Use the following choices to answer questions 1 and 2:
a. hemolysis
b. hemagglutination
c. hemagglutination inhibition
d. no hemolysis
e. precipitin ring forms


Patient’s serum, influenza virus, sheep red blood cells, and anti-sheep red blood cells are mixed in a tube. What happens if the patient has antibodies against influenza?

Verified step by step guidance

1. Identify the components involved in the test: patient's serum, influenza virus, sheep red blood cells, and anti-sheep red blood cells.
2. Understand that the test is designed to detect the presence of antibodies against the influenza virus in the patient's serum.
3. Recognize that if the patient has antibodies against influenza, these antibodies will bind to the influenza virus.
4. Consider the role of hemagglutination: the influenza virus can cause hemagglutination by binding to the sheep red blood cells.
5. Determine that if the patient's antibodies bind to the influenza virus, they will prevent the virus from causing hemagglutination, leading to hemagglutination inhibition.

Key Concepts

Hemagglutination

Hemagglutination is a process where viruses, such as the influenza virus, bind to red blood cells (RBCs) and cause them to clump together. This occurs because the viral hemagglutinin protein attaches to sialic acid residues on the surface of RBCs. In the context of the question, if the patient has antibodies against the influenza virus, these antibodies can block the hemagglutination process, preventing the virus from binding to the RBCs.

Antibody-Antigen Interaction

Antibody-antigen interaction is a fundamental concept in immunology, where antibodies specifically bind to antigens (foreign substances) to neutralize or mark them for destruction. In this scenario, if the patient's serum contains antibodies against the influenza virus, these antibodies will specifically recognize and bind to the viral antigens, inhibiting hemagglutination and potentially leading to a lack of clumping of the RBCs.

Hemagglutination Inhibition Test

The hemagglutination inhibition test is a diagnostic method used to determine the presence of specific antibodies in a patient's serum. In this test, if antibodies against a virus are present, they will inhibit the hemagglutination of RBCs by that virus. Therefore, in the context of the question, if the patient's serum contains antibodies against the influenza virus, hemagglutination will be inhibited, indicating a positive reaction.