How can someone have HLA Antibodies against other people that can cause incompatibility?

A recipient’s level of sensitization is an important factor in transplant compatibility. People become “sensitized” when their immune system develops antibodies after being exposed to someone else’s tissue. This exposure can occur through:

• Pregnancy

• Blood transfusions

• Previous organ transplants

The more antibodies a person has, the more difficult it becomes to find a donor whose HLA types will not trigger an immune reaction. For this reason, avoiding unnecessary blood transfusions is extremely important. Additionally, each new transplant increases the risk of immunologic rejection, which is why the kidney to be transplanted must be carefully evaluated beforehand.