Type I Hypersensitivity: IgE-mediated reactions
Type II Hypersensitivity: :Antibody-mediated Cytotoxicity
- Results when IgG or IgM bing do cell surface Ag
– Activating Complement
– Binding Fc receptors on Tc cells promoting Antibody-Dependent Cell-mediated Cytotoxicity (ADCC)
- Both processes result in lysis of the Ab-coated cell
- Clinical examples of Type II responses include:
– Certain autoimmune diseases
Autoimmune hemolytic anemia
– Hemolytic Disease of the Newborn
– Hyperacute graft rejection
Blood Transfusion reactions
Type III Hypersensitivity:Immune Complex-mediated cytotoxicity
- Directed against soluble antigens caused by the deposition of
antigen/antibody complexes in tissue and blood vessels.
- The complexes activate complement and attract ploymorphs and
macrophages to the site.
- These cells may exocytose their granule contents and release reactive
oxygen and nitrogen intermediates to cause local tissue damage.
Type IV Hypersensitivity:Delayed-type hypersensitivity