Antigen-Antibody Reactions & Tests

Question 1

What is prozone?

Answer 1

Excess antibody

Pros have good bodies!

Question 2

What is postzone?

Answer 2

Excess antigen

Question 3

RIST and RAST are what type of tests?

Answer 3

Radioimmunoassays for detecting antibody and antigen

Question 4

Radioimmunosorbent Test (RIST) tests for what?

Answer 4

Measures total IgE

Question 5

Radioallergosorbent Test (RAST) tests for what?

Answer 5

Measures IgE to speific allergens

Question 6

What could lead to a false positive result in ELISA?

Answer 6

Failure to wash between each step

Question 7

What is the basic principle of Radial Immunodiffusion (RID)?

Answer 7

A circle of precipitated antigen and antibody forms, and continues to grow until equilibrium is reached.

Question 8

What is the basic principle of double diffusion (ouchterlony)?

Answer 8

Determine relationship between antigens and antibodies by looking at double diffusion patterns.
Patterns: identity, non-identity, partial identity

Question 9

What is the basic principle of immunoelectrophoresis? (IEP)

Answer 9

Gel diffusion + electrophoresis. Most commonly used to determine which heavy or light chains are involved.

Question 10

What would you see in serum immunoelectrophoresis (IEP)?

Answer 10

Monoclonal gammopathies (single class and type of immunoglobulin)

Question 11

What would you see in urine immunoelectrophoresis (IEP)?

Answer 11

Bence jones protein (monoclonal gammopathy)

Question 12

What is the basic principle of immunofixation?

Answer 12

Protein electrophoresis + immunoprecipitation.

Very sensitive, easy to read.

Used to classify monoclonal gammopathies (determine heavy and light chains involved)

Question 13

What is the basic principle of rocket immunoelectrophoresis? (Laurel)

Answer 13

Similar to radial immunodiffusion (RID) but electrophoresis is used to speed formation of precipitate.
» Cone shape area of precipitation forms that looks like a rocket

Question 14

HIV testing, serum HcG, hepatitis antigen and antibody testing, and antibodies to bacteria and viruses are implemented with what type of immunoassay?

Answer 14

Enzyme immunoassay (EIA/ELISA)

Question 15

What is the basic principle of enzyme multiplied immunoassay (EMIT)?

Answer 15

Used to measure concentrations of drugs and hormones

Positive test: color produced; drug in patient serum
Negative test: no color produced

Question 16

What is the basic principle of nephelometry?

Answer 16

Determine concentration of antibody or complement using scattered light

Question 17

What is the basic principle of fluorescence polarization immunoassay (FPIA)?

Answer 17

Add reagent antibody and fluorescent tagged antigen to patent serum

Question 18

Serial dilutions: When does testing for infectious diseases happen?

Answer 18

On acute and convalescent specimens collected about 2 weeks apart

Question 19

In a serial dilution, what fold in titer must you see for it to be clinically significant?

Answer 19

4-fold or 2 tube rise in titer for it to be clinically significant

Question 20

What is the difference between SENSITIVITY and SPECIFICITY?

Answer 20

Sensitivity: Ability of a test to detect very small amounts of a substance; ability of a test to give positive results if patient has the disease.

Specificity: Ability of test to detect substance without interference; ability of test to give negative result if patient does not have disease

Question 21

What immunology tests are more sensitive?

Answer 21

Non-Lattice (More sensitive) 0.001 mg/mL

• RIA (Radial immunoassay)
• EIA (Enzyme immunoassay)
• FIA (Fluorescent immunoassay)
• Nephelometry

Question 22

What immunology tests are less sensitive?

Answer 22

Lattice –> Less Sensitive ~500 mg/ml

• Complement fixation
• Agglutination
• Flocculation / Precipitation
• Rocket Electrophoresis
• RID (Radial immunodiffusion)
• Ouchterlony (Double immunodiffusion)
• IFE (Immunofixation)
• IEP (Immunoelectrophoresis)