What is the Human Leukocyte Antigen?

Human leukocyte antigens (HLA) relate to a number of genes that regulate the immune system. Proteins encoded in gene cells are known as antigens, which play a critical role in organ transplants and the compatibility of donors and recipients. Antigens act as defenses against disease, and could affect autoimmune diseases. The HLA system might also determine a person's particular smell and influence the selection of a mate for reproduction.

This system represents the major histocompatibility complex in human beings, which means they have the same or most of the same sets of genes. Genes found on chromosome 6 make up the human leukocyte system, which encodes cell molecules that provide immune benefits to T-cells in the body. Finding two unrelated people with the same HLA molecules at this location is extremely rare.

The human leukocyte antigen system was discovered by researchers looking for ways to transplant organs from one individual to another. They found that the immune system’s white blood cells create antibodies to fight exposure to infection. When a foreign antigen is introduced through organ transplants, the body's immune system attacks the donor tissue if it is not compatible with genes of both the donor and the recipient of the organ or tissue. Surgeons conduct human leukocyte antigen testing to find similar HLA to lessen the chance of rejection of the organ.

Human leukocyte antigen testing matches samples from potential donors with antigens found in the recipient. This evaluation, along with blood typing, is done for transplants including the kidney, bone marrow, and liver. The higher the number of identical HLA antigens in both people, the greater the chance that the transplant will be successful.

Antigen testing is also performed during paternity tests. HLA antigens of the named father, the mother, and the child are compared for similarities after a blood sample from all three is obtained. If a child produces antigens that are not present in the adults, the supposed father can be excluded as a parent.

HLA types are inherited in six spots on chromosome 6, with some of them connected to autoimmune disorders and other conditions. A person who inherits specific antigens from his or her parents is more prone to develop diseases including diabetes and lupus. Cancer and heredity diseases are also linked through human leukocyte antigen systems, meaning doctors can now target abnormal cells before they develop into a cancerous state.