Glutaurine enhances the depressed NK cell activity of tumor patients.

The effect of glutaurine, a newly discovered parathyroid substance, on human NK cell activity and on lymphocyte markers was studied. Both in vivo and in vitro treatment with glutaurine markedly enhanced the depressed natural lymphocytotoxicity of tumor patients without influencing their lymphocyte subpopulations. On the other hand it had no effect on the NK cell activity of healthy lymphocytes and of tumor patients' lymphocytes with originally "normal" NK activity. The NK-enhancing effect of glutaurine could not be explained by augmentation of the number of potential effector cells. It is suggested that glutaurine increases the originally low spontaneous killer activity of tumor patients' lymphocytes through an indirect regulatory mechanism.