomodulatory properties of yeast β-1,3/1,6 glucans are mediated through their ability to be recognized by human innate immune cells. While several studies have investigated binding of opsonized and unopsonized particulate β-glucans to human immune cells mainly via complement receptor 3 (CR3) or Dectin-1, few have focused on understanding the binding characteristics of soluble β-glucans. Using a well-characterized, pharmaceutical-grade, soluble yeast β-glucan, this study evaluated and characterized the binding of soluble β-glucan to human neutrophils and monocytes. The results demonstrated that soluble β-glucan bound to both human neutrophils and monocytes in a concentration-dependent and receptor-specific manner. Antibodies blocking the CD11b and CD18 chains of CR3 significantly inhibited binding to both cell types, establishing CR3 as the key receptor recognizing the soluble β-glucan in these cells. Binding of soluble β-glucan to human neutrophils and monocytes required serum and was also dependent on incubation time and temperature, strongly suggesting that binding was complement-mediated. Indeed, binding was reduced in heat-inactivated serum, or in serum treated with methylamine or in serum reacted with the C3-specific inhibitor compstatin. Opsonization of soluble β-glucan was demonstrated by detection of iC3b, the complement opsonin on β-glucan-bound cells, as well as by the direct binding of iC3b to β-glucan in the absence of cells. Binding of β-glucan to cells was partially inhibited by blockade of the alternative pathway of complement, suggesting that the C3 activation amplification step mediated by this pathway also contributed to binding.
authors: Biothera , Eagan, MN , USA.
authors: Nandita
authors: N
authors: Bose
authors: Anissa S H
authors: AS
authors: Chan
authors: Faimola
authors: F
authors: Guerrero
authors: Carolyn M
authors: CM
authors: Maristany
authors: Xiaohong
authors: X
authors: Qiu
authors: Richard M
authors: RM
authors: Walsh
authors: Kathleen E
authors: KE
authors: Ertelt
authors: Adria Bykowski
authors: AB
authors: Jonas
authors: Keith B
authors: KB
authors: Gorden
authors: Christine M
authors: CM
authors: Dudney
authors: Lindsay R
authors: LR
authors: Wurst
authors: Michael E
authors: ME
authors: Danielson
authors: Natalie
authors: N
authors: Elmasry
authors: Andrew S
authors: AS
authors: Magee
authors: Myra L
authors: ML
authors: Patchen
authors: John P
authors: JP
authors: Vasilakos
keywords: C3; CR3; monocytes; neutrophils; opsonization; β-glucans
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