June 14, 2003
Ivanhoe Broadcast News
Multiple sclerosis affects 350,000 Americans and is, with the exception of trauma, the most frequent cause of neurological disability beginning in early to middle adulthood.
Multiple Sclerosis is an autoimmune disease that affects the central nervous system. The CNS consists of the brain, spinal cord and the optic nerves.
Surrounding and protecting the nerve fibers of the CNS is a fatty tissue called myelin, which helps nerve fibers conduct electrical impulses. In patients with multiple sclerosis, myelin is lost in multiple areas, leaving scar tissue called sclerosis.
These damaged areas are also known as plaques or lesions. Sometimes the nerve fiber itself is damaged or broken. When myelin or the nerve fiber is destroyed or damaged, the ability of the nerves to conduct electrical impulses to and from the brain is disrupted, and this produces the various symptoms of MS.
Symptoms include bladder dysfunction, dizziness, cognitive dysfunction, fatigue, tremors and vision problems.
Doctors now have a new option for helping people with MS – an experimental drug called CAMPATH-1H. It works by destroying the body's T cells, which are believed to be responsible for initiating the destructive process seen in multiple sclerosis. In one small trial of 27 people with secondary progressive MS, the drug was found to virtually eliminate the formation of new lesions and the inflammation associated with the disease for at least 18 months.
For 14 of the study participants, the progress of their disease was completely halted. In the remaining 13, MS symptoms continued to worsen even in the absence of new lesions.
CAMPATH-1H is called an anti-CD52 monoclonal antibody. Antibodies are small proteins produced by the immune system that stick to small sections of other proteins known as epitopes.
Proteins containing such epitopes are called antigens. Once attached to an antigen, the immune system can destroy the cell to which the anitbody belongs.
Antibodies are extremely specific to particular antigens and will usually only stick to a single one. The immune system usually targets antigens belonging to viruses, bacteria and other unwelcome invaders but it can also attack the body's own cells as it does in the case of autoimmune diseases.
Because antibodies are so specific, researchers have looked at ways to engineer antibodies that can disable targeted cells in the human body. These are known as monoclonal antibodies and have been called "magic bullets.”
CAMPATH-1H is one of these. It is designed to latch onto cells that
express a protein called CD52 thereby killing them. CD52 is expressed on
the surface of several types of white blood cells including lymphocytes
(T-cells). CAMPATH-1H has been shown to be very effective at destroying
T-cells, the cells responsible for initiating the damage in multiple sclerosis.
CAMPATH-1H is FDA-approved for the treatment of chronic myelogenous leukemia.
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