Peptide antigen

A peptide antigen is a **short linear fragment of amino acids derived from a protein antigen** that can stimulate an immune response when presented on the surface of cells, typically by major histocompatibility complex (MHC) molecules[1][3][8]. Peptide antigens are recognized by T cell receptors and are central to the mechanisms of adaptive immunity. They can originate from pathogens, tumors, or host proteins and are critical in vaccine development, immunotherapy, and studies of autoimmune disease[1][2][8]. However, “peptide antigen” is not a single molecular entity or a defined therapeutic target but a category of molecules defined by function; the specific antigenic peptide will vary depending on the source protein and the individual’s MHC genotype. As such, "peptide antigens" is a **broad class of immune system ligands** and not a precise, canonically named molecular target[1][3][6]. **Note:** - "Peptide antigens" is not a specific receptor, enzyme, or protein, but rather refers to a class of molecules; it cannot be mapped to a single canonical molecular target[1][3][6]. - The entry is *incorrect* as a therapeutic target in the context of precise biomedical target annotation, since it is not a druggable protein, gene, or well-defined structure. Instead, it should be specified more precisely as an individual peptide–MHC complex, or as a particular epitope of interest, e.g., a specific viral or tumor antigenic peptide[1][3][8]. **For structured databases, this entry should be flagged as too broad/non-specific and not a valid canonical drug target.**

Other names

antigenic peptideimmunopeptide

Antigen presentation by MHC for T cell recognition Induction of immunogenic or tolerogenic responses