Apoptosis enhanced by soluble factor produced in feline immunodeficiency virus infection

Feline immunodeficiency virus (FIV)-infected cells have been shown to undergo apoptosis by treatment with tumor necrosis factor alpha (TNF-alpha). This study detected a soluble factor which enhanced the apoptosis induced by TNF-alpha treatment. The sensitivity to TNF-alpha in the induction of apoptosis in a feline fibroblastoid cell line (CRFK) cells was significantly enhanced when the culture supernatant of FIV-infected CRFK cells or plasma samples from FIV-infected cats was added to the culture. These findings suggested that FIV infection induces production of a soluble factor which enhances CRFK cells sensitivity to TNF-alpha induction of apoptosis both in vitro and in vivo. This factor may contribute to the loss of lymphocytes in cats infected with FIV.