Enhancement Effect Of IFN-γ On The Phagocytosis,Killing Activity Of RAW264.7Macrophages Against Trichosporon Asahii

Objective1. To determine the effect of interferon-gamma(IFN–γ) on the phagocytosis and killingactivity of RAW264.7murine macrophage cell line against T.asahii.2.To investigate the effect of IFN-γ on the killing mechanism of RAW264.7macrophage against Trichosporon asahii（T.asahii）in vitro.Methods1. RAW264.7cells incubated with various concentrations of recombinant murineIFN–γ for18h, then incubated with T.asahii for45min or4h. The phagocytosis activityof RAW264.7cells against T.asahii were observed using an inverted microscope afterstained with Wright’s Giemsa stain45min later. The killing activity was assessed bycounting the number of colony forming units (CFU)4h later.2. The various concentrations（10U/ml、100U/ml、1000U/ml）of IFN–γ with RAW264.7were incubated, and then cultured with T.asahii to assess the killing activity bycounting the number of colony forming units per milliliter (CFU/ml)of T. asahii.Thencalculate the T.asahii growth inhibition rate, and measure Nitrite ion（NO2-）in thesupernatant. Each well added by the above different terminal concentrations of IFN–γincubated with RAW264.7to determine the superoxide anion (O2-) in the supernatant. Results1. IFN-γ enhanced the phagocytosis and killing activity of RAW264.7cells againstT.asahii in a concentration-dependent manner ranging from10-1000U/ml (P <0.01).2. With the concentrations (10U/ml、100U/ml and1000U/ml) of IFN–γ, the growthinhibition rates of T.asahii were25.21%、41.95%、55.83%respectively.There wassignificant difference between each group (P<0.01).In the supernatant theconcentrations of Nitrite ion were89.16±3.32、108.07±3.81、126.44±3.52respectively.There were significant difference (P<0.01) compared to the blank controlgroup（74.47±1.48）. With the concentrations of IFN–γ rising (10,100,1000U/mlrespectively), the OD value of the O2-measured in the supernatant were increasing(0.317±0.006、0.424±0.006、0.518±0.006respectively).And the blank control groupwas0.222±0.008, there was significant difference between each group（P<0.01）.Conclusions1. IFN-γ can enhance the effect of the phagocytosis and killing activity of RAW264.7cells against T.asahii.2.With the concentrations of IFN-γ rising，the growth inhibition rates of T.asahii areincreasing. IFN-γ plays a role in killing effect of T. asahii in vitro by enhancingmacrophage producing nitrogen monoxidum（NO）and O2-.