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The Question
Sunday, February 7, 2010 @ 6:45 AM Question Our immune system tends to mount an immune response to the entry of an antigen from the same species (e.g. renal transplant). Discuss on the factors to be considered to prevent renal transplant rejection. Artificial implants (like pace makers, knee/hip joints) and corneal transplants are not rejected by our immune system? Why? Artificial Implants
@ 6:27 AM   Pacemaker with electrode for transvenous insertion. Device is 4cm long with electrodes that measure between 50- 60 cm. An X- ray image of installed pacemaker showing wire routing. Pacemaker Corneal transplants David A. (2009) Transplant rejection. Retrieved February 4, 2010, from URAC Website: http://www.nlm.nih.gov/medlineplus/ency/article/000815.htm Renal Transplant Rejection
@ 5:28 AM  Transplant Rejection Transplant rejection is when a transplant recipient's immune system attacks a transplanted organ or tissue. Body's immune system protects the body from potentially harmful substances, such as microorganisms, toxins, and cancer cells. These harmful substances have proteins called antigens on their surfaces. If the immune system identifies antigens that are foreign (not part of your body), it will attack them.In the same way, foreign blood or tissue can trigger a blood transfusion reaction or transplant rejection. To help prevent this, tissue is "typed" before the transplant procedure to identify the antigens it contains.Though tissue typing ensures that the organ or tissue is as similar as possible to the tissues of the recipient, the match is usually not perfect. No two people (except identical twins) have identical tissue antigens. Immunosuppressive drugs are needed to prevent organ rejection. Otherwise, organ and tissue transplantation would almost always cause an immune response and result in destruction of the foreign tissue.There are some exceptions, however. The immune system is the military defense system for our body, with specialized cells and proteins that search and destroy invading organisms. The immune system develops the ability to determine normal parts of our bodies (self) from invading or damaged parts of our body (non-self). When bacteria, viruses or other infectious agents invade, the immune system rapidly recognizes these organisms as foreign and a set of cells and proteins rapidly learn how to effectively and efficiently kill the invading organism. After having received this special training, these cells and proteins maintain an immunologic memory so that if encountered again in the future these organisms are rapidly killed. Under normal circumstances, when we are exposed to an infectious agent for the first time, we develop an infection but our immune system rapidly develops the ability to kill these infecting organisms and the infection ends. If we encounter the same organism again, the immune system is primed and ready to kill these organisms so that a second infection with the same organism seldom occurs. It is just this system that is so important to maintaining our health in a world full of germs that causes problems for transplant patients. When a transplanted organ is placed into a patient's body, his normal immune system recognizes the tissue as foreign, assumes it is an invading organism and begins to develop the ability to attack and kill these foreign cells. This process is transplant rejection. Repeated Transplant Rejection: Why Does It Happen? (2002). Retrieved May 3, 2010, from American Association of Kidney Patients. Website: http://www.aakp.org/aakp-library/Repeated-Transplant-Rejection/ Rapamune To Prevent Kidney Transplant Rejection To help reduce the risk of organ rejection, transplant patients are given a life-long regimen of immunosuppressant agents. These drugs are intended to lower the body’s normal immune response, allowing the transplanted organ to remain functional. Immunosuppressant drugs are necessary after organ transplants because the human body is designed to reject cells that are foreign and perceived to be potentially dangerous, such as a transplanted organ. Thus, the very system that provides protection against intruding organisms is the system that poses a substantial threat to the transplant recipient. FDA Approves Rapamune To Prevent Kidney Transplant Rejection. (1995). Retrieved May 3, 2010, from Doctor’s Guide. Website: http://www.pslgroup.com/dg/12c216.htm Medicines that Prevent Rejection All patients who receive an organ transplant are considered for some form of treatment to prevent rejection of the organ. For kidney transplant patients, the choices of medicines and various combinations of drugs have led to remarkably good outcomes with expectations that almost every kidney transplant should work. This does not mean that rejection cannot or does not occur. However, it is far rarer than it used to be, and it is much more easily treated and reversed than in the past. The most common cause of rejection in modern kidney transplantation is that the patient does not follow the medication treatment plan. Most transplant centers have excellent treatment plans, or “protocols,” which define the way they use the various anti-rejection medicines. Patients may hear that a particular transplant center has a “Cyclosporin-based protocol,” or “Rapamune-based protocol,” or other such name. The term “protocol,” as used in day-to-day medicine, simply means a defined treatment plan. For some centers, and in some patient populations, these treatment plans do not change much from patient-to-patient. In other instances, protocols are designed so that a center would use different drugs in different types of patients or would change drugs for any particular patient as time went on. The medications that prevent rejection can be given to patients just before a kidney transplant, although that does not often occur. All patients are started on some type of medicine at the time of or shortly after the kidney transplant operation. Medicines are scheduled usually for once or twice a day doses, and the timing of certain medications remains an important part of treatment. The selection of drugs and various doses is a bit different in the immediate post-transplant period while the patient is in the hospital, as compared to the outpatient/long-term care setting. In addition, medicines given in the hospital are monitored by staff so patients have a lesser role in directing their own drug use. Medications used principally in the outpatient setting are often given in some combination so that patients are taking two or three anti-rejection drugs. These medications usually have several different names for the very same drug. Transplant Drugs: Medicines That Prevent Rejection. (2003). Retrieved May 3, 2010, from American Association of Kidney Patients. Website: http://www.aakp.org/aakp-library/Transplant-Drugs/ Symptoms The organ does not function properly General discomfort, uneasiness, or ill feeling Pain or swelling in the location of the organ (rare) Fever (rare) The symptoms vary depending on the transplanted organ or tissue. For example, patients who reject a kidney may have less urine, and patients who reject a heart may have symptoms of heart failure. Treatment The goal of treatment is to make sure the transplanted organ or tissue functions properly, while at the same time suppressing the recipient's immune response. Suppressing the immune response can treat and prevent transplant rejection. Many different drugs can be used to suppress the immune response. The dosage of the medication depends on the patient's status. The dose may be very high while the tissue is actually being rejected, and then reduced to a lower level to prevent it from happening again. Prevention ABO blood typing and HLA (tissue antigen) typing before transplantation helps to ensure a close match. Suppressing the immune system is usually necessary for the rest of the transplant recipient's life to prevent the tissue from being rejected. Being careful to take post-transplant medications properly and being closely monitored by your doctor may help prevent rejection. Transplant Rejection. (2009). Retrieved May 3, 2010, from Medline Plus Medical. Website: http://www.nlm.nih.gov/medlineplus/ency/article/000815.htm |
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