ANALYSIS OF NATURAL KILLER ACTIVITY OF HUMAN LARGE GRANULAR LYMPHOCYTES AT A SINGLE CELL LEVEL

Abstract

This chapter reviews natural killer (NK) activity of human large granular lymphocytes (LGLs) at a single cell level. LGLs comprise approximately 10% of peripheral blood lymphoid cells, and they can be enriched up to ≥ 90% purity by discontinuous density gradient centrifugation and subsequent depletion of high-affinity sheep erythrocyte rosette-forming cells from low density, LGL-enriched populations. In a study described in the chapter, the single-cell cytotoxicity assay in agarose was used to estimate the frequency of LGL capable of binding and lysing NK-sensitive target cells. The results indicate that up to 70% of LGL are NK cells. An additional parameter that affects the lytic potential of killer cells is their recycling capacity. It was demonstrated in another study described in the chapter, by using density gradient-purified LGL-target cell conjugates, that recycling is involved in NK lysis. It was shown that interferon can augment all of the above mentioned phases of NK cell-mediated cytotoxicity. The data obtained do not indicate that LGL are a homogenous subpopulation of lymphoid cells. On the contrary, about 20–30% of them have no detectable NK activity, there is a clear size and density heterogeneity among LGL, and they are antigenically heterogeneous.