Colon cancer cells acquire immune regulatory molecules from tumor-infiltrating lymphocytes by trogocytosis

Significance We have identified the presence of cancer cells harboring immune cell–specific surface marker proteins such as CD4 in the tumor microenvironment. Cancer cells acquired not only the T cell marker protein CD4 but also immune regulatory molecules such as CTLA4 by trogocytosis. Unlike other endocytic mechanisms, trogocytosis maintains the cellular localization and functions of the transferred membrane proteins. Therefore, trogocytic transfer of immune regulatory molecules enhances the immunosuppressive functions of cancer cells. This study provides insight into the interactions between cancer cells and tumor-infiltrating immune cells and how they contribute to the development of the immunosuppressive tumor microenvironment.