Ca2+ signals:
Molecular Mechanisms and Integrative Functions Collaborative Research Center 894

Project A1 - Markus Hoth

Ca2+-dependent CTL and NK cell cytotoxicity

Killing cancer cells is one important function of cytotoxic T lymphocytes (CTL) and natural killer (NK) cells.

We have shown that an individual primary human CTL or NK cell can kill clonal cancer (= target) cells by apoptosis or necrosis, and often switches between both modes. We found that Ca2+ signals in NK cells are different for both modes and that Ca2+ influx across the plasma membrane modulates the cytotoxicity (= killing) efficiency of CTL and NK cells.

We will perform a detailed analysis of Ca2+ signals in primary human CTL and NK cells during apoptotic and necrotic target cell killing to test if potential differences in Ca2+ signaling determine the relative contribution of each killing type and its killing efficiency. Based on our additional finding that the Ca2+ dependence of the perforin-mediated necrotic target cell killing is different for CTL and NK cells, we will compare the molecular mechanisms of perforin-mediated cell death in both cell types.

In general, the analysis of primary human cells is limited to in vitro assays. To mimic the in vivo situation more closely, we have developed 2-dimensional (2D) and 3-dimensional (3D) extracellular matrix-based assays for cytotoxicity analysis.

We will further optimize these assays and quantify Ca2+-dependent target cell killing by CTL and NK cells under these conditions.