Trogocytosis is the exchange of membrane-associated molecules between cells, which can either enhance or suppress immune responses. However, the mechanisms that regulate trogocytosis in T cells and its resulting effects remain unclear. Recently,Stefano Barbera’s study shows that T cells can transfer chimeric antigen receptors (CARs) through trogocytosis, effectively "arming" recipient T cells to respond to tumor antigens. This process leads to the upregulation of proteins associated with cytotoxic responses and the killing of target cells. They also demonstrate that while trogocytosis requires cell-cell contact, the exchange of specific membrane proteins does not depend on a cognate binding partner on the recipient cell's surface. Instead, the likelihood of a protein being exchanged is determined by its transmembrane domain. These findings provide new insights into how trogocytosis can be modulated, particularly in CAR-T cell therapies.

CAR-T cells can transfer Thy1.1 to other immune cells

CARs are trogocytosed to other T cells

CAR and TCR recipient T cells acquire the ability to respond to tumor antigens

TM domains dictate protein exchange between T cells

While they have clarified the mechanism by which molecules are selected for trogocytosis, our study provides limited insight into the impact of CAR-armed recipient cells in the context of cancer. Further research using more advanced preclinical mouse models is needed to better understand how the trogocytosis of CAR molecules influences the antitumor response and the tumor microenvironment. Additionally, although they have demonstrated that trogocytosis of clinically relevant CARs can occur between human T cells, the full implications of this phenomenon in clinical settings remain to be explored.