Alloimmunisation

Alloimmunisation
Synonyms	Alloimmunization
Pronounce	N/A
Specialty	N/A
Symptoms
Complications	Hemolytic disease of the newborn, Transfusion reactions
Onset
Duration
Types	N/A
Causes	Exposure to foreign antigens
Risks	Blood transfusions, pregnancy
Diagnosis	Blood test
Differential diagnosis	N/A
Prevention	N/A
Treatment
Medication
Prognosis
Frequency
Deaths	N/A

Alloimmunisation (or alloimmunization) is an immune response to foreign antigens following exposure to genetically different cells or tissues. This condition is particularly significant in the context of blood transfusions and pregnancy.

Pathophysiology

Alloimmunisation occurs when the immune system of an individual recognizes and mounts an immune response against antigens from another individual of the same species. These antigens are typically proteins on the surface of red blood cells, platelets, or other tissues. The most common antigens involved in alloimmunisation are those of the ABO blood group system and the Rh blood group system.

When foreign antigens are introduced into the body, the immune system may produce antibodies against these antigens. These antibodies can lead to the destruction of cells bearing the foreign antigens, a process known as hemolysis in the case of red blood cells.

Causes

Alloimmunisation can occur in several clinical scenarios:

Blood Transfusions

During a blood transfusion, if the donor blood contains antigens that the recipient's immune system recognizes as foreign, alloimmunisation can occur. This is why blood typing and crossmatching are critical before transfusions.

Pregnancy

During pregnancy, a mother may become alloimmunised if fetal blood cells enter her circulation and carry antigens that are foreign to her immune system. This is most commonly seen with the RhD antigen, leading to Rh disease or hemolytic disease of the newborn.

Clinical Manifestations

The clinical manifestations of alloimmunisation depend on the context and the specific antigens involved.

Transfusion Reactions

In the context of blood transfusions, alloimmunisation can lead to transfusion reactions, which can range from mild to severe. Symptoms may include fever, chills, back pain, and hemoglobinuria.

Hemolytic Disease of the Newborn

In pregnancy, alloimmunisation can lead to hemolytic disease of the newborn, where maternal antibodies cross the placenta and destroy fetal red blood cells, leading to anemia, jaundice, and in severe cases, hydrops fetalis.

Diagnosis

Diagnosis of alloimmunisation involves serological testing to detect the presence of antibodies against specific blood group antigens. This is typically done using an indirect antiglobulin test (IAT) or Coombs test.

Management

Management of alloimmunisation involves preventing exposure to incompatible antigens and treating any complications that arise.

Prevention

In the context of blood transfusions, careful blood typing and crossmatching are essential to prevent alloimmunisation. In pregnancy, administration of Rho(D) immune globulin to Rh-negative mothers can prevent sensitization to the RhD antigen.

Treatment

Treatment of complications such as hemolytic disease of the newborn may involve phototherapy, exchange transfusion, or intrauterine transfusion in severe cases.

See Also

• Blood transfusion
• Rh disease
• Hemolytic disease of the newborn

External Links

• [Link to relevant medical resources]