Target-induced natural killer cell loss as a measure of NK cell responses.

The interaction of natural killer cells with susceptible target cells triggers NK cell activation, eliciting not only NK cell cytotoxicity and cytokine secretion, but also NK cell death. This study shows that following target cell interaction there is a substantial loss of NK cells, the extent of which correlates with measures of NK cell cytotoxicity assessed by the target cell release of (51)Cr and by the externalisation of the lysosomal marker LAMP-1 (CD107a) which is assessed on the remaining NK cells. This is the case for the killing of K562 (natural killing) and the CD20 mAb (Rituximab)-mediated killing of RAJI cells and autologous B cells (antibody-dependent cell cytotoxicity). This target-induced NK loss (TINKL) provides a sensitive and specific measure of NK cell responses appropriate to a clinical laboratory setting.