Abstract
Each blood transfusion exposes the recipient to the hazards of immunisation to histocompatibility antigens as well as white cell and platelet antigens. As the number of transfusions received by a patient increases so too does the likelihood of the development of antibodies which may by their multispecific character effectively prevent lifesaving therapy in the future. Special steps can and should be taken to minimise the risks of immunisation in the group of patients who will be dependent on long term transfusion therapy. An extension of knowledge about the antigenic systems of leucocytes and platelets, including HLA, and the introduction of more specific tests for the detection of antibodies directed against them should assist in the provision of more appropriately matched blood components.