Neutrophils are critical for host defense against many viral, bacterial
and fungal pathogens (Densen and Mandell, 1990). Human
neutrophils exposed to either 4, 6 or 12M DE-71 have a greater
production of ROS than the cells exposed to either 0, 1 or 2M
DE-71. ROS are highly bactericidal (Ellis, 1999). Acidophilic granulocytes
which are neutrophil-like cells in teleosts display similar
functions to human neutrophils (Chaves-Pozo et al., 2005). Therefore,
the possibility exists that the acidophilic granulocytes of fish
fed the 10× PBDE diet produced a concentration of ROS that was
protective against L. anguillarum whereas those in fish fed the 1×
PBDE diet did not produce an ROS concentration that was protective
against the pathogen. An increased ROS response can come at a
price by overwhelming the fish’s antioxidant defense system which
can cause deleterious cellular effects such as lipid peroxidation and
protein oxidation