antigen binding https://github.com/geneontology/go-ontology/issues/25644 major histocompatibility complex activity molecular_function Binding to an antigen, any substance which is capable of inducing a specific immune response and of reacting with the products of that response, the specific antibody or specifically sensitized T-lymphocytes, or both. Binding may counteract the biological activity of the antigen. Antigen binding by an MHC protein complex allows the antigen to be displayed to a T cell or NK cell. opsonin activity antibody activity GO:0003823 MHC activity B cell receptor activity major histocompatibility complex antigen display activity binding