Location of superoxide production sites in turbot neutrophils and gilthead seabream acidophilic granulocytes during phagocytosis of glucan particles

Here we show, by spectrophotometry and enzyme cytochemical methods, that turbot neutrophils and gilthead seabream acidophils responded in a similar way when incubated with PMA or with Particulate glucans. Cells stimulated with PMA released high amounts of superoxide both intra- and extracellularly. However, O-2(-) was mainly released intracellularly when cells were incubated with particulate glucans. Small glucan particles were quickly phagocytosed and O-2(-) was initially produced in intracellular vesicles and tubular structures that later fused with the phagosome or with the cell membrane. Large glucan filaments that were not phagocytosed also induced cell stimulation and O-2(-) was also produced in intracellular vesicles which then appeared to fuse with the cell membrane. We conclude that, in stimulated turbot neutrophils and gilthead seabream acidophils, superoxide production is carried out initially in intracellular compartments that are very similar to those described in mammalian neutrophils. (C) 2001 Elsevier Science Ltd. All rights reserved.