Final answer:
The correct sequence for an acute hemolytic reaction due to a blood transfusion is sensitization, followed by antibody binding, complement activation, and finally hemolysis. This is a type II hypersensitivity reaction.
Step-by-step explanation:
An acute hemolytic reaction is a severe and potentially life-threatening condition that occurs when there is an incompatibility between the blood types of a blood transfusion recipient and the donor. The correct sequence for an acute hemolytic reaction due to a transfusion is: sensitization, antibody binding, complement activation, and hemolysis. This is a type II hypersensitivity reaction where the recipient's immune system reacts against the donor's red blood cells (RBCs). Here's a brief overview of the process in four steps:
- Sensitization: The immune system of the person receiving the blood transfusion encounters the foreign antigens on the transfused RBCs.
- Antibody Binding: Antibodies in the recipient’s blood specifically bind to these foreign antigens on the RBCs.
- Complement Activation: The bound antibodies trigger the complement system, which is a group of proteins that aid in the destruction of pathogens.
- Hemolysis: Activation of the complement cascade leads to the destruction of the RBCs, releasing hemoglobin and potentially causing further complications.
This sequence of events is highly regulated and each step is crucial for the subsequent action. The role of complement in mediating the lysis of RBCs is particularly important. It starts with the binding of the antibody to the antigen, which triggers the rest of the cascade, eventually culminating in the formation of the membrane attack complex and subsequent cell lysis.