title: A beta-glucan inhibitable zymosan receptor on channel catfish neutrophils.
abstract: In mice and humans zymosan binds to the complement receptor three/Mac-1 receptor; however, identification of this receptor in channel catfish (Ictalurus punctatus) has not been accomplished. Soluble fluorescein isothiocyanate (FITC) conjugated beta-glucan, a component of zymosan, was found to bind to channel catfish anterior kidney (AK) neutrophils but not to B-lymphocytes. Serum activated zymosan (SAZ)-mediated chemiluminescence responses of channel catfish AK neutrophils could be inhibited by beta-glucan but not by mannan, and inhibition of chemiluminescence responses by beta-glucan was dose dependent. Similarly, phagocytosis of FITC-SAZ could be inhibited by beta-glucan in a dose-dependent manner. Treatment of channel catfish AK neutrophils with various concentrations of trypsin resulted in inhibition of phagocytosis of FITC-SAZ but not of Aeromonas hydrophila indicating that A. hydrophila phagocytosis was mediated by a trypsin-resistant receptor. Deleting serum or using heat-inactivated serum in the mixtures for the chemiluminescence and FITC-SAZ phagocytosis assays resulted in baseline readings. These data indicate that the beta-glucan component of zymosan is responsible for zymosan phagocytosis. Furthermore, the recognition of zymosan by a specific receptor is evident based on trypsin sensitivity assays. Based on these results it is proposed that a complement receptor 3, Mac-1-like receptor, is present on channel catfish AK neutrophils.
authors.affiliation: College of Veterinary Medicine, Mississippi State, MS 39762.
authors.forename: A J
authors.initials: AJ
authors.lastname: Ainsworth
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005936:Glucans / Q000494:pharmacology*; D007059:Ictaluridae / Q000378:metabolism*; D007668:Kidney / Q000166:cytology; D008163:Luminescent Measurements; D008351:Mannans / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D010587:Phagocytosis / Q000187:drug effects; D011951:Receptors, Complement / Q000187:drug effects / Q000378:metabolism*; D014357:Trypsin / Q000494:pharmacology; D015054:Zymosan / Q000378:metabolism
chemical_list: D005936:Glucans; D008351:Mannans; D011951:Receptors, Complement; C048084:zymosan receptor; D015054:Zymosan; D014357:Trypsin