ENHANCED EXPRESSION OF NOVEL CD57(+)CD8(+) LAK CELLS FROM CATS INFECTED WITH FELINE IMMUNODEFICIENCY VIRUS

As a model for lymphokine-activated killer (LAK) function in HIV infec tion, we studied LAK cells in cats infected with feline immunodeficien cy virus (FIV), which causes an acquired immunodeficiency syndrome. Pe ripheral blood mononuclear cells cultured in concanavalin A and interl eukin-2 developed LAK cytotoxicity against chronically FIV-infected Cr FK cells and acutely infected CD4+ lymphocytes but not uninfected cell s. LAK cells from FIV+ cats were more cytotoxic than LAK cells from un infected cats. Enhanced FIV+ LAK cytotoxicity against feline leukemia virus-infected cells (FL74) suggested that the cytotoxicity was not an tigen specific. Two-color fluorescence-activated cell sorter analysis and antibody depletion studies demonstrated that the majority of LAK c ells and their progenitors were positive for both CD8 and CD57. The in vitro induction of dual positive CD8(+)CD57(+) LAK cells was enhanced in FIV+ cats, as reported for HIV+ patients. These CD8(+)CD57(+) LAK cells may play a role in maintaining the long asymptomatic stage of in fection in FIV+ cats.