In vitro evaluation of the effect of a novel immunosuppressive agent, FTY720, on the function of feline neutrophils.
OBJECTIVE
To use in vitro assays to evaluate the effects of a novel immunosuppressive agent, FTY720, on biological functions (migration, phagocytosis, and production of reactive-oxygen species [ROS]) of feline peripheral neutrophils and determine the cytotoxic effects of FTY720 on feline peripheral neutrophils.


METHODS
Peripheral neutrophils obtained from 8 healthy cats.


METHODS
Peripheral neutrophils were isolated from blood samples obtained from the 8 cats and exposed to the phosphorylated form of FTY720 (FTY720-P). A fluorescence-based in vitro evaluation of migration was performed. Phagocytosis of microbes and production of ROS were evaluated by use of a 2-color flow cytometry system. Samples of whole blood obtained from the cats were incubated with various concentrations of FTY720-P, fluorescein-labeled Staphylococcus aureus, and dihydroethidium. Cytotoxic effects were evaluated by use of propidium iodide staining.


RESULTS
Addition of FTY720-P caused a slight non-significant decrease in phagocytosis and production of ROS by feline peripheral neutrophils. Migration activity of feline peripheral neutrophils was significantly increased by the addition of FTY720-P. Addition of FTY720-P at concentrations considered for clinical use did not increase the death rate of feline peripheral neutrophils.


CONCLUSIONS
FTY720 does not inhibit critical functions of feline peripheral neutrophils in vitro.
Comparative Transplantation Laboratory, Department of Surgical and Radiological Sciences and Center for Companion Animal Health, School of Veterinary Medicine, University of California, Davis, CA 95616-8745, USA.
Yi-Je
YJ
Chen
Andrew E
AE
Kyles
Clare R
CR
Gregory
D000818:Animals; D002415:Cats; D000068876:Fingolimod Hydrochloride; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007958:Leukocyte Count; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D010766:Phosphorylation; D011409:Propylene Glycols / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology
D007166:Immunosuppressive Agents; D011409:Propylene Glycols; D017382:Reactive Oxygen Species; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine