Modulation of natural killer cell activity by serum from cancer patients: preliminary results of a study of patients with colorectal adenocarcinoma or other types of cancer.

As previously reported for natural killer (NK) cells of normal individuals, prior incubation of peripheral blood lymphocytes from cancer patients with human normal serum or monomeric immunoglobulin G reduced their subsequent capacity to kill K562 target cells in a 4-h 51Cr release assay. The NK activity of such treated effector cells was significantly inhibited only by 58% of sera from patients with colorectal adenocarcinoma (21 of 36 cases) and by 67% of sera from patients with other lymphoid or nonlymphoid solid tumors (22 of 33 cases). The cytotoxic activity of cells previously incubated with eight noninhibitory sera was even augmented relative to medium-treated peripheral blood lymphocytes (control).