Introduction

Like genetics, immunology is an important foundation of transfusion science. Antibodies can be formed against red cell, white cell, and platelet antigens, causing cell destruction and a variety of immune disorders. This module reviews the core concepts of immunology that are relevant to routine blood banking. It does not cover the complexities of cellular immunity.

Why is understanding immunology so important in transfusion medicine? Just some of the reasons why immunology is relevant are as follows:

• Antibodies against red cell antigens cause hemolytic transfusion reactions (both immediate and delayed).

• Antibodies against white cell antigens are implicated in nonhemolytic febrile transfusion reactions. Cytokines produced by white cells are also implicated in nonhemolytic febrile transfusion reactions. Such patients may require leukoreduced red cell and platelet concentrates.

• Patients with antibodies against platelet antigens may require single donor HLA-matched platelet concentrates .

• Antibodies against red cell antigens cause hemolytic disease of the newborn.

• Autoantibodies against self red cell antigens cause autoimmune hemolytic anemia (cold, warm, and drug-related).

• Antibodies against drugs can cause drug-related positive direct antiglobulin tests, with or without hemolytic anemia.

• Viable donor lymphocytes in transfused products can cause life-threatening graft-versus-host disease in immunocompromised patients.

• Many blood products provide passive immunity, e.g., hepatitis B immune globulin (HBIG); Rh immune globulin (RhIg); intravenous immuneglobulin (IVIg); etc.

• Pretransfusion tests and tests for transmissable diseases are serological methods involving the reactions of antibody and antigen.

Introduction