Abstract
Migration of neutrophils toward the supernatant of degranulated eosinophilic granular cells (EGCs) was examined using a modified Boyden chamber. EGCs of tilapia (Oreochromis niloticus) were isolated from the swim bladder membrane, and degranulated by incubation with substance P (neurotransmitter) or compound 48/80. The degranulation of the EGCs was also observed after incubation with normal tilapia sera containing zymosan, but not with heat-inactivated sera. Additionally, significantly higher neutrophil migration was observed when the degranulation of the EGCs occurred in the lower compartment of a Boyden chamber. High-speed centrifugation inhibited the degranulation of the EGCs stimulated by substance P or zymosan plus normal tilapia sera, and migration of neutrophils was inhibited. The results obtained in the present study suggest that neutrophil migration stimulating factor (s) are released by degranulation of EGCs in tilapia.
