HLAalloimmunizáció

HLA alloimmunization, also known as HLA sensitization, is a condition in which the immune system of an individual becomes sensitized to human leukocyte antigen (HLA) molecules, which are proteins found on the surface of cells. This sensitization can occur due to previous exposure to foreign HLA antigens, typically from a blood transfusion, organ transplant, or pregnancy. Once sensitized, the immune system can mount an immune response against cells expressing the sensitizing HLA antigens, leading to potential complications in future transplant procedures or pregnancies.

The HLA system is highly polymorphic, meaning it has many different alleles, and this polymorphism is crucial for the immune system's ability to distinguish self from non-self. However, this same polymorphism can also lead to HLA alloimmunization. The most common HLA antigens involved in alloimmunization are HLA-A, HLA-B, and HLA-DR.

HLA alloimmunization can be classified into different types based on the severity of the immune response and the clinical consequences. These include:

1. Low-level alloimmunization: This is often asymptomatic and may not cause any clinical issues.

2. High-level alloimmunization: This can lead to hemolytic transfusion reactions or transplant rejection.

3. Antibody-mediated rejection (AMR): This occurs when antibodies against HLA antigens cause the rejection of a transplanted organ.

The diagnosis of HLA alloimmunization typically involves blood tests to detect the presence of HLA antibodies. Treatment options depend on the severity of the alloimmunization and may include immunosuppressants, plasma exchange, or in some cases, desensitization protocols to reduce the level of HLA antibodies.

Prevention of HLA alloimmunization involves careful selection of blood products and organs for transplantation, as well as the use of immunosuppressants to minimize the immune response to foreign HLA antigens.