Immunology for Everyone What causes psoriasis

A key component in the immune system is a group of cells called white blood cells, which help defend the body against foreign invaders and microorganisms. One type of white blood cell that is believed to be of crucial importance in causing psoriasis is the T lymphocyte. What causes psoriasis

The T lymphocytes are very "smart" cells because they have terrific memories. In fact, once they are exposed to a foreign substance, they remember it forever. With subsequent exposures, the T lymphocytes will recognize the substance and multiply to attack it. Hence, they are known as memory T cells.

While T cells have great memories for foreign substances, they need a teacher. That teacher is known as an Antigen Presenting Cell (APC), which does exactly what its name says: it presents antigen (foreign substances) to the T cell and "teaches" the T cell about the antigen. The T cell, with its fantastic memory, will then remember that foreign substance in future encounters.

In psoriasis, activated T cells accumulate in the outer layer (epidermis) and inner layer (dermis) of the skin, where they reproduce at a rapid rate due to chemicals called cytokines, such as TNF-alpha, which sends a faulty message to the skin, causing the skin cells to grow and divide more rapidly and resulting in the thick, scaly skin of psoriasis. The reason this happens and the exact process continue to be the focus of intense scientific research. What causes psoriasis

Researchers in the mid-1990s proved that T cells in the skin release specific cytokines (proteins) that are capable of causing skin cells to grow. Researchers are still carefully examining the process to determine the specific antigen that activates the immune system and fuels the entire process—the so-called "key" to psoriasis.

Taken together, this summarizes our current understanding of the immune mechanisms causing psoriasis. This has taken scientists more than 20 years to understand. These understandings have provided important insight into permitting the development of new medicines to treat these immune defects and improve psoriasis.

Who Is Most at Risk? What causes psoriasis

Psoriasis is most commonly diagnosed between the ages of 15 and 35, but it can occur at birth or, less often, in the elderly. The average age of onset in males is 29, and in females, 27. A second peak can occur in the mid-50s. About 10 to 15 percent of all cases occur in children under the age of 10. Men and women are affected equally. Although anyone can develop psoriasis, the incidences are much lower in West Africans, African Americans, Japanese, Inuit and Native Americans, a fact that led researchers to believe the cause of psoriasis might involve genetic and environmental factors or triggers. What causes psoriasis

Click to continue
Top of page What Causes Psoriasis 2