Chapter 28: Classification of hypersensitivity reactions.
The original Gell and Coomb's classification categorizes hypersensitivity reactions into four subtypes according to the type of immune response and the effector mechanism responsible for cell and tissue injury: type I, immediate or IgE mediated; type II, cytotoxic or IgG/IgM mediated;  type III, IgG/IgM immune complex mediated; and type IV, delayed-type hypersensitivity or T-cell mediated. The classification has been improved so that type IIa is the former type II and type IIb is antibody-mediated cell stimulating (Graves Disease and the "autoimmune" type of  chronic idiopathic urticaria). Type IV has four major categories: type IVa is CD4(+)Th1 lymphocyte mediated with activation of macrophages (granuloma formation and type I diabetes mellitus); type IVb is CD4(+)Th2 lymphocyte mediated with eosinophilic involvement (persistent  asthma and allergic rhinitis); type IVc is cytotoxic CD8(+) T lymphocyte with involvement of perforin-granzme B in apoptosis (Stevens-Johnson syndrome and toxic epidermal necrolysis); type IVd is T-lymphocyte-driven neutrophilic inflammation (pustular psoriasis and acute generalized  exanthematous pustulosis). Some diseases have multiple types of immunologic hypersensitivity.
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D000920:Antibody-Dependent Cell Cytotoxicity / Q000276:immunology; D006801:Humans; D006967:Hypersensitivity / Q000145:classification* / Q000276:immunology; D006968:Hypersensitivity, Delayed / Q000276:immunology; D006969:Hypersensitivity, Immediate / Q000276:immunology; D007105:Immune Complex Diseases / Q000276:immunology