Immunology and Serology Lec

d

Which branch of science specifically focuses on the in vitro laboratory detection and measurement of antigen-antibody reactions?
a = Cytology
b = Histology
c = Hematology
d = Serology
e = Immunology

b

Immunology is broadly defined as the study of:
a = Blood cell counts and hemoglobin structure
b = The immune system, including cellular and molecular defense mechanisms
c = Tissue biopsy preparations and cellular pathology
d = Bacterial culture and antibiotic susceptibility
e = Chemical compounds present in human serum

e

Which immunoglobulin class is the first to be produced in a primary immune response and serves as a marker for active, acute infection?
a = IgA
b = IgD
c = IgE
d = IgG
e = IgM

c

Presence of IgG antibodies against a specific pathogen in a patient's serum typically indicates:
a = An immediate anaphylactic hypersensitivity reaction
b = Active acute stage of primary infection
c = Past infection or acquired immunity
d = Invalid laboratory assay performance
e = Severe immunodeficiency state

c

In Dengue fever diagnostics, which viral marker is most reliable for detection during the acute phase (Days 1 to 7)?
a = IgG antibody
b = IgM antibody
c = NS1 antigen
d = Core capsid antibody
e = Envelope protein IgG

c

How many major serotypes of Dengue virus are recognized in routine clinical diagnostics?
a = 2
b = 3
c = 4
d = 5
e = 6

c

What is the primary specimen of choice for the majority of routine serological testing?
a = EDTA whole blood
b = Heparinized plasma
c = Serum
d = Synovial fluid
e = Saliva

b

If serological testing cannot be performed immediately but will be completed within 72 hours, how should the serum specimen be stored?
a = At room temperature (20–25°C)
b = Refrigerated at 2°C to 8°C
c = Deep frozen at -70°C
d = Incubated at 37°C
e = Kept in a dark desiccator

b

If serological testing must be delayed for longer than 72 hours, what is the appropriate storage protocol?
a = Store at 2°C to 8°C
b = Freeze at -20°C or colder
c = Leave at room temperature with preservative
d = Incubate at 56°C
e = Store in a formalin container

b

Prior to performing serological testing, why must the specimen be inspected to ensure no red blood cells or hemolysis are present?
a = Hemolysis increases the volume of the sample artificially
b = Intracellular RBC components can cause interference and false-negative or invalid results
c = Hemolyzed serum prevents liquid pipetting
d = Hemolysis converts IgM antibodies into IgG
e = RBCs absorb all the diluent in the assay

b

Which group of plasma proteins functions to assist antibodies in lysing cell membranes, promoting opsonization, and mediating inflammation?
a = Immunoglobulins
b = Complement system
c = Acute phase reactants
d = Cytokines
e = Fibrinogen factors

d

Which complement complex forms the Membrane Attack Complex (MAC) directly responsible for target cell lysis?
a = C1q, C1r, C1s
b = C2a, C4b, C3b
c = C3a, C4a, C5a
d = C5b - C9
e = C1 - C4

b

Which complement fragment acts as a primary opsonin, coating microbial targets for enhanced phagocytosis?
a = C3a
b = C3b
c = C5a
d = C5b
e = C9

c

What is the primary function of complement fragment C5a during an immune response?
a = Direct membrane pore formation
b = Neutralization of viral toxins
c = Powerful chemotaxis and leukocyte recruitment
d = Inactivation of serum antibodies
e = Inhibition of B-cell proliferation

b

Standard heat inactivation of serum complement requires heating the sample in a water bath at:
a = 37°C for 30 minutes
b = 56°C for 30 minutes
c = 56°C for 15 minutes
d = 100°C for 5 minutes
e = 72°C for 15 minutes

a

If heat-inactivated serum sits at room temperature for more than 4 hours before testing, how should it be re-inactivated?
a = Heated at 56°C for an additional 10 minutes
b = Heated at 56°C for another full 30 minutes
c = Heated at 100°C for 2 minutes
d = Refrigerated for 24 hours
e = Discarded immediately as unusable

b

A 4th-generation HIV combination immunoassay (HIV Ag/Ab assay) is designed to detect which two targets?
a = HIV DNA and RNA
b = p24 viral antigen and HIV-1/HIV-2 antibodies
c = Reverse transcriptase enzyme and CD4 count
d = gp120 antigen and HLA markers
e = p17 protein and IgM antibodies only

b

Which serological marker indicates active or current Hepatitis B infection in a patient?
a = Anti-HBs
b = HBsAg
c = Anti-HBc IgG
d = Anti-HBe
e = Anti-HBs IgM

c

Following successful Hepatitis B vaccination, which antibody titer should be present at protective levels

