Multiple cell surface proteins on immune and tissue cells

This entry encompasses **hundreds to thousands of individual cell-surface proteins** expressed on immune cells (e.g., T cells, B cells, dendritic cells, macrophages, NK cells) and on tissue-resident cells. These proteins include **receptors (e.g., immune checkpoints like PD-1, adhesion molecules like integrins, costimulatory proteins, MHC complexes, and a wide array of immunoglobulin superfamily members)**[4][1][5][9]. Each cell type and tissue expresses a distinct pattern ("surfaceome") of proteins that determines both cellular identity and functional role in health and disease[2][9]. Therapeutic agents target specific cell-surface proteins to modulate immune responses or to eliminate pathological cells, but deliberate precision is required owing to their presence on multiple cell types and associated risk of unintended effects. This term does **not specify a single therapeutic target**, molecular family, or drug mechanism—and as such is *inappropriate* for structured pharmacological or biomarker mapping. In summary: The phrase "multiple cell surface proteins on immune and tissue cells" is too generic, not a canonical molecular target, and should be replaced by specific protein names (e.g., "Programmed death-1 receptor" (PD-1), "Cluster of Differentiation 20" (CD20), "Major histocompatibility complex class I"), accompanied by their well-defined functions, roles, and therapeutic relevance[5][4][1][9][2].