Wednesday, January 21, 2009

New hope for organ recipients

Wouldn't it be wonderful if organ recipients did not have to worry about their immune systems rejecting their new organs? Maybe some day in the future a treatment will be developed to prevent rejection and this article offers hope for one potential solution.

By Danny Rose, Medical Writer

Australian scientists have stumbled across a "weird" effect within the immune system that offers hope of a new treatment to help transplant recipients accept their donor organs.

Researchers at Sydney's Garvan Institute set out to investigate how inflammation works in transplants with an experiment using the immune system's most powerful "activator" - a hormone called B cell activating factor or BAFF.

Mice were genetically engineered to produce large amounts of BAFF, in the expectation studies would show how their boosted immune systems would rapidly reject any foreign tissue.

But the exact opposite happened, as the mice accepted their tissue transplants without the need for conventional treatment to suppress the immune system.

"I went to my boss and said `Hey, look at this. This is really weird'," Garvan Institute masters student Stacey Walters said of the moment she made the discovery.

Dr Shane Grey, of the institute's Immunology and Inflammation Program, said he and fellow scientists were "floored".

"Trolling through the scientific literature would make you think `Wow, this BAFF molecule is a very powerful activator of the immune system'," he said.

"To come out with a finding to say that having more of it prevents inflammation, and stops T cells from destroying tissues, at the outset it seems so surprising."

T cells are white blood cells that play a direct role in killing off foreign tissue, and Dr Grey said it seemed the extra BAFF - which led to a higher number of regulating B cells in the blood - had increased T cell tolerance.

The surprise discovery could lead to a targeted treatment for organ transplant recipients, as conventional methods suppress the whole immune system and place already sick people at risk of further illness.

"What we'd like to be able to do is say here's your organ graft and here's some therapies that actually modulate the immune system that is attacking (it)," Dr Grey said.

"But everything else is still working fine - you still have a viral response, you're still making antibodies, you can still clear other infections.

"This provides a lot of hope to say these strategies will happen."

The findings are published in the Journal of Immunology.

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