In type II hypersensitivity (or cytotoxic hypersensitivity) 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 (adsorbed onto the cells during exposure to some foreign antigen, possibly as part of infection with a pathogen). These cells are recognized by macrophage

Macrophage

Macrophages are cells produced by the differentiation of monocytes in tissues. Human macrophages are about in diameter. Monocytes and macrophages are phagocytes. Macrophages function in both non-specific defense as well as help initiate specific defense mechanisms of vertebrate animals...

s or dendritic cell

Dendritic cell

Dendritic cells are immune cells forming part of the mammalian immune system. Their main function is to process antigen material and present it on the surface to other cells of the immune system. That is, dendritic cells function as antigen-presenting cells...

s, which act as antigen-presenting cells. This causes a B cell

B cell

B cells are lymphocytes that play a large role in the humoral immune response . The principal functions of B cells are to make antibodies against antigens, perform the role of antigen-presenting cells and eventually develop into memory B cells after activation by antigen interaction...

 response, wherein antibodies are produced against the foreign antigen.

An example of type II hypersensitivity is the reaction to penicillin wherein the drug can bind to red blood cells, causing them to be recognized as different; B cell proliferation will take place and antibodies to the drug are produced. IgG and IgM

IGM

IGM as an acronym or abbreviation can refer to:* Immunoglobulin M , the primary antibody against A and B antigens on red blood cells* International Grandmaster, a chess ranking* intergalactic medium* Intragroup medium - see: Intracluster medium...

 antibodies bind to these antigens to form complexes that activate the classical pathway

Classical complement pathway

The Classical pathway of activation of the complement system is a group of blood proteins that mediate the specific antibody response. The main activators of the Classical Pathway are antigen-antibody complexes.-Initiation:...

 of complement

Complement system

The complement system helps or “complements” the ability of antibodies and phagocytic cells to clear pathogens from an organism. It is part of the immune system called the innate immune system that is not adaptable and does not change over the course of an individual's lifetime...

 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 complex

Complement membrane attack complex

The membrane attack complex is typically formed on the surface of intruding pathogenic bacterial cells as a result of the activation of the alternative pathway of the complement system, and it is one of the effector proteins of the immune system. The membrane-attack complex forms transmembrane...

es cause cell lysis

Lysis

Lysis refers to the breaking down of a cell, often by viral, enzymic, or osmotic mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a "lysate"....

 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

CD16

CD16 is a low affinity Fc receptor.It is a cluster of differentiation found on the surface of natural killer cells, neutrophil polymorphonuclear leukocytes, monocytes and macrophages...

 (FcγRIII)), which in turn kill these tagged cells.

