Medical Laboratory Scientist (MLS) ASCP Practice Exam

HLA antibodies are primarily associated with febrile nonhemolytic transfusion reactions. These reactions occur due to the recipient's immune response to white blood cell (WBC) antigens, specifically human leukocyte antigens (HLA), present in the transfused blood products. When the recipient has pre-existing antibodies against these HLA antigens, they may mount an immune response, leading to fever and chills after the transfusion.

This type of reaction is characterized by an increase in body temperature, often accompanied by other symptoms such as chills, rigors, and sometimes hypotension. The mechanisms involved are primarily related to the activation of the recipient’s immune system in response to foreign WBC antigens. Identifying the presence of HLA antibodies in the recipient is a significant factor in anticipating and potentially preventing this type of transfusion reaction.

In contrast, other reactions listed, such as acute hemolytic transfusion reactions and delayed hemolytic transfusion reactions, are typically associated with blood group antibodies (like ABO or Rh antibodies) rather than HLA antibodies. Allergic transfusion reactions may also involve different pathways, primarily linked to IgE-mediated responses against plasma proteins or allergens, rather than being directly correlated with HLA antibodies.