Specific transplantation tolerance

Article Abstract:

One goal of transplantation immunology has been to 'teach' the immune systems of adult animals to selectively tolerate certain antigens, so that, for instance, patients who receive transplanted organs will not have to take immunosuppressive drugs for the rest of their lives. While this is necessary to prevent graft rejection, these drugs have important side effects, including enhancing patients' susceptibility to cancer and infections. If immunological tolerance to specific antigens associated with transplantation could be induced, immunosuppressive drugs could be, at least theoretically, eliminated. An article in the October 24, 1991 issue of The New England Journal of Medicine reports results indicating that specific transplantation tolerance can be induced in kidney recipients by blood transfusions from immunocompatible donors. Nine of 10 patients with at least one similar human leukocyte antigen (HLA) subtype to the blood donor lost their T-cell response (the production of cytotoxic T cells) after transfusion. The mechanisms of this induced nonresponsiveness remain to be clarified. One possibility, clonal deletion, is that T cells with receptors that would react with the donor's transplantation antigens are eliminated. Another, clonal anergy, is that this class of T cells is inactivated but not eliminated. The third possibility is active immunologic suppression, which would require the presence of specific cell-suppressive populations that can inhibit reactive T cells. The second explanation is preferred by the authors of the research article. If the findings are confirmed, the possibility of inducing specific tolerance holds great theoretical and clinical promise. Such tolerance has been induced in several animal models, but the methods of induction used in these studies have not been applied to humans. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Research, Blood transfusion, Transplantation immunology, Histocompatibility, editorial

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Improving the success of organ transplantation

Article Abstract:

A new class of immunosuppressive drugs is being developed to prevent organ transplant recipients from rejecting their transplant. They are monoclonal antibodies formed against very specific parts of the immune system. Most were directed against T cells, but newer ones are directed against part of a T cell receptor. A monoclonal antibody against the interleukin-2 receptor on T cells can reduce the incidence of organ rejection in patients receiving a heart transplant. Another study shows that the survival of transplanted organs has increased since 1988.

Editorial, Analysis

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Photopheresis for the prevention of rejection in cardiac transplantation

Article Abstract:

Photopheresis in addition to immunosuppressant drugs appears to reduce the rate of organ rejection. Photopheresis is a complicated technique that suppresses the activity of T cells in the recipient that would cause the body to reject a donor organ. Researchers randomly assigned 60 people who received a heart transplant to take three immunosuppressive drugs alone or the three drugs plus photopheresis. The rate of organ rejection was lower in the patients who had photopheresis. Survival rates were similar in both groups as was the rate of infection.

Evaluation, Heart, Heart transplantation

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