13167 IUPAC Gold Book - Gell and Coombs classification 10.1351/goldbook.13167 13167 current 1 Classification of immune mechanisms of tissue injury into four types: type I, immediate-type hypersensitivity reactions, mediated by interaction of immunoglobulin E (IgE) antibody and antigen causing the release of histamine and other mediators; type II, antibody-mediated hypersensitivity reactions, due to antibody–antigen interactions on cell surfaces; type III, immune complex, local or general inflammatory responses due to formation of circulating immune complexes and their deposition in tissues; and type IV cell-mediated hypersensitivity reactions, initiated by sensitized T lymphocytes either by release of lymphokines or by T-cell-mediated cytotoxicity [see cytotoxic T lymphocyte (CTL)]. T lymphocytes https://goldbook.iupac.org//terms/view/13724 cytotoxic T lymphocyte (CTL) https://goldbook.iupac.org//terms/view/13072 hypersensitivity https://goldbook.iupac.org//terms/view/13241 immediate-type hypersensitivity https://goldbook.iupac.org//terms/view/13255 immune complex https://goldbook.iupac.org//terms/view/13257 immunoglobulin E (IgE) https://goldbook.iupac.org//terms/view/13288 lymphokines https://goldbook.iupac.org//terms/view/13415 PAC, 2012, 84, 1113. 'IUPAC glossary of terms used in immunotoxicology (IUPAC Recommendations 2012)' on page 1168 (https://doi.org/10.1351/PAC-REC-11-06-03) https://goldbook.iupac.org/terms/view/13167/html https://goldbook.iupac.org/terms/view/13167/json https://goldbook.iupac.org/terms/view/13167/plain Citation: 'Gell and Coombs classification' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.13167 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-07-14T09:14:17+00:00