Questions and Answers
What does ELISA stand for?
Enzyme-Linked Immunosorbent Assay.
What are ELISA assays used for in labs?
To determine if a particular antibody is present in a patient's blood sample.
What test can be used to determine whether a patient has an infectious or autoimmune disease?
An ELISA test.
What does a positive result indicate?
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The watery fluid of the blood is called?
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Once isolated, the secondary antibody can be?
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What happens when the appropriate chemical (substrate) is added?
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How is the test quantified?
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What does the amount of color reflect?
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What is systemic lupus erythematosus (SLE)?
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What are the four steps of an ELISA protocol?
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What does a centrifuge do?
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What are you preparing in step 2 and why are there three different solutions?
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What has the ELISA plate been pretreated with and why?
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What is the positive control?
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What is a primary antibody?
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What is the negative control?
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Why is it necessary to have a positive and a negative control?
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Why incubate the plate in step 5?
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Why wash the plate?
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What is a secondary antibody?
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What is the attached enzyme in this assay?
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What is the specific substrate for HRP and what color does it produce?
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How can the yellow color be quantitatively measured, and at what wavelength?
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What do the results indicate?
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How is this same test used to test for the presence of HIV?
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Study Notes
ELISA Overview
- Stands for Enzyme-Linked Immunosorbent Assay, a common laboratory technique.
- Used to determine the presence of specific antibodies in a blood sample.
- Can diagnose infectious or autoimmune diseases.
ELISA Results Interpretation
- A positive result indicates an antibody is present, suggesting the person has the disease.
- The color intensity produced in the test correlates with the concentration of the antigen.
Serum and Controls
- Serum is the watery fluid extracted from blood after centrifugation.
- Positive control: anti-DNA primary antibody.
- Negative control: buffer to ensure reliability of results.
ELISA Steps
- Step 1: Samples are bound to a support and centrifuged to separate phases.
- Step 2: Different dilutions of samples are prepared for accurate antibody level determination.
- Step 3: Primary antibody is added to bind to the antigen; excess is washed away.
- Step 4: Secondary antibody-conjugate is added, allowing for detection.
- Step 5: Incubation ensures proper interaction between antibodies and antigens.
- Step 6: Plate washing removes unbound antibodies.
- Step 7: Secondary antibody, from a different species, is added along with HRP enzyme.
Significance of Color Change
- Substrate for HRP is ABTS, producing a yellow color which can be measured.
- Color is quantitatively analyzed at a wavelength of 414 nanometers.
Application for Disease Testing
- Systemic lupus erythematosus (SLE) is an autoimmune condition detected via ELISA.
- For HIV testing, a similar ELISA protocol can be followed with different reagents.
Patient Results Interpretation
- Results for hypothetical patients indicate likely disease presence:
- Patient A: Likely has SLE/HIV.
- Patient B: Unlikely to have SLE/HIV, further testing needed.
- Patient C: Probably does not have SLE/HIV.
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Description
This quiz covers the fundamentals of the Enzyme-Linked Immunosorbent Assay (ELISA), a vital lab technique for detecting antibodies in blood samples. It includes the interpretation of results, understanding serum controls, and the step-by-step procedure of the ELISA process. Test your knowledge of this important diagnostic tool!