Rheumatoid Arthritis is a multifactor disease involving multiple joints giving rise to pain, swelling in and around the affected joint, redness and increase in the local temperature.

The exact cause of rheumatoid arthritis is not known. Earlier, it was suspected that some infective agents like bacteria, virus and fungi have a predisposing role towards occurrence of rheumatoid arthritis in some genetically susceptible host, but it was not proved as the exclusive cause.

Infective hypothesis- Due to the global distribution of the disease, an assumption was made that infection may have a significant role, but the precise causative organism must be omnipresent. A number of probable causative agents are under supervision.

These are Epstein - Barr virus (EBV), Mycoplasma, Rubella virus, Cytomegalovirus and Parvovirus. Still no conclusive proof has been established. The hypothesis of an infective agent causing chronic severe inflammatory reaction around joint also remains under controversy.

The one probable cause may be the persistent infection of the articular cartilage and its surrounding structures or retention of the remnants of the infectious agent inside the synovial tissue that produces the chronic inflammatory reaction.

Few scientists have found out that the patients having rheumatoid arthritis had suffered from the infection with Proteus mirabilis at some part of their lifetime.

Genetic factors- Another hypothesis of rheumatoid arthritis is that it is genetic in origin. It was found that monozygotic twins have four fold increased chance of getting the active process of the disease than the dizygotic twins who possess similar chance developing the disease.

It was also noted that the first degree relatives of the patients suffering from severe rheumatoid arthritis have a four times increased risk of acquiring the disease, which is having the autoantibody- the Rheumatic factor. Highest risk of association of the disease is seen among the twins who possess two HLA-DRB 1 alleles known to be related with rheumatoid arthritis.

Class-II major histocompatibility complex gene HLA-DR 4 (DR²1*0401) and associated alleles are known to be key genetic risk factors for developing rheumatoid arthritis. Researchers have shown that almost 70% of the patients who are suffering from classic form of rheumatoid arthritis states HLA-DR 4 in comparison to 28% of control group. Association of HLA- DR 4 is seen in many ethnic groups.

This includes North American and European white population, Indian native population and the Japanese. Some people in Israel, Asian Indians and the Yakima Indians of North America have shown association with HLA- DR 1 (DR²1*0101) and HLA- Dw 16 (DR²1*1402).

Environmental factor- Genetic factors or the infective hypothesis do not fully conform the occurrence of rheumatoid arthritis. So, it is assumed that some environmental factors may play a role for the etiology of the disease.

Epidemiologic studies conducted in the Africa threw some light to the deleterious role of the urbanization and changes in the climate. It was also reported that tobacco smoking increases the incidence of rheumatoid arthritis.

In spite of determining the exact triggering agent, it is definite that the result in the immune system that is equipped with the power to start the inflammatory process in the joints and occasionally different tissues of our body. Immune cells (T & B lymphocytes) are stimulated.

The chemical messengers (cytokines. TNF ±/ Interleukin-1) are expressed in the joints and the surrounding tissues.