NK and K cell activity of human blood: differences according to sex, age, and disease.

We report a study on the activity of NK cells ('natural' killer cells) and K cells (antibody-dependent killer cells) in human peripheral blood in health and disease. The 'targets' used were cells of the Chang cell-line, sensitised with rabbit anti-Chang cell antibody for K cell activity, and killing was assessed by release of radiochromium at effector: target ratios of 50:1 and 100:1. The positive findings were that NK cell activity, but not K cell activity, was greater in males and in youth, that NK cell activity was reduced in systemic lupus erythematosus, that neither NK nor K cell activity was altered in rheumatoid arthritis, and that K cell activity was reduced in chronic active hepatitis.