Additional factor ID'd in rheumatoid arthritis

[Guest guest]

Additional factor ID'd in rheumatoid arthritis

Last Updated: 2002-09-05 16:30:31 -0400 (Reuters Health)

By Alison McCook

NEW YORK (Reuters Health) - Researchers have uncovered a type of cell that

may play a key role in the development of inflammatory types of arthritis in

mice.

The newly discovered factor is mast cells, which are also found in humans,

where they tend to be involved in allergies. Mast cells are also present in

the inflamed joint tissue of people who suffer from forms of inflammatory

arthritis--most commonly, rheumatoid arthritis.

Lead author Dr. M. Lee of Harvard Medical School and Brigham and

Women's Hospital in Boston, Massachusetts, told Reuters Health that because

these results are from mice, they cannot be directly applied to humans. And

the findings provide only a preliminary understanding of the importance of

mast cells, he added. Although the results suggest that mast cells are

involved in this form of arthritis, just what role those cells play in the

disease remains unclear.

Lee said he hopes these findings encourage other investigators to look more

closely at mast cells, and suggested that the cells may, in the future, be

used as part of new therapies to treat inflammatory arthritis. " It's our

hope that this (study) will spur more investigations into the role of these

cells in human disease, " Lee said.

Rheumatoid arthritis is a chronic disease in which the body's own immune

system attacks the tissue lining the joints. It is more common in women,

tends to strike between the ages of 36 and 50, and results in chronic

destruction and deformity of the joints.

Lee and his team obtained their findings using mice that had certain genetic

changes that left them essentially without mast cells. The researchers then

injected the mice with fluid extracted from other mice with arthritis, a

procedure that would normally cause new cases of arthritis in the injected

mice. However, the mice without mast cells remained arthritis-free.

To further test the importance of mast cells in arthritis, the researchers

injected mast cells into mice that had none, all of whom then developed

arthritis after being given the fluid as easily as mice with normal mast

cell levels, according to the report in the September 6th issue of Science.

Based on these findings, Lee told Reuters Health in an interview that he and

his colleagues suspect mast cells play a role in the development of

rheumatoid arthritis.

Lee explained that arthritis may involve the activity of proteins in the

body called autoantibodies, which, in some people, cause problems by

attacking the body's own tissues as if they were dangerous, foreign

substances. Although the role autoantibodies play in inflammatory arthritis

is not yet clear, Lee suggested that mast cells may act as a link in the

chain between autoantibodies and the substances they act upon, thus enabling

the antibodies to produce their effects.

Although treatments using mast cells are likely years away, Lee said that if

researchers continue to investigate the cells, and if they are also found to

be important in humans with rheumatoid arthritis, this research could

eventually produce new, more effective means to help people with the

condition. " That's a very exciting potential, or possibility, " he said.

SOURCE: Science 2002;297:1689-1692.