In medicine

Medicine

Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

, photopheresis or extracorporeal photopheresis is a form of apheresis

Apheresis

Apheresis is a medical technology in which the blood of a donor or patient is passed through an apparatus that separates out one particular constituent and returns the remainder to the circulation...

 and photodynamic therapy

Photodynamic therapy

Photodynamic therapy is used clinically to treat a wide range of medical conditions, including malignant cancers, and is recognised as a treatment strategy which is both minimally invasive and minimally toxic...

 in which blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 is treated with photoactivable drugs which are then activated with ultraviolet light.

Photopheresis is currently standard therapy approved by the U.S. Food and Drug Administration (FDA) for cutaneous T-cell lymphoma

T-cell lymphoma

The T-cell lymphomas are the four types of lymphoma that affect T cells. These account for perhaps one in ten cases of non-Hodgkin lymphoma.They can be associated with Epstein Barr virus and Human T-cell leukemia virus-1.-Types:The four classes are:...

. In this procedure, buffy coat

Buffy coat

The buffy coat is the fraction of an anticoagulated blood sample after density gradient centrifugation that contains most of the white blood cells and platelets.-Description:...

 (WBC

White blood cell

White blood cells, or leukocytes , are cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a...

 + platelet

Platelet

Platelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes.  The average lifespan of a platelet is normally just 5 to 9 days...

s) is separated from whole blood, chemically treated with 8-methoxypsoralen (instilled into collection bag or given per os in advance), exposed to ultraviolet light, and returned to the patient.

8-Methoxypsoralen irreversibly binds covalently to both strands of the DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 of nucleated cells following photoactivation. The photochemically damaged T-cells returned to the patient appear to induce cytotoxic effects on T-cell formation. The mechanism of such “antitumor” action has not been elucidated.

Minimal observed side effect

Adverse effect

In medicine, an adverse effect is a harmful and undesired effect resulting from a medication or other intervention such as surgery.An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. If it results from an unsuitable or incorrect dosage or...

s for patients receiving photopheresis include hypotension

Hypotension

In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...

 and syncope

Syncope (medicine)

Syncope , the medical term for fainting, is precisely defined as a transient loss of consciousness and postural tone characterized by rapid onset, short duration, and spontaneous recovery due to global cerebral hypoperfusion that most often results from hypotension.Many forms of syncope are...

 resulting from volume shifts during leukapheresis

Leukapheresis

Leukapheresis is a laboratory procedure in which white blood cells are separated from a sample of blood. It is a specific type of apheresis, the more general term for separating out one particular constituent of blood and returning the remainder to the circulation.Leukapheresis may be performed to...

 phase of treatment. Photopheresis is also used as an experimental treatment in patients with cardiac, pulmonary and renal allograft rejection, graft-versus-host disease

Graft-versus-host disease

Graft-versus-host disease is a common complication after a stem cell transplant or bone marrow transplant from another person . Immune cells in the donated marrow or stem cells recognize the recipient as "foreign". The transplanted immune cells then attack the host's body cells...

, autoimmune diseases, nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis or nephrogenic fibrosing dermopathy is a rare and serious syndrome that involves fibrosis of skin, joints, eyes, and internal organs. Its cause is not fully understood...

 and ulcerative colitis

Colitis

In medicine, colitis refers to an inflammation of the colon and is often used to describe an inflammation of the large intestine .Colitides may be acute and self-limited or chronic, i.e...

.

External links

• American Society for Apheresis
• Extracorporeal photopheresis entry in the public domain NCI Dictionary of Cancer Terms
• Extracorporeal photopheresis definition at eMedicine.com
• Extracorporeal photopheresis discussion at Stanford School of Medicine