Tissue Type Test
A tissue type test is a blood test that identifies
antigens on the surface of body cells and tissues.
Checking the antigens can tell if donor tissue is safe (compatible) for
transplant to another person. This test may also be called HLA typing. Antigens
can tell the difference between normal body tissue or foreign tissue (for
example, tissue from another person's body). Tissue type helps find the best
match for tissues or blood cells (such as
platelets). In some cases, a tissue type test may be
done to see whether a person has a chance for developing certain diseases that
cause the body to attack its own cells, such as
A special pattern of
antigens (called tissue type) is present on each person's cells and tissues.
Half of each person's antigens come from (inherited) the mother and half from
the father. Identical twins have the same pattern, but everyone else has his or
her own special pattern. Brothers and sisters have a 1-in-4 chance of having an
identical match. Each person's antigen pattern can be "fingerprinted" through a
tissue type test.
- The closer the match of antigens, the more
likely that an organ or tissue transplant will be successful.
- The more similar the antigen patterns are from two
people, the more likely it is that they are related.
- Some diseases
multiple sclerosis or
ankylosing spondylitis) are more common in people who
have certain antigen patterns. The reason for this is unknown.
Two main antigen groups are used for a tissue type test.
Class I has three classes of antigens (HLA-A, HLA-B, HLA-C) that are found on
some kinds of blood cells. Class II has one class of antigens (HLA-D) that are
found only on certain cells in the body. There are many different types of
antigens in each category.
Why It Is Done
A tissue type test is done to:
- See if the antigen pattern for donated tissue or
organs (including a blood platelet transfusion or bone marrow transplant) is a
match. The success of a transplant depends on how closely the antigen patterns
match. The antigen patterns are most likely to be similar when the donated
organ or tissue comes from a close relative of the person.
- See how
likely two people are related. If the antigen patterns are very similar, they
are likely to be related. But a tissue type can't prove definitively that two
people are related. A tissue type test may be done as part of a paternity test
to check to see if a man could be the father of a child.
people who may have a high chance of certain autoimmune diseases.
How To Prepare
If you are donating tissue or blood
cells, your doctor may want to talk about your medical history—such as a
history of cancer, infections, high-risk behaviors, use of drugs, exposure to
toxins, and foreign travel. This may be important in understanding whether your
donor tissue can be used.