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Hypersensitivity Reactions

  • Although immune responses are required for protection against foreign microbes, excessive activation of immune mechanisms can cause profound host tissue damage. Immune-mediated processes of host tissue injury, which have been historically termed "Hypersensitivity Reactions", can be classified according to four subtypes which highlight their basic mechanisms. However, during any complex disease pathology any combination or all may be occurring at once. Types I, II, and III all involve Antibody-mediated injury while in Type IV Hypersensitivity injury is T-cell-mediated.
Hypersensitivity Subtypes