What causes a febrile reaction during a transfusion?

A febrile reaction during a transfusion is primarily caused by the body's immune response to specific components in the transfused blood products. In this context, bacterial lipopolysaccharides and anti-leukocyte antibodies play a crucial role.

Bacterial lipopolysaccharides are components of the cell wall of gram-negative bacteria. If present in the blood product, they can trigger a febrile response as the immune system reacts to what it perceives as an infection. The presence of anti-leukocyte antibodies, which can originate from the recipient's immune system reacting against donor white blood cells, also contributes to this response. When these antibodies bind to leukocytes in the transfused blood, they activate the immune system, leading to the release of pyrogens that cause fever.

In contrast, other options like red blood cell antibodies would typically lead to hemolytic transfusion reactions, which have a different presentation. Electrolyte imbalances can occur during massive transfusion or other rare cases but are not direct causes of febrile reactions specifically. An air embolism, while a serious concern in transfusion practices, does not lead to fever but rather could cause respiratory distress, cardiovascular complications, or other acute symptoms.

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