The role of adhesion molecules and chemokines in homeostasis and pathologic processes in transplanted organs

Publisher SummaryThis chapter discusses about adhesion molecules, natural and adaptive immunity, and the organs and tissues of the immune response. Adhesion molecules mediate cell adhesion to their surroundings and to neighboring cells. In the immune system, adhesion molecules are critical to most aspects of leukocyte function, including lymphocyte recirculation through lymphoid organs, leukocyte recruitment into inflammatory sites, antigen-specific recognition, and wound healing. There are five principal structural families of adhesion molecules. Natural or innate immunity comprises the inborn immune mechanisms that do not depend upon previous exposure to an antigen. It is present from birth and is designed to protect the host from injury or infection without any previous contact with the infectious agent. Adaptive or acquired immunity is the protection mechanism from an infectious disease agent as a consequence of clinical or subclinical infection with that agent; or by deliberate immunization against that agent with products from it. This type of immunity is mediated by B and T cells, following exposure to a specific antigen. The immune system is found throughout the body and is made up of many different cells, organs, and tissues. The organs and tissues of the system can be classified into two main groups: primary lymphoid organs, where lymphocytes are generated and undergo development and maturation; and secondary lymphoid organs and tissues, where mature lymphocytes interact with antigen.