Membrane redistributions through multi-intercellular exchanges and serial trogocytosis.

Trogocytosis is a rapid transfer between cells of membranes and associated proteins. Trogocytic exchanges have been investigated between different cell types, mainly in two-cell systems, involving one donor and one acceptor cell type. Here, we studied trogocytosis in a more complex system, involving not only several immune cell subsets but also multiple tumor cells. We show that CD4(+) T cells, CD8(+) T cells and monocytes can acquire membrane patches and the intact proteins they contain from different tumor cells by multiple simultaneous trogocytoses. The trogocytic capabilities of CD4(+) and CD8(+) T cells were found to be similar, but inferior to that of autologous monocytes. Activated peripheral-blood mononuclear cells (PBMCs) may also exchange membranes between themselves in an all-autologous system. For this reason, monocytes are capable of acquiring membranes from multiple tumor cell sources, and transfer them again to autologous T cells, along with some of their own membranes (serial trogocytosis). Our data illustrate the extent of membrane exchanges between autologous activated immune effector cells and their environment, and how the cellular content of the local environment, including "bystander" cells, may impact the functions of immune effector cells.