Arthritis Arthritis Basics

Rheumatoid Arthritis: Immunological Factors

Rheumatoid arthritis is an autoimmune disease which occurs when the immune system creates an unwanted response that targets the body’s tissues and organs.

Normally, a healthy immune system counts on tiny white blood cells that circulate throughout the body to protect it from viruses, bacteria, cancer cells, toxins and other foreign invaders. The presence of the foreign substances, or antigens, activates the white blood cells to mount an immune response that entails recognizing and destroying the invaders that can cause the body harm.

Differentiating Between T cells and B cells
Trillions of white blood cells carry out this important task. The two major classes are called T cells and B cells.

T cells work in two ways. They attack, surround and essentially disarm the invaders. They also direct and regulate the body’s immune response.

In autoimmune diseases, something triggers the body to mount an abnormal immune response, including the stimulation of T cells and the production of antibodies. As a result, the immune system begins attacking the very cells, organs and tissues in the body that it is supposed to protect. In the case of rheumatoid arthritis, the cells set off a reaction that causes inflammation to occur in the lining of the joints, also known as the synovium.

The B cells work primarily by releasing specific antibodies into the body’s fluids. The antibodies then ambush the antigens and pave the way for T cells to do their job.

One of the antibodies produced by B cells is called rheumatoid factor. Research indicates that people with high levels of rheumatoid factor may have a malfunctioning immune system. That explains why doctors often request a test that measures the level of rheumatoid factor when trying to diagnose rheumatoid arthritis. In general, the higher the level of rheumatoid factor present in the body, the more severe the disease activity is likely to be.

However, not all people with rheumatoid arthritis have an elevated rheumatoid factor, and not all people with an elevated rheumatoid factor have rheumatoid arthritis. The test can also come out negative if it is done too early in the course of the disease. Approximately 20 percent of people with rheumatoid arthritis will have a negative rheumatoid factor test and some people who do not have rheumatoid arthritis will test positive.

The Role of Cytokines
Another essential part of the immune response takes place when white cells secrete substances or proteins known as cytokines. These proteins serve many roles. They encourage cell growth and spark cells to activate. They also communicate messages to cells.

In the over-stimulated immune system, cytokines tell cells to reproduce and mature at a much faster rate. In effect, the cytokines are causing the activation of additional T cells, which releases more cytokines, perpetuating the cycle of damaging inflammation.

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