Before explaining the science behind ORENCIA, it may be helpful to review some basic
facts about RA.
RA is an autoimmune disease, which means it is a disease of the immune system. The
immune system works to protect the body against attacks by things like bacteria
or viruses. But when it's not working correctly — such as with RA —
the immune system mistakenly attacks the person's own body. With RA, the lining
of the joints, called the synovium (pronounced si-NO-vee-um) is attacked.
Why T cells are believed to be important in RA
One type of cell found within your immune system is called a T cell. When T cells
are activated (or "turned on") they can start a chain of events that is believed
to lead to the inflammation, pain, and joint damage of RA. The activated T cells
begin to multiply and produce special proteins called cytokines (pronounced SIGH-to-kines).
Some important cytokines in the RA process are tumor necrosis factor (TNF), interleukin-1
and interleukin-2. These cytokines are some of the factors that are believed to
drive the inflammation process of RA, often leading to joint damage and destruction.
Controlling the activation of these T cells and the resulting cytokine production
that follows may help reduce inflammation and slow the progression of joint damage.
There are other cell types believed to be related to RA development, such as B cells,
which produce antibodies that may contribute to RA inflammation.

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