5th IS

Which of the following does not describe Primary Binding Tests ?

1- complexes formed are separated from the uncombined antigen and antibody and the amount of label in these immune complexes is estimated

2- markers like radioisotopes are used to identify one of the reactants

3- can be measured using immunohistochemical techniques

4- binding of the antigen and antibody will occur longer

• 1,2,3

• 1 and 3

• 2 and 4

• 4 only

TRUE about Solid-Phase RIA Competitive Assay:

1-The concentration of the patient’s sample is indirectly proportional to the amount of

radioactive labelled antigen attached to the antibody

2-Antiigens are incubated with protein A coated solid phase to block non-specific binding sites 3-Radioactivity in the bound phase and/or the free phase is quantitatively measured

4-RAST is an example of the assay

• 1,2,3

• 1 and 3

• 2 and 4

• 4 only

The following are true of the first phase of serological reaction:

1-aggregates develop

2-can combine in the absence of electrolytes

3-does not occur when monovalent antibodies are involved in the reaction

4-uses tagged reagents for the reaction to be detected

• 1,2,3

• 1 and 3

• 2 and 4

• 4 only

Which of the following statements best describes Paper Radioimmunosorbent (PRIST)?

• used for the direct measurement of IgE globulin

• is a competitive assay

• is performed by incubating a specific allergen-coated

• particles with the patient serum

Which of the following are true of Enzyme Linked Immunosorbent Assay?

1- make use of nine enzymes which converts a colorless substrate to a colored product indicating the presence of antigen-antibody binding

2- can be used to detect or measure either antigen or antibody

3- employs the Indirect, Sandwich and Competitive ELISA

4- enzyme activity is generally determined spectrophotometrically

• 1,2,3

• 1 and 3

• 2 and 4

• 4 only

• All of the choices

Which of the following items are true of the Antibody Sandwich Immunoassay?

1-are designed to measure the antigen in the biological sample and antibodies are referred as capture antibodies are affixed to the solid phase

2-first antibody is the one specific for the antigen being assayed

3-second antibody is a precipitating antiglobulin which binds to epitopes in the Fc region of the primary antibody

4-is a noncompetitive direct RIA binding technique

• 1,2,3

• 1 and 3

• 2 and 4

• 4 only

• All of the choices

All of the following statements describe Sandwich ELISA, EXCEPT:

• is used to determine the antigens such as tumor markers, hormones and serum proteins

• Antigen in the sample binds with the capture antibody on the microwell and becomes immobilized

• Substrate product concentration is inversely proportional to the concentration of standard or test antigen added

• Pregnancy test used to detect the presence of HCG is an example of the assay

Which of the following is NOT TRUE of Indirect ELISA?

1-Detection of the HIV and HCV antibodies is an example of the assay

2-Washing is an important step to remove unbound reagent and antibody

3-A colored product is measured spectrophotometrically after incubation with the substrate which is directly proportional to the amount of the antibody in the sample

4-After addition of the enzyme-linked antiglobulin if the antibody is present in the sample it will bind with the Fab region of the unknown antibody

• 1,2,3

• 1 and 3

• 2 and 4

• 4 only

Which of the following is true of Enzyme-Multiplied Immunoassay?

• It is a non-classical competitive immunoassay, does not use a solid phase and eliminates numerous washing steps

• frequently used to test for the presence of small molecules such as drug metabolites in urine

• a colored product indicates the presence of drug in the patient’s urine

• all of the above

Which of these is NOT true to Chemiluminescent Immunoassay?

• is an immunoassay in which a chemiluminescent intermediate is generated following action of an enzyme(indicator label) on substrate

• the intensity of the chemiluminescent is measured in a luminometer

• alkaline phosphatase can be used as indicator label and a phosphate ester of admantyl dioxetane is used as substrate

• it has a high sensitivity because it can detect low concentrations of certain analytes

• None of the above