Organ Transplantation - Biotechnology and Your Health: Pharmaceutical Applications - page 123

must come from people who signed a donor card before they died
or whose family agrees to the organ donation. The gift of an organ
at the sad time of the sudden loss of a family member in an accident
is an act of great generosity. Despite these gifts, every year a short-
age of healthy organs causes many more sad results—the death of
people on the waiting list. In 2003, more than 6,000 people died
while waiting for an organ.
Human-to-human organ transplantation has risks. The human
immune system is finely tuned to recognize and destroy invaders,
and because it carries different forms of transplantation markers
from those of the recipient, the transplanted organ is seen as an
invader, unless the donor and recipient share exactly the same genes,
as in that first successful kidney transplant between identical twins.
A major risk exists if antibodies to the donor cells are present in the
recipient's blood at the time of transplant. If donor-reactive anti-
bodies are present when the blood connection to the organ is made
during surgery, the reaction against the new organ may be so rapid
that the blood vessels are blocked and the organ cells die. This rapid
antibody reaction to the cells lining the organ blood vessels is called
hyperacute rejection . Tests for antibodies lurking in the recipient's
blood that could cause hyperacute rejection are performed before
the transplant to determine who receives a donated organ. The ABO
blood group system, critical in blood transfusion, is also important
for some, but not all, transplanted organs. An organ donor must
be a suitable ABO type for the patient or ABO antibodies in the
recipient's blood will cause hyperacute rejection.
After the surgery, new antibodies and killer lymphocytes that
cause rejection may develop within days. To prevent this from hap-
pening, or at least reduce the chances of it, scientists have discovered
and developed a number of immunosuppressive drugs that help extend
the life of the transplanted organ and, thus, the life of its recipient.
Corticosteroids and the cancer chemotherapy drug azathioprine
were the first drugs used to suppress the immune system for organ