Electron microscopy analysis of FcRγ localization after its capture by T cells by trogocytosis

T cells acquire various proteins from their cellular partners by the process of trogocytosis. We recently demonstrated that the FcγRIIIA receptor and its associated FcRγ are captured by T cells during their co-culture with FcγR-expressing target cells upon both antigen- or antibody-mediated stimulation. Interestingly, we found that FcR captured by T cells could bind ligands but did not transmit detectable intracellular signals or signaling-depending functions upon ligand binding suggesting their improper integration in the recipient T cell membrane. In this study, we provide morphological data in support of this hypothesis. Indeed, we show that the FcRγ-subunit, which we used as a fusion to GFP, was clearly present at the plasma membrane of donor cells, but was detected within structures that were in close contact of, but apparently not integrated in, the plasma membrane of recipient T cells.