Natural killer cell activity and recycling capacity of natural killer cells in patients with carcinoma of the prostate.

Natural killer (NK) cell activity and recycling capacity of NK cells in patients with carcinoma of the prostate (CaP) was determined by combining the 51Cr-release cytotoxicity assay and single cell cytotoxicity assay in agarose. The NK cell activity in patients with advanced CaP (stage D) was significantly lower than the NK cell activity of normal controls and that of patients with localized CaP (stage B and C). The number of active NK cells in the peripheral blood lymphocytes was similar in all groups tested including normal controls, patients with localized CaP, and patients with advanced CaP. Maximal killing potential (Vmax) and maximal recycling capacity (MRC) were significantly reduced in patients with advanced CaP as compared to patients with localized CaP or normal controls. Obtained results indicated that the depressed NK cell activity in advanced CaP was not due to a reduced number of active NK cells but due to the decreased recycling capacity of the individual NK cells.