1Which of the following is characteristic of variable domains of immunoglobulins?
- D. They are found only on heavy chains.
- B. They represent the complement-binding site
- A. They occur on both the heavy and light chains.
- C. They are at the carboxy-terminal ends of the molecules.
2Which option characterizes the secondary immune response (select the best answer)?
- G. There is a large increase in IgG but not IgM.
- F. There is an increase in IgM only.
- H. The lag phase is the same as in the primary response.
- E. Equal amounts of IgM and IgG are produced.
3Laboratory results belonging to a 3-year-old patient showed
the following: normal CD4+ T-cell count, normal CD19+ Bcell count, low CD8+ T-cell count.
Which aspect of immunity would be affected?
- B. Formation of plasma cells
- A. Production of antibody
- D. Downregulation of the immune response
- C. Elimination of virally infected cells
4How do cytotoxic T cells kill target cells?
- H. They produce granzymes that stimulate apoptosis
- E. They produce antibodies that bind to the cell.
- F. They engulf the cell by phagocytosis.
- G. They stop protein synthesis in the target cell.
5The CH50 test detects / measures which of the following?
- B. Function of both the classical and alternative pathways
- A. The amount of patient’s serum required to lyse 50% of sensitized sheep RBCs
- D. Function of the lectin pathway only
- C. Genetic deficiencies of any of the complement components
6All of the following are true regarding recognition unit except:
- G. binding occurs at the Fc region of antibody molecules.
- E. it consists of C1q, C1r, and C1s.
- F. the subunits require calcium for binding together.
- H. C1q becomes an active esterase.
7Case study:
A 3-year-old child has a history of serious infections and is currently hospitalized with meningitis. The doctor suspects that he may have a complement deficiency and orders testing. The following results are obtained: decreased CH50, decreased AH50, and normal C4 and C3 levels.
Questions
a. What do the results indicate about the possible pathway(s) affected?
b. Which component(s) are likely to be lacking?
c. What follow-up testing would be recommended?
8Jahan Abdi, a newly-hired highly enthusiastic CLS but a bit clumsy, just dropped the patient’s blood tube while trying to start the CH50 test……… boom! Sample gone! But he was lucky, hematology lab had the EDTA tube which he could immediately run the test with. Happy that he managed the
situation and finished the test, without further thinking he released the result which was an extremely low CH50. Later, he received a call from the physician that result did not have any correlation with patient’s condition. What went wrong?
The EDTA tube used contains EDTA which binds to the calcium in the blood. The complement system uses calcium, so the EDTA tube would have lower calcium than normal, which would give the low CH50 result.
9If the results of serum protein electrophoresis show a significant decrease in the gamma band, which of the following is a likely possibility?
- d. Monoclonal gammopathy
- c. Immunodeficiency disorder
- a. Normal response to active infection
- b. Multiple myeloma
10Which of the following best describes the TCR for antigen?
- b. It is the same for all T cells
- c. It is present in the DN stage.
- a. It consists of IgM and IgD molecules.
- d. α and β chains are unique for each antigen.