The effects of five different glycans on innate immune responses by phagocytes of hybrid tilapia and Japanese eels Anguilla japonica.
The aim of this study was to evaluate the immune responses in hybrid tilapia (Nile tilapia Oreochromis niloticus x Mozambique tilapia O. mossambicus) and Japanese eels Anguilla japonica after treatment with five glycans: barley, krestin, MacroGard, scleroglucan, and zymosan. The effects of the glycans on the innate immune responses of the fish were investigated using the phagocytic index (PI), lysozyme activity, complement opsonization, and activation assay. The results of the lysozyme assay demonstrated that the lysozyme activities increased after treatment with glycans. Moreover, based on the PI, treatment with each of the five glycans resulted in increased phagocytic activities in anterior kidney and peripheral blood phagocytes in both tilapia and Japanese eels. The opsonic effect of complement on phagocytosis in tilapia and Japanese eels were investigated using baker's yeast, which served as the activator in the classical complement pathway (CCP) and in the alternative complement pathway (ACP). Tilapia and Japanese eel sera that were treated with glycans greatly enhanced phagocytosis. The classical pathway--hemolytic complement titer (CH50) of Japanese eels treated with glycans was slightly increased in vitro and in vivo. While glycan treatment enhanced the CCP of both species in vitro and in vivo, the alternative pathway-hemolytic complement titer (ACH50) was only increased in vitro and in vivo in glycan-treated tilapia. Thus, it follows that the ACP must have been activated in tilapia treated with glycans. However, in Japanese eels, the ACH50 of the ACP activation assay was undetected in vitro or in vivo due to possible unknown factors in the Japanese eel serum that caused lysis of the rabbit red blood cells. Our study investigated the effects of glycans used to enhance phagocytosis and activate both of the complement pathways involved in stimulating the innate immune responses of Japanese eels and tilapia.
Wang
Way-Shyan
WS
Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, Taichung 402, Taiwan. wswang@dragon.nchu.edu.tw
Hung
Shao-Wen
SW
Lin
Yu-Hsing
YH
Tu
Ching-Yu
CY
Wong
Min-Liang
ML
Chiou
Shiow-Her
SH
Shieh
Meng-Tong
MT
D000818:Animals; D003167:Complement Activation / Q000187:drug effects*; D003170:Complement Pathway, Alternative / Q000187:drug effects*; D004306:Dose-Response Relationship, Immunologic; D004524:Eels / Q000276:immunology*; D005936:Glucans / Q000494:pharmacology; D001467:Hordeum; D007113:Immunity, Innate; D009113:Muramidase / Q000378:metabolism; D010587:Phagocytosis / Q000187:drug effects*; D011134:Polysaccharides / Q000494:pharmacology*; D011509:Proteoglycans / Q000494:pharmacology; D017210:Tilapia / Q000276:immunology*; D015054:Zymosan / Q000494:pharmacology; D047071:beta-Glucans
D005936:Glucans; D011134:Polysaccharides; D011509:Proteoglycans; D047071:beta-Glucans; C045938:scleroglucan; C010770:polysaccharide-K; D015054:Zymosan; C033363:beta-1,3-glucan; D009113:Muramidase