Procedure for HLA determination

HLA can be determined in four different ways. In each case, tissue from both donor and recipient is required. The exact determination of the structure of the HLA is done with the so-called antigen determination.

The process of the polymerase chain reaction (PCR) is used for this. In this process cells are destroyed and the exact sequence of bases of the DNA, which is released by the destruction, is reproduced and multiplied with the help of an enzyme. It is also possible to test whether the immune system of the recipient of a donation has ever had to react to exogenous HLA.

For this purpose, immune cells of the donor are added to the blood of the recipient. In the absence of a reaction, there was no contact yet. This test is called antibody detection.

Finally, the tolerability of an organ donation can be assessed by the so-called crossmatch test. The test is similar to antibody detection. Recently, the so-called flow cytometry can also provide automated results. In order to be able to reproduce antibody detection, it is advisable to first obtain information about antibodies and their significance. We offer the following articles for this purpose: What are antibodies?

HLA Subgroups

The HLA-B27 antigen belongs to the second group of HLA. It is found on almost all cells of the human body and also plays an important role in the regulation of the immune system. Despite its role, it is not found in the entire population.

This antigen is of medical relevance if it is present and has mutations. In the presence of a mutation, autoimmune diseases of the rheumatic form occur more frequently. For this reason, the determination of the status of HLA-B27 is an important criterion in the diagnosis and differential diagnosis of certain diseases.However, the detection of the antigen is not a direct proof of disease, as the person affected does not necessarily have to be ill. Diseases that are particularly common with positive HLA-B27 status include ankylosing spondylitis, Reiter’s disease, rheumatoid arthritis and inflammation of the eye.

In addition, the presence of HLA-B27 provides a certain protection against the outbreak of AIDS. The causes of the connections are not known. You can find additional information on the above-mentioned clinical pictures at

Bechterew’s disease
Rheumatoid Arthritis
Reiter’s syndrome
Inflammation of the eye – How dangerous is it?

The antigen HLA-DR also plays an important role in the function of the immune system.

One of its main tasks is the recognition of foreign substances, which can originate from pathogens such as bacteria, for example. For this purpose, these substances are bound on the surface of the cells by the HLA-DR. Upon contact with immune cells, they are activated.

In addition, the HLA-DR plays an essential role in the success of an organ transplant in the first six months after transplantation. For this reason, the structure of the antigen of the organ donor and recipient must be as similar as possible. At the same time, the gene coding for HLA-DR shows a very high variability.

Therefore the HLA-DR also has a high variability, which makes the search for the same donor and recipient antigen more difficult. Furthermore, as with HLA-B27, the presence of the antigen is associated with the occurrence of some diseases. However, the detection of the antigen is also not synonymous with the onset of the disease.

These diseases include anemia, rheumatoid arthritis, some forms of diabetes, some kidney diseases, an underactive thyroid gland and many more. HLA-DQ2 is an antigen inherited from parents and is found on the surface of most cells in the body. Among other features, HLA-DQ2 plays an important role in the development of celiac disease, an autoimmune disease of the intestine with an intolerance to gluten.

A mutation in the affected gene is decisive for the development of the disease. It is present in up to about 30% of the population in Central Europe. However, the occurrence of the antigen is not the same as the actual disease, since not all persons with the characteristic develop celiac disease.

However, the risk of developing celiac disease is increased if one or both parents have the disease. In this case the risk of inheritance is up to 15%. Due to the high incidence of HLA-DQ2 even in healthy people, the detection of the antigen cannot be used to diagnose celiac disease.

Therefore it has a low positive predictive value. In contrast, the negative predictive value is very high. This means that a person in whom the antigen cannot be detected is very likely not to have celiac disease.

Therefore the detection of HLA-DQ2 can only be used to exclude the disease. It is important at this point to also take a look at the main page on celiac disease: What is celiac disease? HLA-B51 is also a surface molecule found on most cells of the human body.

It is responsible for up to 20% of the occurrence of an autoimmune disease, which is classified as rheumatic. This is called Behçet’s disease and has an inherited component. While the disease is very rare in Central Europe, it occurs significantly more frequently in Turkey and Japan.

The HLA-B51 antigen can be detected in up to 75% of patients. At the same time, however, the detection is not a defining factor for the disease. Therefore, even healthy persons can have it and not develop Behçet’s disease during their entire life. Typically, the disease occurs suddenly without a recognizable cause. In contrast to other autoimmune diseases, the diagnosis is not made on the basis of detection of the antigen in the laboratory, but by clinical appearance.