Natural killer activity in patients with biopsy-proven liver disease.

Most previous studies of lymphocyte-mediated cytotoxicity to animal and human hepatocytes have not taken into account the ability to human lymphoid cells to kill spontaneously cultured cell lines, particularly those of malignant origin (the natural killer or NK effect). We have studied spontaneous killing to a human target (erythromyeloid cell line K562) in patients with biopsy-proven liver disease and from normal controls. Patients with chronic active hepatitis were shown to have a significant reduction in NK activity unrelated to immunosuppressive therapy (P less than 0.01). Other groups showed normal values. These results imply that cytotoxic effectors reported active in chronic liver disease are K cells and not NK cells, with which they share many characteristics, and suggest that a cytotoxic mechanism considered to be of importance in immunosurveillance may be reduced in chronic aggressive hepatitis.