Tissue incompatibility

Tissue incompatibility complex immune response to an alien cells, tissues or organs. Tissue incompatibility arose in the process of evolution as the development of protective reactions of the organism from bacteria and other alien biological agents. In the basis of tissue incompatibility lie phenomenon of immunity (see). Tissue incompatibility occurs when different types of transplantation of organs and tissues (see). In the case of hetero - or xenotransplantation (organ transplants from other animal species), the main cause of incompatibility are species differences organisms of the donor and recipient. When Homo - or allotransplantation (transplantation of organs from animals of the same species or from person-to-person) tissue incompatibility due to the individual characteristics specificity of proteins, polysaccharides and lipids of cell. These features are due to the presence in all tissues of the organism to various antigens (see).
Antigenic properties of the organism acquires already in the early stages of fetal development, so the transplantation of embryonic tissue is also accompanied tissue incompatibility, however, in some cases less pronounced.
The reaction is directed to the rejection of the graft, causing his death in a few weeks or even days. This reaction depends on the activity of immunocompetent lymphocytes, reacting to transplant as alien protein. The result is the infiltration of transplant lymphoid cells and termination in him of the blood flow. Starting locally, this reaction is gradually taking generalized character and leads to the rejection of the transplanted organ.
Therefore, when experimental and clinical transplant donor tissue is necessary to take appropriate measures in order to reduce the response of incompatibility. These measures are carried out in two main directions. The first of them - the selection of the donor. It is obvious that the least immunological differences shall be given to those couples donor - recipient, which have not only eliminated the species specificity, but also individual minimized. Such pairs are either brothers and sisters (primarily identical twins), or parents and children, but this does not exclude matches of different antigens in unrelated couples. Currently, the selection of pairs of donor - recipient is made by comparing them transplantation antigens. The second direction of the struggle with the tissue incompatibility is suppressing its various physical or pharmacological means. These include surgical removal of the recipient lymphoid organs, primarily responsible for the immune system (thymus, spleen, regional lymph nodes), the use of drugs that suppress the immune response, and so on, But it must be remembered that these measures at the same time, dramatically reduce the body's resistance to various infections, because the basis of both reactions and tissue incompatibility, and protection from infectious influences are the same immunologic mechanisms.