INTRODUCTION TO NK ACTIVITY TEST

Decreased Natural killer cell activity (NKA) for interferon-gamma production (NKA-IFNγ) has been reported in cancer patients. The aim of this study was to determine the diagnostic performance of NKA-IFNγ for gastric cancer (GC). Results NKA-IFNγ levels were decreased in 261 GC patients with all stages of tumor compared to those in 48 healthy donors (P < 0.001), and lower levels of NKA-IFNγ were associated with higher GC stages. NKA-IFNγ levels were also associated with clinicopathological parameters including tumor size, depth of invasion, and lymph node metastasis. NKA-INFγ assay had better diagnostic value (AUC = 0.822) compared to serum CEA (0.624) or CA19-9 assay (0.566) (P < 0.001). Using different cut-off levels, serum CEA and CA19-9 showed sensitivities of 6.1-14.2% and 4.2-28.0%, respectively, which were much lower than that of NKA-IFNγ (55.6-66.7%). Methods This study included 261 patients with newly diagnosed GC and 48 healthy donors. NKA for IFNγ was determined by enzyme immunoassay after incubation of whole blood, and diagnostic performance was evaluated. Conclusions NK cell activities for IFNγ production could be used as a supportive non-invasive tumor marker for GC diagnosis.