Target cell ligands at the immunological synapse

"Target cell ligands at the immunological synapse" refers to a wide and heterogeneous group of molecules expressed on the surface of a target cell (such as an antigen-presenting cell, infected cell, or tumor cell) that interact with receptors on lymphocytes (like T cells, B cells, or natural killer cells) across the immunological synapse. Key classes of these ligands include major histocompatibility complex (MHC) molecules (presenting antigenic peptides), adhesion molecules (such as ICAM-1), costimulatory molecules (such as CD80 and CD86), as well as other immune checkpoint ligands (e.g., PD-L1, MICA/B, and others). The multiplicity and diversity of these ligands means the term does not refer to a specific entity but rather to the collective set of molecules mediating immune recognition, activation, and effector responses at the cell-cell junction known as the immunological synapse[2][5][3][4].