Surgical Transplant

Once surgeons acquired the ability to sever and reconnect arteries, the ability to control the immune system has been the primary concern in transplant surgery. The immune system is a complex biological network intricately linked to cells found in the blood. Many individuals share similar antigens, (small molecular proteins found on the surface of tissues that can stimulate an immune response,) and one of the first goals is to match antigens between organ donors and the recipients. The idea is to increase the likelihood that the patient's immune system will not attack because it recognizes a foreign antigen in the donor tissue.

Scientists have identified six primary types of antigens, called histocompatibility-locus antigens. Transplantation between people whose tissues and organs share all of these antigens generally is successful. For example, family members, particularly identical twins, usually have the same antigens. (In fact, the first successful kidney transplant was performed in 1955 when a young man received one of the kidneys of his twin brother.) As a result, relatives are often the source of donor tissues for patients who need kidneys and bone marrow transplants because one kidney or some bone marrow can be donated without causing harm to the donor.

As the number of matching antigens between donor and recipient decreases, the need to suppress the immune system with drugs becomes increasingly important. Unfortunately, many of these drugs have side effects and can suppress the immune system to the point that the patient becomes susceptible to other infections and diseases, which can cause the transplant to be rejected and lead to the patient's death. The advantage of cyclosporin is that it can be targeted somewhat to work in specific tissues and organs of the body, thus keeping the patient from becoming entirely immunocompromised, which can lead to death from any number of diseases and infections not directly related to the transplanted organ's functioning.