TCR-aß+ and TCR-Gd+ T lymphocytes in graft and peripheral blood after heart transplantation

In vertebrates a highly complicated system has evolved to respond to invading micro-organisms such as bacteria, viruses, fungi and protozoa, and protect the individual from lethal infections, The same system frustrates the outcome of organ transplantation in seeing the lifesaving new organ as an alien element, judges it as dangerous and tries to eliminate it. This system is called the Immune System and can be divided into two main sections A: the innate immune system and B: the adaptive immune system, The innate immunity is considered to act as a fast, aspecific first line of defence, The adaptive immune response is more specific and becomes active when the first line of defence is not effective enough in eradicating the alien invasion, Recent insights suggest that the innate immunity may have an additional role in determining to which antigens the adaptive immune system will respond and In the nature of that response (reviewed in ref ,), Important parts of the innate immune system are skin, mucosal tissues, the complement system and phagocytes such as macro phages and granulocytes. The specific immune system has two compartments, the humoral immune system, Involved in the production of antibodies (immunoglobulins) by B lymphocytes, and the cellular immune system, involved in killing virus infected host cells and foreign cells by cytotoxic T lymphocytes (CTL) and the activation of B cells and macrophages by soluble mediators, called cytokines, produced by helper T lymphocytes (HTL), The ability of Band T lymphocytes to recognize foreign structures (antigens) specifically, is mediated by antigen-specific receptors on the surface of these cells, Immunoglobulin (lg) molecules are the antigen specific receptors on B lymphocytes, while the T cell receptor (TCR) has this function on T lymphocytes.

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