Your immune system attacks other parts of your body, resulting to redness, pain, swelling or a hot feeling in the lining of a joint, the place where two or more bones come together. This redness, pain, swelling and heat surrounding the joint is called inflammation, which may also affect other internal organs such as the eyes, lungs or heart, and most commonly the hands or feet.

These are the characteristics of rheumatoid arthritis, an autoimmune disorder. In this condition, the bodys immune system attacks healthy joints that cause inflammation in the joint linings. This inflammation can be painful and lead to permanent damage if the condition is not treated.

Joint damage can occur even when pain is not severe. Sometimes it may be too late to remedy the problem by the time X-rays discover its severity. Severe joint damage can lead to permanent joint deformity or disability. In more serious cases, the pain and the swelling may cause difficulty in walking, and in using one's hands for basic movements such as dressing and cooking.

What causes rheumatoid arthritis?
What causes rheumatoid arthritis is still unknown, though much progress has been made in the detection of potential causes. Researchers are still seeking reasons why abnormal responses of the bodys immune system occur; one longstanding theory as to the cause of rheumatoid arthritis can be traced to a combination of factors that causes this disease, including an abnormal autoimmune response, genetic susceptibility, and some environmental or biological trigger, such as viral infection or hormonal changes.

Abnormal Autoimmune Response
The inflammatory process can be traced to the bodys immune system, which fights infection and heals wounds and injuries. When an injury or an infection take place, white blood cells convene to rid the body of any foreign proteins, such as virus. The gathering of blood cells at the injured or infected area produce factors to repair wounds, clot the blood, and fight any infective agents; during this process the surrounding area becomes inflamed and healthy tissues are damaged.

Under normal conditions, the immune system has other factors that control and limit this inflammatory process.

The primary infection-fighting elements are two types of white blood cells called lymphocytes and leukocytes. Lymphocytes have two subtypes known as T-cells and B-cells, both cells designed to recognize foreign invaders (antigens) and to launch an offensive and defensive action against them. B-cells produce separate anti-bodies that can ride along with B-cells or travel on their own to attack the antigen. T-cells have special receptors attached to their surface that recognize specific antigen. This type of cell can be categorized as killer T-cells and helper T-cells. Killer T-cells directly attack antigens that occur in any cells that contain nucleus while helper T-cells possess two roles; they stimulate B-cells and other white cells to attack the antigen and they also produce cytokines, a powerful immune factor that plays an important role in the inflammatory process.

The action of the helper T-cells are of particular importance in what causes rheumatoid arthritis. For some reason, yet to be determined, the T-cells become overactive when rheumatoid arthritis strikes, mistaking the bodys own collagen as an antigen and triggering a series of immune responses to destroy a false enemy. The leukocytes, another major white blood cell in the body, are also prompted into action by the overwhelming T-cells; these leukocytes stimulate the production of key players in the inflammatory process that in excessive amounts become a damaging substance and may play a major destructive role in rheumatoid arthritis.

Genetic Susceptibility
Genetic factors may play some role in what causes rheumatoid arthritis, however studies suggest that it is not necessarily passed on from generation to generation; although the presence of genes that influence the tendency of rheumatoid arthritis may worsen the disease process. It should be pointed out that, while defective genes can be inherited, not all who inherit the gene will develop the disease--it may be mutated by environmental or other factors. This theory needs to be developed through additional research

Environmental Triggers
Infections are credited as an environmental trigger that prompt the onset of rheumatoid arthritis. And although bacteria and viruses have been studied to determine the validity of this claim, no single organism has been identified as the primary trigger for the autoimmune response and successive damaging inflammation.
A number of chemicals are being studied as triggers or causes of rheumatoid arthritis, like silica, which was linked with rheumatoid arthritis in a 2003 study. Other chemicals are still under study; but it remains difficult to determine causal effects of any specific chemical.