Role of the NK reaction in the diagnostics of liver and pancreas tumours.

The NK (natural killer) and K (killer) activities of peripheral lymphocytes were determined. The peripheral blood was obtained from healthy individuals and from patients with liver and pancreas diseases. Examinations were performed preoperatively. The natural cell-dependent cytotoxicity (NK) was examined against the K-562 cell line, while the antibody-dependent cellular cytotoxicity (ADCC) was examined against human red blood cells. The NK and K cell activities of the 19 patients with malignant tumours were substantially lower than those of the 40 healthy subjects. In the 12 cases of benign diseases of the liver and pancreas, however, the mean percentage cytotoxicity expressing the NK and K activities (40 +/- 10%) agreed with, or was higher than, the value for the controls (32 +/- 12%). Low cytotoxicity levels (12.6 +/- 5%) were characteristic in the malignant processes; in the majority of these, exploration showed local metastases or metastases besides the primary lesion. Since the NK and K cells play an essential role in the defence of the organism against tumours, the decrease in activity of this cell population may be of diagnostic value. In vitro interferon treatment in the control and benign cases considerably stimulated the NK reaction, and in some of the malignant diseases it raised the cytotoxicity values close to the control level.