Functional consequences of trogocytosis. Top: The “classical view” on trogocytosis assumes that membrane fragments including the immunological synapse (MHC molecules and costimulatory molecules; MHC and B7, pink) are exchanged with or acquired by T cells. “Trogocytic” acquisition of immune-related molecules on T cells (CD8 or CD4) may have the following functional consequences: (I) immune effector clearance by CD8 T cells via fratricide; (II) amplification of immune responses via acquisition of APC function by CD4 T cells (CD4 APC); (III) sustainment of immune responses by CD4 APC in the absence of APC. Lower part: The novel concept of trogocytosis as proposed by LeMaoult and colleagues assumes that the transfer of the immune-tolerogenic MHC molecule HLA-G—together with other molecules of the immunological synapse—provides a rapid “short distance” immune suppression. (I) In case of the immediate display, this suppressive function is exerted by the immunetolerogenic HLA-G molecule itself (immediate T-T suppression). (II) Trogocytosis of HLA-G induces the development of CD4 effector cells into HLA-G1 negative regulatory cells (CD4 HLA-G1⁻ Treg). These cells could have major impact in the immune regulation under physiological as well as pathological conditions (A, B, C). Illustration by Marie Dauenheimer.