Flow cytometric analysis and optimisation for measuring phagocytosis in three Australian freshwater fish

The phagocytic activity of fish immunocytes has been measured by a wide range of methods, and has been used as a bio-indicator to assess the immunotoxicity of environmental pollutants and the efficiency of immunostimulants used in aquaculture. This study demonstrates the utilisation of a flow cytometric technique for measuring phagocytosis as an alternative to manual evaluations by light microscopy. Optimal conditions for the phagocytosis of latex beads were ascertained, including incubation period, cell:bead ratio and media components, for head kidney cells isolated from three native Australian fish that inhabit the Murray-Darling basin, i.e. silver perch (Bidyanus bidyanus), golden perch (Macquaria ambigua) and crimson-spotted rainbowfish (Melanotaenia fluviatilis). Thus, standardised protocols have now been established for future use in the immunotoxicity testing of xenobiotics in native Australian freshwater fish.