title: Comparison of the chemiluminescence responses of bovine neutrophils to differently opsonized zymosan particles.
abstract: Stimulatory effects of 6 zymosan preparations on luminol-dependent chemiluminescence (CL) responses of isolated bovine neutrophils were compared. Unopsonized zymosan particles and zymosan particles opsonized with bovine IgG1, IgG2, fresh serum, or serum from which zymosan-specific antibodies, but not complement, had been removed (C3-serum) induced strong CL responses, with nearly equal maximal peaks in the presence of extracellular Ca2+ and Mg2+, whereas the response to fetal bovine serum-opsonized zymosan particles was markedly low. Removal of extracellular divalent cations almost completely blocked the CL reaction triggered by unopsonized, IgG1-opsonized, C3-opsonized, and fetal bovine serum-opsonized zymosan particles. By contrast, no change in the respiratory burst activity induced by serum-opsonized zymosan and only partial reduction in the response to IgG2-opsonized zymosan were seen under these conditions. Further experiments were performed with 4 zymosan preparations on neutrophils isolated from 2 calves with a genetic deficiency of CD11/CD18 membrane antigens. The unopsonized zymosan-induced CL reaction was absent in these cells. A reduced, but clear, response was observed with C3-opsonized zymosan. Unexpectedly, in the absence of extracellular Ca2+ and Mg2+, serum-opsonized zymosan failed to generate the respiratory burst, whereas response to IgG2-opsonized zymosan was normal in the CD11/CD18-deficient neutrophils. These findings indicate that unopsonized zymosan may act in a divalent cation-dependent manner at the receptor for C3bi in bovine neutrophils, as it has been shown to do in the human system. In addition, it seems that IgG2-Fc receptors capable of signaling the respiratory burst in the absence of extracellular Ca2+ and Mg2+ exist on bovine neutrophils.
authors.affiliation: Department of Hematology, Turku University Central Hospital, Finland.
authors.forename: L
authors.initials: L
authors.lastname: Leino
authors.forename: M J
authors.initials: MJ
authors.lastname: Paape
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000502:physiology; D018845:CD11 Antigens; D018821:CD18 Antigens; D002417:Cattle; D005260:Female; D007074:Immunoglobulin G / Q000145:classification / Q000378:metabolism; D007700:Kinetics; D007774:Lactation / Q000097:blood; D008163:Luminescent Measurements; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D016028:Receptors, Leukocyte-Adhesion / Q000502:physiology; D012441:Saccharomyces cerevisiae; D013997:Time Factors; D015054:Zymosan / Q000494:pharmacology*
chemical_list: D015703:Antigens, CD; D018845:CD11 Antigens; D018821:CD18 Antigens; D007074:Immunoglobulin G; D016028:Receptors, Leukocyte-Adhesion; D015054:Zymosan