WASHINGTON. Feb 1: Researchers said on Monday they had found more evidence that bacteria can cause arthritis — In this ease. Salmonella, which causes food poisoning.

They found that" Immune system cells that fight bacteria also sometimes attack norma! cells that happen to carry a protein that resembles a bacterial prolein. reports Reuters.

And other "innocent bystander' cells, which may have been stressed by radiation, environmental toxins or the body's own stress chemicals, can also fall victim, the team at Johns Hopkins University In Baltimore found.

We've found this evidence that the Immune system can be fooled and It suggests subtle changes that could underlie many autoimmune diseases." Mark Soloski, a researcher at Johns Hopkins who led the study, said in a statement.

"As many as 10 per cent of those who get Salmonella develop a reactive kind of arthritis which lasts a few weeks." Soloski said, But a smaller, significant number of those patients gel a severe, debilitating lypc of arthritis that's long-lasting."

People who get Lyme disease, carried by ticks, also can develop arthritis.

Writing tn the journal Nature Medicine. Soloski's team said they looked at the effects of Salmonella Infection In mice.

They watched Immune cells known as cytotoxic T lympho- t vies (CTLs) as they approached Infecled cells, which attract the CTLs by displaying "flags" or pieces of protein from the bacteria.

Mouse cells infected with Salmonella used a "flag" almost Identical to parts of a "universal housekeeping molecule" known as a heat shock protein and found In all living organisms.

The rcsearchters artificially caused mouse cells to display ihe Salmonella "flag." and the mouse CTLs. as they should, attacked them. But CTLs also attacked If the cells displayed a piece of the mouse's own housekeeping molecule or the Identical human version.