What is CD55 and CD59?

The regulatory proteins CD55 and CD59 are glycolsylphosphatidylinositol-anchored, type I cell surface proteins, which inhibit formation of the C3 convertases and prevent the terminal polymerization of the membrane attack complexes, respectively.

What is the role of CD59?

Function. CD59 inhibits the formation of MAC pores in the membranes of expressing cells: it is a ‘suicide inhibitor’, locking onto C8 in the forming MAC to block the recruitment of C9 into the complex. In common with other GPI-linked proteins, cross-linking of CD59 can cause cell activation.

What causes the hemolysis in paroxysmal nocturnal hemoglobinuria?

PNH, or Paroxysmal nocturnal hemoglobinuria, is a rare blood disease that causes red blood cells to break apart. Doctors call this breaking apart “hemolysis.” It happens because the surface of a person’s blood cells are missing a protein that protects them from the body’s immune system.

What are the symptoms of PNH?

Overall, the most common symptoms of PNH include:

• Significant fatigue or weakness.
• Bruising or bleeding easily.
• Shortness of breath.
• Recurring infections and/or flu-like symptoms.
• Difficulty in controlling bleeding, even from very minor wounds.

Is PNH an autoimmune disease?

Paroxysmal cold hemoglobinuria is a rare autoimmune hemolytic disorder characterized by the premature destruction of healthy red blood cells (hemolysis) minutes to hours after exposure to cold.

Is PNH inherited?

This condition is acquired, rather than inherited. It results from new mutations in the PIGA gene, and generally occurs in people with no previous history of the disorder in their family. The condition is not passed down to children of affected individuals.

What is CD59 deficiency?

Abstract. CD59 deficiency is a common finding in RBCs and WBCs in patients with chronic hemolysis suffering from paroxysmal nocturnal hemoglobinuria in which the acquired mutation in the PIGA gene leads to membrane loss of glycosylphosphatidylinositol-anchored membrane proteins, including CD59.

What does CD63 stand for?

Cell Surface Antigen
CD63 (Cell Surface Antigen) CD63 is a member of the tetraspanin superfamily of activation-linked cell surface antigens that is known for its abnormally high levels on the surface of activated basophils (334), on proliferating mast cells (335,336), and on the surface of endothelial cells in inflamed tissue (336).

Why is PNH negative?

Paroxysmal nocturnal hemoglobinuria (PNH) DAT results are negative, as are results from the D-L antibody test. Testing for paroxysmal nocturnal hemoglobinuria depends on the absence of the GPI antigens determined via various tests, including the highly sensitive flow cytometry and the bacterial toxin aerolysin assay.

Can PNH go away?

Most patients who have had PNH for a long period of time have relatively stable clone sizes although in some the clone can gradually reduce in size. In a small proportion of patients (less than 20% of patients in our experience) the clone can disappear altogether although this generally occurs over several years.

What is DAF in immunology?

Decay-accelerating factor (DAF) is a membrane protein that inhibits activation of the C3 complement component and thereby protects RBCs from complement-mediated pore formation and eventual cell lysis (Brodbeck, Mold, Atkinson, & Medof, 2000; Michaels, Abramovitz, Hammer, & Mayer, 1976).

What are exosome markers?

Exosomes are small vesicles composed of a lipid bilayer. Exosomes are formed when certain endosomes, called multivesicular bodies, fuse with the plasma membrane, releasing them into the extracellular environment. They may also be directly released from the plasma membrane.

How does CD59 attach to the host cell?

CD59 attaches to host cells via a glycophosphatidylinositol (GPI) anchor. When complement activation leads to deposition of C5b678 on host cells, CD59 can prevent C9 from polymerizing and forming the complement membrane attack complex. It may also signal the cell to perform active measures such as endocytosis of the CD59-CD9 complex.

Which is an alternative ligand for CD2 or CD59?

CD59 has been described as an alternative ligand for CD2 and implicated in T cell activation. 10,11 CD59 has been ‘pirated’ for use as an essential receptor for the streptococcal cytolytic toxin, intermedilysin. 12

What kind of protein is the CD59 gene?

CD59 glycoprotein, also known as MAC-inhibitory protein (MAC-IP), membrane inhibitor of reactive lysis (MIRL), or protectin, is a protein that in humans is encoded by the CD59 gene. It belongs to the LY6/uPAR/alpha-neurotoxin protein family.

How are CD59 levels affected by inflammatory arthritis?

CD59 expression by cells is upregulated in response to a number of stimulants including cytokines, phorbol myris-tate acetate, and calcium ionophore (102, 388, 389, 390 ). Levels of CD59, together with MCP and DAF, are increased in joints affected by inflammatory arthritis, possibly in response to attack by activated complement components ( 391 ).