Some examples

Disease	Target antigen	Pathophysiology	Main effects
Autoimmune haemolytic anemia	Rh antigens Rhesus blood group system The Rh blood group system is one of thirty current human blood group systems. Clinically, it is the most important blood group system after ABO. At Present, the Rh blood group system consists of 50 defined blood-group antigens, among which the 5 antigens D, C, c, E, and e are the most important... , I antigen on RBC Red blood cell Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system... s	Opsonization and phagocytosis of erythrocytes	Hemolysis Hemolysis Hemolysis —from the Greek meaning "blood" and meaning a "loosing", "setting free" or "releasing"—is the rupturing of erythrocytes and the release of their contents into surrounding fluid... Anemia Anemia Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
Hemolytic disease of the newborn Hemolytic disease of the newborn Hemolytic disease of the newborn, also known as hemolytic disease of the fetus and newborn, HDN, HDFN, or erythroblastosis fetalis, is an alloimmune condition that develops in a fetus, when the IgG molecules produced by the mother pass through the placenta...  (HDN) * (erythroblastosis fetalis)	Antigens on erythrocytes	Red blood cell Red blood cell Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...  degradation	Reticulocytosis Reticulocytosis Reticulocytosis is a condition where there is an increase in reticulocytes, immature red blood cell.It is commonly seen in Anemia. They are seen on blood films when the bone marrow is highly active in an attempt to replace red blood cell loss such as in haemolytic anaemia, haemorrhage.-External... Anemia Anemia Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
Autoimmune thrombocytopenic purpura	Glycoprotein IIb/IIIa Glycoprotein IIb/IIIa In medicine, glycoprotein IIb/IIIa is an integrin complex found on platelets. It is a receptor for fibrinogen and aids in platelet activation. The complex is formed via calcium-dependent association of gpIIb and gpIIIa, a required step in normal platelet aggregation and endothelial adherence...  on platelets	Opsonization and phagocytosis of platelets	Bleeding diathesis
Pemphigus vulgaris Pemphigus vulgaris Pemphigus vulgaris is a chronic blistering skin disease with skin lesions that are rarely pruritic, but which are often painful.-Pathophysiology:...	Epidermal cadherin Cadherin Cadherins are a class of type-1 transmembrane proteins. They play important roles in cell adhesion, ensuring that cells within tissues are bound together. They are dependent on calcium ions to function, hence their name.The cadherin superfamily includes cadherins, protocadherins, desmogleins, and... s	Activation of proteases Disruption of cell adhesion molecule Cell adhesion molecule Cell Adhesion Molecules are proteins located on the cell surface involved with the binding with other cells or with the extracellular matrix in the process called cell adhesion.... s	Bullae
ANCA-associated vasculitides ANCA-associated vasculitides ANCA-associated vasculitides are diseases caused by vasculitis in which antineutrophil cytoplasmic antibodies can be detected in the blood.-Types:Three main AAVs are Churg-Strauss syndrome, microscopic polyangiitis and Wegener's granulomatosis...	Neutrophil granule proteins	Neutrophil degranulation and inflammation	Vasculitis
Goodpasture's syndrome Goodpasture's syndrome Goodpasture’s syndrome is a rare disease characterized by glomerulonephritis and hemorrhaging of the lungs...	non-collagenous domain (NC1) of the alpha-3 chain of collagen type IV	Complement Complement receptor A complement receptor is a receptor of the complement system, a part of the mediated innate immune system. Complement receptors are responsible for detecting pathogens by mechanisms not mediated by antibodies. Complement activity is not antigen sensitive, but can be triggered by specific antigens...  and Fc-receptor-mediated inflammation	Nephritis Nephritis Nephritis is inflammation of the nephrons in the kidneys. The word "nephritis" was imported from Latin, which took it from Greek: νεφρίτιδα. The word comes from the Greek νεφρός - nephro- meaning "of the kidney" and -itis meaning "inflammation".... Lung hemorrhage
Acute rheumatic fever	M proteins on Group A streptococci Group A streptococcal infection The group A streptococcus bacterium is a form of β-hemolytic Streptococcus bacteria responsible for most cases of streptococcal illness. Other types may also cause infection...  and then myocardial antigen	Macrophage activation Inflammation	Myocarditis Arthritis
Myasthenia gravis Myasthenia gravis Myasthenia gravis is an autoimmune neuromuscular disease leading to fluctuating muscle weakness and fatiguability...	Acetylcholine receptor Acetylcholine receptor An acetylcholine receptor is an integral membrane protein that responds to the binding of acetylcholine, a neurotransmitter.-Classification:...	Competitive acetylcholine inhibition Receptor down-regulation	Muscle weakness Paralysis
Graves disease	TSH receptor	Receptor agonism	Hyperthyroidism Hyperthyroidism Hyperthyroidism is the term for overactive tissue within the thyroid gland causing an overproduction of thyroid hormones . Hyperthyroidism is thus a cause of thyrotoxicosis, the clinical condition of increased thyroid hormones in the blood. Hyperthyroidism and thyrotoxicosis are not synonymous...
Pernicious anemia Pernicious anemia Pernicious anemia is one of many types of the larger family of megaloblastic anemias...  (if autoimmune)	Intrinsic factor Intrinsic factor Intrinsic factor also known as gastric intrinsic factor is a glycoprotein produced by the parietal cells of the stomach. It is necessary for the absorption of vitamin B12 later on in the small intestine...  on gastric parietal cell Parietal cell Parietal cells, or oxyntic cells, are the stomach epithelium cells that secrete gastric acid and intrinsic factor.Acetylcholine and gastrin . The histamine receptors act by increasing intracellular cAMP, whereas the muscarinic and gastrin receptors increase intracellular Ca2+ levels... s	Decreased vitamin B12 Vitamin B12 Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water-soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins...  absorption	Abnormal erythropoiesis Anemia
Unless else specified in boxes, then ref is: * - HDN not taken from

Other examples are:

• Transfusion
  Blood transfusion
  Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...
  
   reactions
• Acute transplant rejection