title: Evolving concepts of specificity in immune reactions.
abstract: Our goal is to provide a perspective on current understanding of the origins of specificity in immune reactions, a topic that has intrigued scientists for over a century. A fundamental property of adaptive immune responses is the ability to discriminate among an immense variety of substances by means of antibodies (Abs) and Ab-like receptors on T lymphocytes [T-cell receptors (TCRs)], each able to bind a particular chemical structure [the antigen (Ag)] and not, or only weakly, similar alternatives. Evidence has long existed, however, and has grown, especially recently, that while exhibiting remarkable specificity, many individual Abs and TCRs can also bind a variety of very different ligands. How can Ag recognition by these receptors exercise the great specificity for which they are renowned and yet react with a variety of different ligands (degeneracy)? We critically consider the mechanistic bases for this specificity/degeneracy enigma and also compare and contrast Ag recognition by Abs and TCRs.
authors.affiliation: Koch Institute for Integrative Cancer Research, and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. hneisen@mit.edu
authors.forename: Herman N
authors.initials: HN
authors.lastname: Eisen
authors.forename: Arup K
authors.initials: AK
authors.lastname: Chakraborty
mesh_terms: D056704:Adaptive Immunity / Q000276:immunology*; D000818:Animals; D000918:Antibody Specificity / Q000276:immunology*; D017951:Antigen Presentation / Q000276:immunology; D000941:Antigens / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D006801:Humans; D007239:Infections / Q000276:immunology*; D018448:Models, Immunological; D011948:Receptors, Antigen, T-Cell / Q000276:immunology* / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism
chemical_list: D000941:Antigens; D018984:Epitopes, T-Lymphocyte; D011948:Receptors, Antigen, T-Cell