Cytokines and the Inflammatory Response. The inflammatory response is the product of an overactive immune system and is a major destructive force in an autoimmune disease.
- Once the lymphocytes have launched a response to an antigen, they also release masses of other white blood cells to gather at the injured or infected site.
- The major players in this response are white blood cells called leukocytes. Researchers are particularly interested in leukocytes called cytokines. These are small powerful proteins that, in tiny amounts, are indispensable for healing. When they are overproduced, however, which occurs in MS, they play a major role in the destructive process.
- Their intensive convergence on the affected area causes it to be become inflamed and injurious to the very cells they are designed to protect. Under normal conditions, this inflammatory process is controlled and self-limiting, but in people with autoimmune diseases such as multiple sclerosis, the process persists and damage occurs in the surrounding tissues.
Important cytokines in MS appear to be tumor necrosis factors, interleukin-12, and interferon-gamma. Other cytokines, including interleukin-10 and transforming growth factor beta, may play a protective role and help block inflammatory activity.
Axon Destruction and Progression of MS
The inflammatory response may trigger the disease, but afterward a progressive course takes over that does not appear to be related to inflammation. Experts have found that destruction of axons, the long filaments that carry electric impulses away from a nerve cell, is a major feature of multiple sclerosis. In fact, it may be the major cause of permanent disability that occurs with this disease. Microscopic studies reveal that axons are injured early on as "bystanders" while myelin is being peeled off. As the disease progresses, these weakened and exposed axons degenerate further. Most of the damage occurs early in the disease process and decreases over time, although some destruction can still be observed years and decades afterward. Such evidence is having significant effect on approaches to treatment and research.
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