Defective natural killer cell cytotoxic activity in feline immunodeficiency virus-infected cats

Flow cytometry has been employed to study NK cell cytotoxic activity in cats infected with feline immunodeficiency virus. The results show that animals infected for 12 months or more have decreased levels of NK cell cytotoxic activity in their blood. The impairment could not be overcome by in vitro treatment of effector cells with interleukin 2. Additional results suggest that the NK cells of infected cats are defective, in that they are still able to bind to target cells but have a reduced ability to kill them.