Human γδ T lymphocytes strip and kill tumor cells simultaneously

When human γδ lymphocytes bind to tumor cells for killing, they also strip their membrane for unknown reasons. Here we investigated this topic using the model of human γδ lymphocytes co-incubated with anaplastic large cell lymphomas, a group of tumors with cytolytic T or null lineage. By using flow cytometry and live cell imaging, we show that as soon as both cells were in contact, the TCR-mediated activation of γδ lymphocytes simultaneously triggered their secretion of lytic granules and stripping of lymphoma cell membranes, and both activities continued even after their cell death. However reciprocally in such conjugates, resistant lymphoma failed to strip γδ cells and to kill them by untargeted secretion of their own lytic granules. This indicated that secretion of lytic granules and target membrane stripping are associated in lytic cell conjugates, and that γδ T lymphocytes strip and kill their targets simultaneously.