Lymphocytes and Trogocytosis-Mediated Signaling

Abstract

Trogocytosis is the intercellular transfer of membrane and membrane-associated molecules. This underappreciated process has been described in a variety of biological settings including neuronal remodeling, fertilization, viral and bacterial spread, and cancer, but has been most widely studied in cells of the immune system. Trogocytosis is performed by multiple immune cell types, including basophils, macrophages, dendritic cells, neutrophils, natural killer cells, B cells, γδ T cells, and CD4+ and CD8+ αβ T cells. Although not expressed endogenously, the presence of trogocytosed molecules on cells has the potential to significantly impact an immune response and the biology of the individual trogocytosis-positive cell. Many studies have focused on the ability of the trogocytosis-positive cells to interact with other immune cells and modulate the function of responders. Less understood and arguably equally important is the impact of these molecules on the individual trogocytosis-positive cell. Molecules that have been reported to be trogocytosed by cells include cognate ligands for receptors on the individual cell, such as activating NK cell ligands and MHC:peptide. These trogocytosed molecules have been shown to interact with receptors on the trogocytosis-positive cell and mediate intracellular signaling. In this review, we discuss the impact of this trogocytosis-mediated signaling on the biology of the individual trogocytosis-positive cell by focusing on natural killer cells and CD4+ T lymphocytes.

The role of endocytic trafficking in antigen T cell receptor activation

“…Trogocytosis was first described as a mechanism for lymphocytes to retrieve plasma membrane from APC and was considered to be antigen receptor specific [ 63 ]. Later on, trogocytosis was attributed also to other cell types, including non-immune cells [ 64 ] and it has been proposed that it is a bidirectional mechanism in which both cells involved exchange plasma membrane domains [ 65 ]. Using cell surface markers and flow cytometry, plasma membrane exchange has been observed even in the absence of TCR-MHC interaction [ 66 ].…”

“…Using chemical inhibitors, trogocytosis was shown to depend on Src, Syk and PI3K kinase activities [ 51 , 64 , 67 , 68 ], actin-polymerization and, in some conditions, on microtubule motility [ 67 ]. However, the best experimental setting to investigate the impact of trogocytosis on T cell function is the inactivation of molecular factors involved in this process.…”

NK Cells Acquire CCR5 and CXCR4 by Trogocytosis in People Living with HIV-1

“…During steady states as well as in acute viral infections, NK cells are thought to constantly interact with their neighboring cells within the tissue microenvironment or in circulation via a wide range of receptors and adhesion molecules expressed on their surface [ 1 , 2 , 3 ]. As a consequence, these close-range contacts between NK cells and their targets often results in passive or active transferring of membrane patches and other surface molecules from the target cells into the effector (NK) cells [ 4 ], a process called trogocytosis [ 5 , 6 ]. Trogocytosis is a process firstly described and widely observed in other lymphocytes including B and T cells [ 5 ].…”

“…Trogocytosis is a process firstly described and widely observed in other lymphocytes including B and T cells [ 5 ]. The potential trogocytosis between HIV-1-infected cells and NK cells, as well as its physiological consequence, has not been described, and very little is known regarding other immune cells [ 6 , 7 ].…”

Impact of Graft-Resident Leucocytes on Treg Mediated Skin Graft Survival

“…in 2004 where cross-dressing of DCs with donor MHC was described as a third pathway of allo-recognition, termed the “semi-direct” pathway ( 13 ). This pathway of acquired absorption of intact MHC-bearing membrane vesicles is now termed trogocytosis ( 14 ) and dates back to studies on cell-membrane exchange in the 1970s ( 15 ).…”