(Greater than or equal to10 mIU/mL)?
a = Anti-HBc
b = Anti-HBe
c = Anti-HBs
d = HBsAg
e = HBeAg

a

Which Hepatitis B marker is the most specific indicator of acute or recent Hepatitis B virus infection?
a = Anti-HBc IgM
b = Anti-HBc IgG
c = Anti-HBs
d = HBeAg
e = Anti-HBe

b

What hormone is measured in urine or serum to perform a routine laboratory pregnancy test?
a = Human placental lactogen (hPL)
b = Human chorionic gonadotropin (hCG)
c = Luteinizing hormone (LH)
d = Progesterone
e = Estriol

c

Which of the following is classified as a non-treponemal screening test for Syphilis?
a = FTA-ABS
b = TPPA
c = RPR
d = TPHA
e = MHA-TP

c

Which of the following syphilis diagnostic assays is classified as a specific treponemal confirmatory test?
a = VDRL
b = RPR
c = FTA-ABS
d = TRUST
e = USR

b

Infectious Mononucleosis is commonly diagnosed by detecting which type of antibodies in patient serum?
a = Autoimmune antinuclear antibodies
b = Heterophile antibodies
c = Cold agglutinins
d = Neutralizing IgA antibodies
e = Anti-CCP antibodies

b

The clinical introduction of monoclonal antibody (MAb) technology revolutionized serological testing primarily because MAbs provide:
a = Indefinite specimen shelf-life
b = High specificity, sensitivity, rapid results, and automation suitability
c = Elimination of the need for pipetting
d = Conversion of all assays into manual tube agglutinates
e = Universal binding to any biological target

d

Which immune cells are directly responsible for the production and secretion of antibodies?
a = T helper cells
b = Cytotoxic T lymphocytes
c = Natural Killer (NK) cells
d = B cells (Plasma cells)
e = Neutrophils

c

Which collection tube is standard for obtaining serum specimens in serology?
a = Lavender top (EDTA)
b = Light blue top (Sodium Citrate)
c = Plain red top or Serum Separator Tube (SST)
d = Green top (Heparin)
e = Gray top (Sodium Fluoride)

e

Which of the following non-serum body fluids can be evaluated using specialized immunological assays?
a = Cerebrospinal fluid (CSF)
b = Synovial fluid
c = Pleural and peritoneal fluid
d = Urine and saliva
e = All of the above

b

Why is active complement heat-inactivated before running specific agglutination assays?
a = Complement converts soluble antigens into insoluble precipitates
b = Complement can lyse indicator RBCs and cause false-negative reactions
c = Complement destroys all immunoglobulins in the sample
d = Complement thickens serum and prevents serial dilutions
e = Heat inactivation causes antibodies to bind permanently

b

Complement activation leads to increased blood flow, vasodilation, and leukocyte recruitment. This overall process is known as:
a = Hemostasis
b = Inflammation
c = Neutralization
d = Fibrinolysis
e = Agglutination

c

What is the primary function of a micropipettor in the immunology and serology laboratory?
a = Centrifugation of small blood samples
b = Incubation of microplate wells at 37°C
c = Rapid, repetitive, and precise quantitative delivery of micro-volumes
d = Automated heat inactivation of complement
e = Qualitative measurement of antibody titers

b

A dilution is best defined mathematically as an expression of:
a = Absolute mass per unit volume
b = Relative concentration representing sample volume relative to total volume
c = Total solute weight divided by solvent weight
d = Reciprocal of the final chemical mass
e = Number of antibodies present per milliliter

d

If a technician mixes $0.1\text{ mL}$ of serum with $0.9\text{ mL}$ of saline, what is the resulting specimen dilution?
a = 1:2
b = 1:5
c = 1:9
d = 1:10
e = 1:100

d

What is the Dilution Factor (DF) for a sample prepared at a 1:20 dilution?
a = 0.05
b = 2
c = 19
d = 20
e = 200

d

If an assay performed on a 1:5 diluted serum sample yields an antibody titer reading of 50 IU/mL, what is the true concentration in the original undiluted specimen?
a = 10 IU/mL
b = 50 IU/mL
c = 100 IU/mL
d = 250 IU/mL
e = 500IU/mL

b

How is the Dilution Factor (DF) mathematically related to the dilution ratio?
a = DF is the square root of the dilution ratio
b = DF is the reciprocal of the dilution ratio
c = DF is obtained by subtracting sample volume from total volume
d = DF is always equal to 1.0
e = DF is the product of sample volume and diluent volume

d

Which antibody class is capable of crossing the human placenta to provide passive immunity to the fetus?
a = IgA
b = IgD
c = IgE
d = IgG
e = IgM

b

Dengue virus IgM antibodies typically begin to appear in patient circulation around which day after fever onset?
a = Day 1
b = Day 3 to 5
c = Day 14 to 21
d = Day 30
e = Day 60

b

Repeated freezing and thawing of serum specimens should be strictly avoided because it causes:
a = Conversion of serum into plasma
b = Denaturation of proteins and degradation of antibody activity
c = Inactivation of sodium preservative
d = Rapid multiplication of RBCs
e = Evaporation of diluent

c

Which anaphylatoxin fragments generated during complement activation promote histamine release from mast cells?
a = C1q and C1r
b = C2b and C4b
c = C3a, C4a, and C5a
d = C6 and C7
e = C8 and C9

