Specificity of Membrane Complement Receptor Type Three (CR3) for ß-Glucans

Publisher Website
Google Scholar
Abstract
The binding of the iC3b receptor (CR3) to unopsonized zymosan was shown to result from CR3 attachment to cell wall ß-glucans. A specificity of neutrophil responses for ß-glucan was first suggested by a comparison of yeast (Saccharomyces cerevisiae) cell wall components for stimulation of a neutrophil superoxide burst. Neutrophils responded poorly to heat-killed yeast, but gave increasingly better responses to cell wall polysaccharides devoid of proteins (zymosan) and nearly pure ß-glucan particles derived from zymosan. Zymosan triggered a burst that was 29% as great as that stimulated by phorbol myristate acetate (PMA), and ß-glucan particles stimulated a burst that was 72% as great as that produced by PMA. Phagocytic responses to yeast were also inhibited by soluble glucans but not by soluble mannans. Three types of experiments demonstrated a role for CR3 in these responses. First, neutrophil ingestion of either yeast or yeast-derived ß-glucan particles was blocked by monoclonal anti-CR3, fluid-phase iC3b, or soluble ß-glucan from barley. Monocyte ingestion of ß-glucan particles was also blocked by anti-CR3, but not by anti-CRi or anti-C3. Second, the neutrophil superoxide burst response to either zymosan or ß-glucan particles was blocked by anti-CR3 or fluid-phase iC3b, and was completely absent with neutrophils from 3 patients with an inherited deficiency of CR3. Third, CR3 was isolated from solubilized neutrophils by affinity chromatography on ß-glucan-Sepharose.

This publication has 0 references indexed in Scilit: