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Ch. 18 - Practical Applications of Immunology
Tortora - Microbiology: An Introduction 14th Edition
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook
All textbooksTortora 14th EditionCh. 18 - Practical Applications of ImmunologyProblem 1
Chapter 18, Problem 1

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?

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1
Step 1: Identify the components in the mixture: patient's serum (which may contain antibodies), influenza virus, sheep red blood cells (RBCs), and anti-sheep RBC antibodies.
Step 2: Understand the principle of hemagglutination: influenza virus can cause hemagglutination by binding to receptors on sheep RBCs, causing them to clump together.
Step 3: Consider the role of patient antibodies against influenza: if present, these antibodies will bind to the influenza virus and block its ability to agglutinate the sheep RBCs.
Step 4: Recognize that when antibodies block hemagglutination, this is called hemagglutination inhibition, meaning no clumping of RBCs will occur.
Step 5: Conclude that in this test, if the patient has antibodies against influenza, the expected outcome is hemagglutination inhibition (choice c).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Hemagglutination

Hemagglutination is the clumping of red blood cells caused by viruses or antibodies binding to antigens on the cell surface. Influenza virus can cause hemagglutination by attaching to sialic acid receptors on red blood cells, leading to visible clumping in a test tube.

Hemagglutination Inhibition

Hemagglutination inhibition occurs when antibodies specific to a virus bind to viral particles, preventing them from attaching to red blood cells. This stops hemagglutination, indicating the presence of antibodies against the virus in the patient’s serum.
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Role of Anti-Sheep Red Blood Cell Antibodies

Anti-sheep red blood cell antibodies bind specifically to sheep red blood cells, causing hemolysis or agglutination. In this test, they help differentiate reactions involving sheep RBCs, clarifying whether hemolysis or agglutination is due to viral or antibody activity.
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Related Practice
Textbook Question

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, Chlamydia, guinea pig complement, sheep red blood cells, and anti-sheep red blood cells are mixed in a tube. What happens if the patient has antibodies against Chlamydia?

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Textbook Question

Define the following terms, and give an example of how each reaction is used diagnostically:

a. Viral hemagglutination

b. Hemagglutination inhibition

c. Passive agglutination

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Textbook Question

Classify the following vaccines by type. Which could cause the disease it is supposed to prevent?

a. Attenuated measles virus

b. Dead Rickettsia prowazekii

c. Vibrio cholerae toxoid

d. Hepatitis B antigen produced in yeast cells

e. Purified polysaccharides from Streptococcus pyogenes

f. H. influenzae polysaccharide bound to diphtheria toxoid

g. A plasmid containing genes for influenza A protein

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Textbook Question

Label the components of the direct and indirect FA tests in the following situations. Which test is direct? Which test provides definitive proof of disease?

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