The Immune System and Transplantation (Magill’s Medical Guide, Sixth Edition)
Transplantation antigens are proteins expressed on the surface of an individual’s cells. Every individual has a unique set of these proteins, called human leukocyte antigens (HLAs), which are encoded on chromosome 6. Each parent contributes one HLA-containing chromosome, and both chromosomes are expressed in the offspring. The purpose of these antigens is to help the body recognize what is “self” and what is not. In this manner, bacteria and other pathogens harmful to the individual can be sensed as “nonself” and destroyed by the immune system.
When an organ is transplanted between unrelated people (allotransplantation), it will not be recognized as self in the recipient’s body, and the immune system will start to attack it in a process called rejection. In the same way, transplants between identical twins, with the same HLA proteins on their cells, will be recognized as self and not be rejected.
White blood cells (lymphocytes) are intimately involved in the body’s immune response. They protect the individual from invading bacteria, viruses, and fungi. Lymphocytes can be divided into two subsets: B and T cells. The T cell is the main cell involved in the recognition and destruction of allotransplants. Receptors found on the T lymphocyte cell surface are stimulated by the foreign antigens found on allotransplants. With T-cell stimulation, events are initiated that lead to the...
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Indications and Procedures (Magill’s Medical Guide, Sixth Edition)
With the advent of dialysis in 1960, renal failure is no longer fatal and patients can live by having their blood filtered several times per week. Kidney transplantation, however, offers a significant improvement in the quality of life compared with dialysis. Unfortunately, while more than 9,000 patients in the United States receive kidney transplants each year, another 8,500 patients remain on waiting lists. With only 13 percent of potential donors actually being utilized, there is much room for greater success.
Two donor options are available to the recipient awaiting a kidney transplant: living related and cadaveric. The first option involves removing a kidney from a willing family member and transplanting it into the recipient. Removing one of two donor kidneys does not significantly affect a healthy individual. The second option is for the recipient to be placed on a waiting list for a cadaveric kidney. When a cadaveric kidney that is of a compatible blood type for a particular recipient becomes available, arrangements are made to admit this patient to the hospital for transplant.
Approximately 25 percent of all kidney transplants are living related. The advantages of a living related transplant are twofold. First, the waiting period for a cadaveric kidney is eliminated, as the operation can be scheduled as soon as the recipient has been evaluated. Second, kidneys from living related donors tend to work...
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Perspective and Prospects (Magill’s Medical Guide, Sixth Edition)
There are a number of ethical problems connected to organ transplantation. Primary among these is the problem of donor selection. Cadaverous donors sometimes present the problem of whether sufficient permission was given to donate organs. Without full consent of the donor, it is considered unethical to harvest tissues. In cases where the potential donor died without giving consent, very often relatives who knew of their wish will give consent in their stead. In the case of living donors who are donating kidneys or bone marrow, questions will sometimes arise of their ability to give full consent; for example, whether the donor is fully competent and informed of what consent means. These questions of competence will usually arise with the mentally ill, but often arise when the donor potentially has been coerced by physicians or relatives. Coercion on anyone’s part eliminates full consent from the donor.
Another recent ethical dilemma is the use of human newborns or late stage embryos as organ donors. Is it ethically permissible to use a fetus as an “organ farm”? There have been reports in the last several years of parents with a terminally ill child conceiving another child to act only as an organ donor. Although most often these donor infants become family members, they are sometimes aborted because the needed organ can only be obtained in that way. The bioethicist Mary Anne Warren has argued that the mere...
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For Further Information: (Magill’s Medical Guide, Sixth Edition)
Brunicardi, F. Charles, et al., eds. Schwartz’s Principles of Surgery. 9th ed. New York: McGraw-Hill, 2010. A chapter reviewing most aspects of surgical transplantation is provided in this text. The section on transplant immunology is particularly excellent, with most of the important terms clearly defined.
Chopra, Sanjiv. The Liver Book: A Comprehensive Guide to Diagnosis, Treatment, and Recovery. New York: Simon & Schuster, 2002. Covers a great deal of information about liver disorders, including how doctors diagnose liver ailments, what to expect from tests and screening, hepatitis B and hepatitis C, liver transplants, and the role of alternative treatments.
Mulholland, Michael W., et al., eds. Greenfield’s Surgery: Scientific Principles and Practice. 4th ed. Philadelphia: Lippincott Williams & Wilkins, 2006. Covers the scope and practice of surgery and includes reviews of the management of trauma and transplantation, surgical practice according to anatomic region and specialty, and musculoskeletal, neurologic, genitourinary, and reconstructive surgery.
National Research Council. Institute of Medicine. Stem Cells and the Future of Regenerative Medicine. Washington, D.C.: National Academy Press, 2002. A lay exploration of the scientific and ethical debate surrounding stem cell research, as well as an overview of medical advances and leading...
(The entire section is 407 words.)