The Importance of Hydrogen Peroxide in Phagocytic Bactericidal Activity of Japanese Eel Neutrophils.

Abstract

The bactericidal activity of Japanese eel neutrophils in the presence of oxygen radical scavengers was investigated.Catalase inhibited bacterial killing, while superoxide dismutase and hydroxyl radical scavengers (D-mannitol, sodium benzoate) did not. Superoxide dismutase had no synergetic effect with catalase. These observations indicate that hydrogen peroxide acts as a potent factor in the bactericidal process by eel neutrophils.The phagocytic index of cytochalasin B-treated neutrophils was less than one third of that of control neutrophils, although their phagocytic rate was more than 90%. Cytochalasin B, which inhibits phagosome formation without suppressing radical production, decreased the bactericidal activity of the neutrophils, and catalase did not affect the bacterial killing of cytochalasin B-treated neutrophils.Exposure to hydrogen peroxide at concentrations, which are expected within eel neutrophils during the respiratory burst, effectively killed the bacteria tested. Thus, it is suggested that the hydrogen peroxide-dependent bactericidal activity in eel neutrophils is expressed only within phagosomes but not extracellularly and that phagosome formation is essential for this activity.

Pre- and post-challenge immuno-haematological changes in Labeo rohita juveniles fed gelatinised or non-gelatinised carbohydrate with n-3 PUFA

“…This process is known as respiratory burst. These reactive oxygen intermediates have been reported to have potent bactericidal activities against fish bacterial pathogens [30,31]. Increased respiratory burst activity in the NG carbohydrate fed groups before challenge in this study is supported by the observation of Kumar et al [9] in L. rohita.…”

Immunomodulation of Labeo rohita juveniles due to dietary gelatinized and non-gelatinized starch

“…These reactive oxygen intermediates have been reported to have potent bactericidal activities against fish bacterial pathogen [29,30]. In the present study the respiratory burst activity of phagocytes was measured by reduction of nitroblue tetrazolium (NBT) by intracellular superoxide radicals produced by leukocytes.…”

KocuriaSM1 controls vibriosis in rainbow trout (Oncorhynchus mykiss, Walbaum)

“…These can be associated with the extracellular killing of pathogens (Hardie et al. 1996; Secombes 1996; Itou et al. 1997).…”