RELEASE OF NATURAL-KILLER CYTOTOXIC FACTOR (NKCF) FROM CANINE NATURAL-KILLER (NK) CELLS STIMULATED WITH CYTOPLASMIC MEMBRANE OF TARGET-CELLS

The presence of canine natural killer cytotoxic factor (NKCF) and the mechanism of the release of the NKCF by canine natural killer (NK) cells were studied. The cytotoxicity in the culture supernatant of effector cells cultured with target cells was dependent on the count of NK cells. Therefore, this suggests that the cytotoxic factor in this culture supernatant is NKCF. The NK-sensitive live target cells stimulated the release of NKCF from NK cells, but the NK-insensitive target cells did not. Moreover, NKCF was also released from NK cells stimulated with either killed target cells or their cytoplasmic membrane as well as live target cells. These findings suggest that the structure of the cytoplasmic membrane of target cells is involved in the recognition, binding and the release of NKCF by NK cells.