(IM09) Assessment of NK Cell Activity for Immunity Evaluation in Dogs

Abstract: Natural Killer (NK) cell activity is crucial for immunity because NK cells can directly eliminate virus-infected and tumor cells without prior sensitization, providing rapid immune defense. Additionally, they produce cytokines like IFNγ, which enhance adaptive immune responses by promoting macrophage activation and antigen presentation. This study aimed to assess NK cell activity in dogs by measuring plasma IFNγ levels after stimulation with NK cell stimulating agent (Promoca, NKMAX). A total of 120 dogs were included, and 1 ml of whole blood was collected from each. The blood was incubated with Promoca at 37°C for 24 hours, followed by centrifugation to obtain plasma. IFNγ concentrations were measured using an ELISA kit. The median plasma IFNγ level was 621.8 pg/ml. Healthy dogs exhibited a median level of 1084.9 pg/ml (n=53), whereas diseased dogs showed a lower level of 559.5 pg/ml (n=67). Notably, dogs with tumors had a significantly reduced median IFNγ level of 125.6 pg/ml (n=17). Age also influenced IFNγ levels, with younger dogs (< 7 years) showing higher levels (median: 928.9 pg/ml, n=28) compared to older dogs (≥7 years, median: 590.25 pg/ml, n=92). These findings suggest that measuring NK cell activity through IFNγ levels may serve as a useful biomarker for canine immune function. The significant differences observed between healthy and diseased dogs, particularly in tumor-bearing individuals, highlight the potential clinical utility of this test. Further research is needed to validate its application in veterinary medicine.