| Popis: |
Physicians have long considered the transplantation of tissue and organs to individuals with various pathologies to be the Holy Grail. Initially they were faced with technical issues such as maintaining viability in organs removed from donors and anastomosing blood vessels. These issues were solved during the first half of the twentieth century, and in 1954, Joseph Murray and colleagues performed the first successful kidney transplant between identical twins. Subsequently the problem of immunologic rejection needed to be addressed. Although transplantation of relatively avascular tissue (cornea) was successful, the transfer of vascularized organs between donors and recipients who were not genetically identical routinely failed. Studies in the early 1900s demonstrated that transplanted tumors expressed cell surface antigens that stimulated adaptive immune responses. In the 1940s and 1950s, Peter Medawar showed that rejection of healthy tissue was due to an immunological reaction and that the antigens responsible for inducing this response were the same as those involved in tumor rejection. Further studies revealed that these antigens are coded for by genes in the major histocompatibility complex. The destructive reaction involves activation of T lymphocytes in the recipient. This knowledge led to the development of several drugs that can control these responses and has made organ transplantation the success it currently is. |
