One of the priority tasks in preparing a recipient for transplantation is to conduct thorough laboratory tests to select a donor-recipient pair, which is aimed at overcoming the individual immunological barrier of the recipient. This was reported at the National Scientific Center of Surgery and Transplantation named after O.O. Shalimov, UNN reports.
According to the Center, transplantation is currently the only way to treat end-stage renal, hepatic, cardiac, pulmonary, and pancreatic failure. The benefits of organ transplantation coexist with the risks of the surgical procedure itself, in particular, with immunological risks that must be inhibited by immunosuppressive drugs for life.
The stability of the individual immunological barrier is ensured by a system of antigens, the so-called human leukocyte antigens (HLA). These are receptor complexes located on the surface of each nuclear cell in our body. In the presence of a genetically alien HLA complex, these cells are immediately activated, multiply and acquire cytotoxic properties and form specific antibodies to neutralize tissues with a foreign HLA, the Center for Surgery and Transplantation noted.
The absence of donor-specific HLA antibodies in the recipient and complete matching of HLA antigens between the donor and recipient ensure the most successful selection of the donor-recipient pair, which is the key to successful transplantation, which will significantly reduce the risk of rejection and ensure stable and long-term function of the transplanted organ
It is noted that donor-recipient matching is carried out only in specialized laboratories that are equipped with special equipment and are staffed by specialists with appropriate qualifications who work around the clock (24/7). In Ukraine, there are only a few such fully functioning laboratories, mainly due to the lack of relevant specialists and immunologists with specializations in transplant immunology. In particular, such a laboratory was created at the Shalimov Center for Surgery and Transplantation.
When a potential recipient of a solid donor organ is placed on the so-called "Waiting List" at a transplant center, a molecular genetic test, HLA typing, is performed, which ensures the automatic selection of a donor with the appropriate HLA genotype.
HLA antibody screening is also performed, which allows to automatically rank potential recipients into general and priority recipients, and provides important information about the need for additional preparation of such a recipient. This test is called the Panel Reactive Antibody (PRA Test).
If the percentage of PRA is more than 20%, an extended test is performed to determine the specificity of such HLA antibodies in order to avoid transplantation of an organ with HLA antigens specific to the recipient's existing HLA antibodies when selecting a potential donor. In other words, this test allows us to determine to which HLA antigens of a potential donor the recipient has antibodies in order to avoid so-called antigen-antibody matches.
Immediately before the transplantation of a solid organ, a test is performed to determine donor-specific antibodies. As noted, this is one of the most important studies, the need for which makes it impossible to have an acute rejection of a solid organ on the operating table. Such a test is called Complement Dependent Cytotoxicity - CDC test or more commonly known as Cross-match Test.
Testing for the presence of donor-specific antibodies formed after transplantation should be performed every 3-6 months for renal allograft recipients, and once a year for recipients of other organs. The reason for urgent screening or for the presence of specific HLA antibodies is to verify the rejection reaction of the donor organ.
At the same time, the diagnosis of rejection is verified if there are clinical manifestations of donor organ dysfunction, HLA antibodies and an increase in cytotoxic lymphocytes in the recipient's peripheral blood (blood immunogram). The "gold standard" for this verification is a puncture biopsy, the results of which indicate that HLA antibodies directly destroy the cells of the donor organ.
Thus, laboratory tests for histocompatibility are a priority in transplantation, the thoroughness of which determines the duration of the transplanted organ functioning and the quality of life of the recipient in general