Hypersensitivity types
Type I - Allergy (immediate)
Type II - Cytotoxic, antibody-dependent
Type III - Immune complex disease
Type IV - Delayed-type hypersensitivity (Antibody Independant)
Type V - Autoimmune disease

Type II hypersensitivity
Classification and external resources
DiseasesDB	33482
MedlinePlus	000821
MeSH	D001327

In type II hypersensitivity (or cytotoxic hypersensitivity)^[1] the antibodies produced by the immune response bind to antigens on the patient's own cell surfaces. The antigens recognized in this way may either be intrinsic ("self" antigen, innately part of the patient's cells) or extrinsic (absorbed onto the cells during exposure to some foreign antigen, possibly as part of infection with a pathogen). These cells are recognized by macrophages or dendritic cells which act as antigen presenting cells, this causes a B cell response where antibodies are produced against the foreign antigen.

An example here is the reaction to penicillin where the drug can bind to red blood cells causing them to be recognised as different, B cell proliferation will take place and antibodies to the drug are produced. IgG and IgM antibodies bind to these antigens to form complexes that activate the classical pathway of complement activation to eliminate cells presenting foreign antigens (which are usually, but not in this case, pathogens). That is, mediators of acute inflammation are generated at the site and membrane attack complexes cause cell lysis and death. The reaction takes hours to a day.

Another form of type II hypersensitivity is called antibody-dependent cell-mediated cytotoxicity (ADCC). Here, cells exhibiting the foreign antigen are tagged with antibodies (IgG or IgM). These tagged cells are then recognised by natural killer (NK) cells and macrophages (recognised via IgG bound (via the Fc region) to the effector cell surface receptor, CD16 (FcγRIII)), which in turn kill these tagged cells.

[edit] Some examples

Disease	Target antigen	Pathophysiology	Main effects
Autoimmune hemolytic anemia	Rh antigens, I antigen on RBCs	Opsonization and phagocytosis of erythrocytes	Hemolysis Anemia
Hemolytic disease of the newborn (HDN) * (erythroblastosis fetalis)	Antigens on erythrocytes	RBS degradation	Reticulocytosis Anemia
Autoimmune thrombocytopenic purpura	Glycoprotein IIb/IIIa on platelets	Opsonization and phagocytosis of platelets	Bleeding diathesis
Pemphigus vulgaris	Epidermal cadherins	Activation of proteases Disruption of cell adhesion molecules	Bullae
ANCA-associated vasculitides	Neutrophil granule proteins	Neutrophil degranulation and inflammation	Vasculitis
Goodpasture's syndrome	Noncollagenous protein	Complement and Fc-receptor-mediated inflammation	Nephritis Lung hemorrhage
Acute rheumatic fever	M proteins on Group A streptococci and then myocardial antigen	Macrophage activation Inflammation	Myocarditis Arthritis
Myasthenia gravis	Acetylcholine receptor	Competitive acetylcholine inhibition Receptor down-regulation	Muscle weakness Paralysis
Graves disease	TSH receptor	Receptor agonism	Hyperthyroidism
Pernicious anemia (if autoimmune)	Intrinsic factor on gastric parietal cells	Decreased vitamin B12 absorption	Abnormal erythropoiesis Anemia
Unless else specified in boxes, then ref is: [2] * - HDN not taken from [2]

Other examples are:

• Transfusion reactions
• Acute transplant rejection

[edit] References

v • d • e Immune disorders: hypersensitivity and autoimmune diseases Type I/allergy/atopy (IgE) Foreign Atopic dermatitis · Allergic urticaria · Hay fever · Allergic asthma · Anaphylaxis · Food allergy (Milk, Egg, Peanut, Tree nut, Seafood, Soy, Wheat), Penicillin allergy Autoimmune none Type II/ADCC (IgM, IgG) Foreign Pernicious anemia · Hemolytic disease of the newborn Autoimmune Cytotoxic Autoimmune hemolytic anemia · Idiopathic thrombocytopenic purpura  · Bullous pemphigoid  · Pemphigus vulgaris · Rheumatic fever · Goodpasture's syndrome "Type 5"/receptor Graves' disease · Myasthenia gravis Type III (Immune complex) Foreign Henoch-Schönlein purpura · Hypersensitivity vasculitis · Reactive arthritis · Rheumatoid arthritis · Farmer's lung · Post-streptococcal glomerulonephritis · Serum sickness · Arthus reaction Autoimmune Systemic lupus erythematosus · Subacute bacterial endocarditis Type IV/cell-mediated (T-cells) Foreign Contact dermatitis · Mantoux test Autoimmune Diabetes mellitus type 1 · Hashimoto's thyroiditis · Guillain–Barré syndrome  · Multiple sclerosis  · Coeliac disease · Giant cell arteritis GVHD Transfusion-associated graft versus host disease Unknown/ multiple Foreign Hypersensitivity pneumonitis (Allergic bronchopulmonary aspergillosis) · Transplant rejection · Latex allergy (I+IV) Autoimmune Sjögren's syndrome · Autoimmune hepatitis · Autoimmune polyendocrine syndrome (APS1, APS2) · Autoimmune adrenalitis lymphocyte navs: cells/physio, immunodeficiency/immunoproliferative immunoglobulin/neoplasia, proc