Question

28. All of the following would be considered good quality control protocols except: a. storing reagents properly b. allowing the reaction to go as long as possible. c. checking temperatures of water baths, etc. d. running positive and negative controls. 29. What would best characterize an indirect immunofluorescent assay when testing for the presence of a specific antibody in the patient's specimen. a. The anti-human immunoglobulin has a fluorescent label. b. The patient's serum is tagged with an enzyme and fluorescent label. c. Antibody conjugated with a fluorescent tag is added directly to unknown antigen fixed to a microscopic slide. 30. In clinical laboratories, chemiluminescence has been used as means of measuring an Ag-Ab complex. Molecules capable of chemiluminescence such as luminol are oxidized by ie (H2O2). The excited molecule returns to its original state and emits energy in the form of light.(Tor F) 31. The traditional test that has been used to determine whether treponemes have invaded the CSF in syphilis has been: a. VDRL b. RPR c. Chemiluminescent assay d. FTA-ABS 32. The affinity of an antibody is the initial attraction of a single Fab site on an antibody with the single epitope present on the corresponding antigen. (Tor)

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Answer 1

Q.28. Answer- b. Allowing the reaction to go as long as possible

Explanation- allowing the reaction to go as long as possible is not good quality control protocol because reactions should be carried out at its optimum time period that will give good results.

Q.29. Answer- a. The anti-human immunoglobulin has fluorescent label

Explanation- in indirect immunofluorescent assay antigen is fixed to microtitre plate and primary antibody is added firstly. This primary antibody if binds to Ag then secondary antibody (anti- human immunoglobulin) is added which is labeled with fluorescent dye. In this technique secondary antibody s added after primary antibody so that it is known as indirect immunofluorescent assay.

Q.30. Answer- True

Explanation- In clinical laboratories, chemiluminescence is used to measure Ag-Ab complex as this is very sensitive method. Luminol is chemuluminescence that is oxidized by H2O2. Luminol is converted into dianion after oxidation and this dianion reacts with O2 and produces triplet dianion which is excited state. This triplet dianion is then comes to ground state dianion by emitting excess energy in the form of photon ( light).

Q.31. Answer- a. VDRL

Explanation- when trepanemes are invaded in CSF in syphilis then cerebrospinal fluid of patient is removed as sample for test. The traditional test for detection of involvement of central nervous system, venereal disease research laboratory test (VDRL) is used. In VDRL, antibodies against syphilis produced by patient reacts with diphosphatidyl glycerol .