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Thought this would be of interest!

Martha Murdock, Director

National Silicone Implant Foundation

Dallas, Texas Headquarters

----- Original Message -----

From: " Robin Amerine " <Robin.Amerine@...>

<UTSWNEWS@...>

Sent: Thursday, March 01, 2001 9:31 AM

Subject: News release from UT Southwestern March 1, 2001

Media Contact: on

214-648-3404

susan.morrison@...

RESEARCHERS DISCOVER THYMUS GLAND PLAYS ROLE IN FIGHTING INFECTION AFTER

BONE-MARROW TRANSPLANTATION

DALLAS - March 1, 2001 - The thymus gland, until recently thought to be

inactive after childhood, plays an important role in immune system

reconstitution after bone-marrow transplantation, researchers at UT

Southwestern Medical Center at Dallas have discovered.

In a paper published in today's issue of Blood, the journal of the American

Hematological Society, the researchers report that the thymus continues to

function in adulthood and can affect a patient's recovery from allogeneic

stem-cell transplantation. In allogeneic transplants, the patient receives a

donation of stem cells or bone marrow from a donor, usually a close

relative. Many of those patients develop graft-vs.-host disease, in which

the new donor-derived immune system recognizes the recipient's body as

foreign.

The thymus gland produces T-cells, which fight infection and thus help

patients recover from a transplant.

" T-cells are one of the most important parts of the immune system. They are

white blood cells that are responsible for 'coordinating' the body's immune

response against viruses, parasites and bacteria. They are essential, " said

Dr. Douek, assistant professor of internal medicine at UT

Southwestern.

Although previous studies showed the thymus was only active in childhood and

then atrophied, in 1998 these UT Southwestern researchers reported in Nature

that the thymus gland continues to produce T-cells throughout life. Their

study involved patients with damaged immune systems due to HIV.

In the Blood paper, the researchers looked at the role of the thymus gland

in immune reconstitution after bone-marrow or stem-cell transplants in

people who have been treated for leukemia. Chemotherapy depletes T-cells in

these patients.

" It's important because if you want to end up with a normal immune system -

like the immune system of a healthy child - you need your thymus, " said

Douek. " The young

immune system has a broad repertoire; it can recognize a wide range of

viruses. The older you get, the more skewed the repertoire gets due to

exposure to more and more diseases. If you get exposed to a flu virus, for

example, many T-cells will respond to that flu virus and proliferate, and

your immune system will be weighted toward that flu virus. "

In a study published last year in The Lancet, UT Southwestern researchers

studied patients who had received autologous bone-marrow transplants,

meaning they received their own bone marrow after chemotherapy. They found

that in these patients, ranging in age from 34 to 66, their thymuses

reconstituted their immune systems.

The most recent study involved patients who received the more common

allogeneic transplants. " What we asked in this study was: Does the thymus

help make a new immune system after allogeneic bone-marrow transplants? We

found that the answer was yes, it does; it contributes an enormous amount,

especially in children, " Douek said. The researchers then looked at the

major factors affecting thymic output " so that if there are things that

inhibit thymic output, we can try to clinically prevent that from

occurring. "

" We found that with increasing age, thymic output decreased, which is what

we would have expected. Most importantly, we found that graft-vs.-host

disease completely shuts off output of new cells from the thymus, " he said.

" We know thymic output is beneficial; we know that it occurs; and we know

the most damaging thing to thymic output is graft-vs.-host disease. You have

to try to fight GVHD if you're going to reconstitute a new immune system

with a broad repertoire. "

GVHD is treated with immunosuppressive drugs, and the researchers found that

those drugs do not inhibit thymic output, he added. This means GVHD could be

treated early and aggressively without impairing thymic output. Douek said

the next step is to study the pathways of immune reconstitution to aid in

the development of various compounds for use in clinical trials.

" This sets the groundwork for clinical trials to improve immune

reconstitution, " Douek said.

The study included 67 patients, from infants to adults, at four medical

centers: UT Southwestern, Children's Hospital of Los Angeles,

Fairview-University Medical Center in Minneapolis and Baylor University

Medical Center in Dallas.

Participating researchers from UT Southwestern were Brenna J. Hill, research

assistant in internal medicine; Dr. A. Koup, chief of infectious

diseases; Dr. R. Betts, fellow in internal medicine; and Dr.

H. , associate professor of internal medicine and director of UT

Southwestern's bone-marrow transplant program. Other researchers involved

were Drs. Weinberg and Monika Smogorzewska of Children's Hospital of

Los Angeles, Drs. Bruce R. Blazar and E. Wagner of the University of

Minnesota School of Medicine, and Dr. Agura of Baylor University

Medical Center.

The research was funded in part by the Leukemia and Lymphoma Society of

America.

###

This news release is available on our World Wide Web home page at

http://www.utsouthwestern.edu/home_pages/news/

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