b

In a 1:50 dilution, if the total volume prepared is 1.0mL, what is the volume of the serum sample used?
a = 0.01mL
b = 0.02mL
c = 0.05 mL
d = 0.10mL
e = 0.50mL

d

In a 1:50 dilution with a total volume of $1.0\text{ mL}$, what volume of diluent (saline) is required?
a = 0.50mL
b = 0.90mL
c = 0.95mL
d = 0.98mL
e = 0.99mL

a

Which immunologic reagent utilizes known antibodies to identify unknown cellular or microbial antigens in a specimen?
a = Direct/Indirect Antisera
b = Diluent saline
c = Complement buffer
d = Patient serum
e = Heterophile sheep red cells

c

What type of immunity is conferred by Hepatitis B vaccination?
a = Natural active immunity
b = Natural passive immunity
c = Artificial active immunity
d = Artificial passive immunity
e = Innate non-specific immunity

b

What type of protection is provided by administering Hepatitis B Immune Globulin (HBIG)?
a = Artificial active immunity
b = Artificial passive immunity
c = Natural active immunity
d = Natural passive immunity
e = Cell-mediated cytotoxicity

b

Which non-treponemal syphilis test uses microscopic evaluation to observe antigen-antibody flocculation?
a = RPR
b = VDRL
c = FTA-ABS
d = TPHA
e = ELISA

b

Why does the Rapid Plasma Reagin (RPR) test allow macroscopic (visual without microscope) reading?
a = It uses fluorescent dye
b = It incorporates charcoal particles into the antigen complex
c = It uses gold nanoparticles
d = It utilizes radioactive isotopes
e = It causes red cell hemolysis

c

Presence of both HBsAg and Anti-HBc IgM in a patient's serologic profile confirms:
a = Recovery phase from past Hepatitis B infection
b = Successful Hepatitis B vaccination
c = Acute Hepatitis B infection
d = Chronic Hepatitis B carrier state without viral activity
e = Natural immunity to Hepatitis A

c

If a patient tests negative for HBsAg but positive for Anti-HBs and negative for Anti-HBc, what is their clinical status?
a = Acute Hepatitis B infection
b = Chronic active Hepatitis B infection
c = Immune due to Hepatitis B vaccination
d = Immune due to natural past infection
e = Non-immune susceptible individual

a

If a patient tests negative for HBsAg, positive for Anti-HBs, and positive for Anti-HBc Total, what is their clinical status?
a = Immune due to past natural infection
b = Immune due to Hepatitis B vaccination only
c = Acute infection window period
d = Chronic carrier state
e = False-positive assay result

a

Which complement pathway is directly triggered by antigen-antibody complexes (IgM or IgG)?
a = Classical pathway
b = Alternative pathway
c = Lectin pathway
d = Properdin pathway
e = Scavenger pathway

c

If a tube contains $0.2\text{ mL}$ of serum and $0.6\text{ mL}$ of saline diluent, what is the dilution of serum in this tube?
a = 1:2
b = 1:3
c = 1:4
d = 1:5
e = 1:8

c

In a serial 1:2 dilution tube series (Tubes 1 to 4), where Tube 1 is a 1:2 dilution, what is the final dilution in Tube 4?
a = 1:4
b = 1:8
c = 1:16
d = 1:32
e = 1:64

c

Which term refers to the process where antibodies or complement coat pathogens to facilitate recognition and ingestion by phagocytes?
a = Agglutination
b = Chemotaxis
c = Opsonization
d = Neutralization
e = Precipitation

b

Which statement regarding IgM antibody structure is correct?
a = It exists primarily as a monomer in serum
b = It exists as a pentamer with 10 potential antigen-binding sites
c = It is the predominant antibody found in mucosal secretions
d = It mediates Type I immediate allergic hypersensitivity
e = It crosses the placental barrier during the 3rd trimester

a

Which antibody monomer is the primary secretory immunoglobulin found in body fluids such as tears, saliva, and colostrum?
a = IgA
b = IgD
c = IgE
d = IgG
e = IgM

c

Which class of immunoglobulin is involved in allergic reactions and defense against parasitic helminth infections?
a = IgA
b = IgD
c = IgE
d = IgG
e = IgM

b

The presence of icteric or lipemic serum can interfere with serological tests primarily by interfering with:
a = Chemical decomposition of antibodies
b = Spectrophotometric or optical detection methods
c = Automatic heating of complement
d = Antibody synthesis in vitro
e = Specimen centrifugation speeds

c

If a serum specimen is diluted 1:10 and analyzed for an antigen, yielding a measured value of 15 ng/mL, what concentration should be reported for the patient sample?
a = 1.5ng/mL
b = 15 ng/mL
c = 150 ng/mL
d = 1500ng/mL
e = 0.15 ng/mL

b

What is the primary reason for centrifuging a blood specimen after complete clotting when preparing serum for serology?
a = To break open RBCs and release hemoglobin
b = To separate the cell free fluid (serum) from the insoluble blood clot
c = To heat-inactivate complement proteins
d = To dissolve fibrinogen into fibrin
e = To destroy bacterial contaminants