The natural killer activity (cytotoxicity) of lymphocytes.

The authors' own investigations into the spontaneous lymphocyte-mediated cytotoxicity (SLMC) have been reviewed and discussed in th light of literary data. It is suggested that SLMC is a resultant of complex effects contributed by antibodies present in the human serum and those attached to the surface of lymphocytes as well as by spontaneous (sui generis) functions of effector cells. The lymphocytes eliciting SLMC belong to the "O" subpopulation, bear Fc receptors and are presumably, identical with "K" lymphocytes. In animal experiments, the authors have shown that the SLMC reaction directed againt a virus-induced tumour is under polygenetic control primarily governed by gene(s0 linked to the histocompatibility region. In man, similarly as in the mouse, SLMC was found to be a genetically-controlled lymphocyte function in which gene(s) linked to the HLA-A2 B12 or the HLA-A3 B7 haplotype may play a determining role. The authors' clinical observations indicate that LSMC represents an important part of the defense mechanism against malignancies and autoimmune diseases. Estimation and follow-up of SLMC may be useful in monitoring the clinical course.