[Natural killer (NK) activity of peripheral blood and regional lymph nodes in patients with genitourinary malignant tumors. 1. NK activity of peripheral blood in patients with genitourinary malignant tumors].

51Cr-release assay is a popular method to measure the cytotoxicity of natural killer cells, so-called NK activity, but this assay includes trouble-some steps and management because of using radioisotope (RI) reagent. ATP-chemiluminescence assay (ATP assay), a new method, does not require RI. This assay measures intracellular adenosintriphosphate (ATP) volume by Luciferin-Luciferase reaction. In the research for this paper, the NK activity in 40 healthy donors, 40 patients with urological benign diseases and 39 patients with malignant tumors was measured by both 51Cr-release and ATP assay. The values obtained by these two methods showed a high correlation (r = 0.78). And the NK activity in patients with malignant tumors was lower in high stage patients than it was in low stage patients. These results proposed that ATP assay would be more suitable than 51Cr-release assay for measuring not only NK activity but also the other cytotoxic tests, because ATP is present only in living cells and that, in patients with genitourinary malignant tumors, NK activity of peripheral blood would be a useful tumor marker.