Membrane complement receptor type three (CR3) has lectin-like properties analogous to bovine conglutinin as functions as a receptor for zymosan and rabbit erythrocytes as well as a receptor for iC3b.

作者：G D Ross, Judith A. Cain, Phillip J. Lachmann · 发表于：The Journal of Immunology · 年份：1985 · DOI：10.4049/jimmunol.134.5.3307 · 被引用次数：421 · 研究领域：Complement system in diseases、Glycosylation and Glycoproteins Research、Monoclonal and Polyclonal Antibodies Research

Human leukocyte complement receptor type three (CR3) was shown to be lectin-like and to resemble bovine serum conglutinin (K) in that it bound to both iC3b and unopsonized yeast (Saccharomyces cerevisiae), and was inhibited by EDTA or N-acetyl-D-glucosamine (NADG). CR3 and K also bound to zymosan (Z), a yeast cell wall extract that contains primarily polysaccharide and no detectable protein. However, structural differences and the absence of K on bovine phagocytes indicated that CR3 was not the human homologue of bovine K. Phagocytic and respiratory responses to unopsonized Z were CR3 dependent because they were inhibited by monoclonal antibodies specific for the alpha-chain of CR3 and did not occur with phagocytes from patients with a genetic deficiency of CR3. The binding of CR3 to Z did not require opsonization of the Z with neutrophil-secreted C3, as Z binding and responses were not inhibited by Fab anti-C3. In addition, CR3-dependent binding of yeast occurred with neutrophils from which protein secretion was blocked by fixation with paraformaldehyde. Rabbit erythrocytes (RaE) also bound weakly to neutrophil CR3 and triggered ingestion. Anti-CR3 not only blocked the binding and ingestion of RaE but also blocked selectively the ingestion of RaEC3b without affecting the strong binding mediated by CR1. Even though sheep E and sheep EC3b were not ingested by neutrophils, a weak binding of CR3 to sheep E was suggested by the finding of 20 to 40% inhibition of sheep EAIgG inges...