Gell and Coombs classification of immune reactions

In allergy and immunology, as well as a broader range of medical conditions, the Gell and Coombs classification of immune reactions is widely used to categorized specific disorders into four useful categories. It has been improved, however, into subtypes and an additional type has been added.

• Type I, immediate hypersensitivity reactions, mediated by interaction of Immunoglobin E (IgE) antibody and antigen and release of histamine and other inflammatory cytokines
• 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
• type IV, cell-mediated hypersensitivity reactions, also delayed hypersensivity reaction or Cell mediated immunity, initiated by sensitized T-lymphocytes either by their releasing lymphokines or by T-cell–mediated cytotoxicity.