Effects of recombinant canine interferon-γ injected before general anesthesia with propofol and isoflurane on natural killer cytotoxic activity during anesthesia in dogs

Abstract

We aimed to determine whether subcutaneous injection of recombinant canine interferon-γ (rCaIFN-γ) 1h before general anesthesia with a combination of propofol and isoflurane (P-I) changes the cytotoxic activity of natural killer (NK) cells during anesthesia in dogs. Nine clinically healthy beagles were assigned to one of two groups: rCaIFN-γ–treated group (n=5) and control group (no treatment, n=4). One hour before P-I anesthesia, rCaIFN-γ was subcutaneously injected at a dose of 1×104U/kg body weight for the test group and physiologic saline was subcutaneously injected for the control group. Blood samples were collected 1h before P-I anesthesia (immediately before rCaIFN-γ injection) and 1 and 3h after anesthesia induction. NK cytotoxic activity was measured using the Rose Bengal assay, using canine thyroid adenocarcinoma cells as target cells. In the control group, NK cytotoxic activity decreased significantly over time (P<0.05). On the other hand, in the rCaIFN-γ group, the activity increased for the first hour after anesthesia induction without a significant difference from the level before anesthesia; furthermore, the activity at 3h after anesthesia induction was comparable with that before anesthesia. NK cytotoxic activity at 1 and 3h after anesthesia induction was significantly higher in the rCaIFNγ group than in the control group (P<0.05). Subcutaneous injection of rCaIFN-γ 1h before P-I general anesthesia not only maintained but also enhanced NK cytotoxic activity up to 3h after anesthesia induction in dogs. In conclusion, subcutaneous injection of rCaIFN-γ before cancer resection in cancer-bearing dogs might be effective for preventing intraoperative dissemination of cancer cells and postoperative cancer recurrence and metastasis.