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Thymus Transplants Give Hope to Babies with Fatal Immune Disease

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Duke Health News 919-660-1306

DURHAM, N.C. -- "My baby is doing what other babies her age
are doing -- she's feeding herself, putting on her own clothes
and she loves to dance."

Lolita Harding is describing her daughter Dave'yana, who
will turn three in September, thanks in large part to a thymus
transplant she received at Duke University Medical Center in
April 2005 to reconstitute her absent immune system. Dave'yana
was the 31st baby to receive such a transplant at Duke to
correct immune system deficiencies caused by a condition called
DiGeorge anomaly. Duke is the only center in the world that
performs the procedure.

The latest results of Duke's experience with this treatment
of DiGeorge anomaly, published Tuesday, May 15, in the journal
Blood, show that 75 percent of the babies who received a thymus
transplant were alive after one year. The recipient of the
first transplant, in 1994, is alive and well.

The current study was supported by the National Institutes
of Health and the Food and Drug Administration.

DiGeorge anomaly is marked by the lack of a functioning
thymus, a gland that is responsible for "teaching" immune
system cells known as T cells how to attack and fight off
infections. Babies with DiGeorge anomaly also can have a range
of problems including heart defects and unusual facial
features. However, about 1 percent of these babies have no
thymus at all, a situation that ends in death, usually by
infection. These are the patients who are candidates for thymus
transplantation.

"We want people to know that when the diagnosis of complete
DiGeorge anomaly is made, it is no longer a death sentence,"
said pediatric immunologist Louise Markert, M.D., Ph.D., who
developed the procedure. "There is a treatment available --
thymus transplantation -- that has led to survival of most of
the infants who otherwise would have died."

For the procedure, surgeons obtain thymus tissue that
usually is discarded from babies undergoing heart surgery.
Since the gland is large and covers the heart in infants,
surgeons must remove all or part of it to gain access to the
heart. The removed thymus tissue is grown in culture for
several weeks in a laboratory while researchers ensure that
there are no diseases present in the tissue. Strips of tissue
are then implanted in the baby's thigh, where they attract a
blood supply and begin to act like a thymus gland. Within three
to four months, mature T cells begin to appear in the
bloodstream.

The latest Duke analysis followed the first 54 children with
DiGeorge anomaly referred to Duke for possible thymus
transplantation. Of those, 44 received the procedure. So far,
32 of the children who received the transplant are alive, with
a follow up of as long as 13 years.

Markert said the 12 deaths occurred within one year of the
transplant. The deaths were caused by various infections and
were not a result of the surgery itself, she said.

"These babies are very frail when they get here, so it is
crucial that they are nourished and supported during this
period after transplant to strengthen and maintain them as
their immune systems rebuild," Markert said. "We have a
remarkable team that takes care of these children in tightly
controlled conditions during this important early period."

Typically, children remain in the hospital for two to three
months after transplantation as physicians work to keep
infections at bay as the child's immune system develops. In
Dave'yana's case, Harding returned to the hospital in Missouri
after about a month. She received treatment for a viral
infection at the Children's Hospital of St. Louis for four
months after which her immune system was strong enough to get
rid of the virus and prevent other infections. Dave'yana then
went home.

"If it wasn't for Dr. Markert and her team, my baby would
not be here right now," Harding said. "They really fought for
my baby to get the transplant."

Whether she likes it or not, later this month Dave'yana,
because of her new immune system, gets to experience what other
children her age face -- standard childhood immunization
shots.

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