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serology > Practicum > Flashcards

Practicum Flashcards

1
Q

List the principle and/or clinical significance of direct fluorescent antibody test with reagents & reactions.

A

A known Ab combined with fluorescent tag is added to unknown Ag that is fixed to a slide. After incubation & wash, the slide is read using a fluorescent scope. If Ab reacts with Ag it will show bright green or orange-yellow on a dark background.

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2
Q

List the principle and/or clinical significance of ELISA with reagents & reactions.

A

Competitive: enzyme-labeled Ag competes w/ unlabeled pt Ag for binding sites on Ab molecules attached to a solid phase. The more pt Ag is bound, the less enzyme-labeled Ag can attach.
Non-competitive: higher sensitivity; measures status of immunity to certain agents and for autoantibody testing. Either Ag or Ab is bound to solid phase. When Ag is used for coating, pt Ab is added and given time to react. After a wash, enzyme-labeled Ab is added. This 2nd Ab reacts w/ any pt Ab bound to the solid phase. If no pt Ab is bound, the 2nd Ab will not bind. After another wash, enzyme substrate is added. Color development is directly proportional to the amount of pt Ab.

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3
Q

List the principle and/or clinical significance of complement fixation test with reagents & reactions.

A

Complement is used as a reagent. Comp. fixation occurs after the binding of Ag & Ab so complement uptake is an indicator of the presence of either specific Ag or Ab. Detects viral, fungal or rickettsial Abs. Test uses an Ag & Ab, one of which is unknown, and sheep RBCs coated w/ hemolysin which will lyse in presence of complement. If lysis occurs in Stage 2, complement did not fix during Stage 1

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4
Q

List the principle and/or clinical significance of RPR with reagents & reactions.

A

Flocculation test for syphilis. Based on cardiolipin Ag technique but read macroscopically. Performed on unheated pt serum or plasma (does not require inactivation of plasma/serum) w/modified VDRL Ag and charcoal particles. Choline chloride replaces heat to inactivate complement.

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5
Q

List the principle and/or clinical significance of FTA-ABS with reagents & reactions.

A

Treponemal test specific for syphilis. Pt serum is absorbed with extract of nonpathogenic Reiter treponeme to remove nonspecific treponomel ab. A virulent Nichols strain of T pallidum (ag) is allowed to react with pt serum (ab). Specific T pallidum attached to the Nichols strain on a slide demonstrates with fluorescen-labeled antiglobulin using dark field fluorescent microscopy.

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6
Q

List the principle and/or clinical significance of Davidson test (differential adsorption) with reagents & reactions.

A

Determination of the anti-sheep antibodies after absorption with guinea pig kidney and possibly beef RBCs. A positive reaction is indicated by complete removal of anti-sheep agglutinins (Ab) by guinea pig kidney and/or beef RBCs.

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7
Q

List the principle and/or clinical significance of RA test with reagents & reactions.

A

Screen: Rheumatoid factor (RF) Ab is found in ~80% of pt’s. Uses agglutination test with latex particles coated with IgG.
Diagnostic: EIA technique or Nephelometric assays used to test for IgG or IgA isotypes which rarely occur in other diseases.
Disease activity is followed by measuring inflammation thru ESR, CRP & complement components.

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8
Q

List the principle and/or clinical significance of ANA test with reagents & reactions.

A

Screen: Fluorescent Antinuclear Ab (FANA); Mouse kidney or human epithelial HEp-2 cells are fixed to a slide and allowed to react with pt serum. Fluorescent-tagged antihuman immunoglobulin or horseradish peroxidase is added.
Diagnostic: Double-stranded DNA Ab are seen only in lupus (50-70% of cases) and levels correlate with disease activity. Produces a peripheral or homogenous staining pattern on indirect immunofluorescence.

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9
Q

List the principle and/or clinical significance of cold agglutinins with reagents & reactions.

A

Keep blood sample at 37C until serum & cells separate. Make serial dilutions of sample serum with human group O as the Ag. Incubate overnight in fridge & view for agglutination. Warm to 37C for 30 mins. If agg. disperses upon warming, there are cold agglutinins present. If agg. doesn’t disperse, no cold agglutinins are present. High titers that do not vary over time may indicate mycoplasma pneumonia, IM, autoimmune hemolytic anemia, and viral infections (mumps, rubella, flu, HIV, etc).

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10
Q

What is the causative agent of syphilis? of Infectious mononucleosis?

A

Syphilis: Treponema pallidum
IM: Epstein-Barr virus (herpes)

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11
Q 
Identify the class of immunoglobulins that:
are produced 1st after exposure to Ag
A

IgM

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12
Q 
Identify the class of immunoglobulins that:
found in greatest concentration
A

IgG

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13
Q 
Identify the class of immunoglobulins that:
in greatest concentration after 2nd Ag exposure
A

IgG

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14
Q 
Identify the class of immunoglobulins that:
associated with allergic reactions
A

IgE

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15
Q

Define heterophile antibody

A

Ab that reacts with Ag that is apparently unrelated to the Ag that caused its production (a cross-reacting Ab). They are separated into Forssman and Non-Forssman types. Forssman Ab must be removed from pt serum before serologic testing b/c it causes questionable results. Forssman Ab is removed from serum by absorption with guinea pig kidney. Non-Forssman type Ab are removed with Beef RBCs.

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16
Q

What is the Paul-Bunnell presumptive test?

A

Based on agglutination of 2% sheep RBCs by all heterophile Ab in pt serum. It is positive for IM Ab, Forssman Ab & serum sickness Ab. A positive test would be followed by a Davidson Differential to confirm IM.

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17
Q

What is the Davidson Differential Test?

A

Determines anti-sheep Ab after absorption with Guinea pig kidney and/or Beef RBCs. Specific for IM, but also determines Forssman Ab and Serum Sickness Ab. A positive test is indicated by complete removal of anti-sheep agglutinins (Ab) by guinea pig kidney and/or beef RBCs.

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18
Q

List the differential absorption characteristics of Infectious Mono antibodies

A

Davidson
Absorbed by Guinea pig kidney: No
Absorbed by Beef RBCs: Yes
(Ab specific to IM is Non-Forssman type)

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19
Q

List the differential absorption characteristics of Forssman antibodies

A

Davidson
Absorbed by Guinea pig kidney: Yes
Absorbed by Beef RBCs: No

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20
Q

List the differential absorption characteristics of serum sickness antibodies.

A

Davidson
Absorbed by Guinea pig kidney: Yes
Absorbed by Beef RBCs: Yes

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21
Q

Define reagin

A
  1. Ab formed against lipid material from damaged cells (syphilis)
  2. IgE (allergy response)
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22
Q

Define anamnestic reaction

A

Secondary response to antigen

23
Q

Define prozone and post zone

A

Prozone: failure of serologic rxn to occur due to antibody excess.
Postzone: failure of serologic rxn to occur due to antigen excess.

24
Q

Define flocculation

A

Non-treponemal Ag test. Alcoholic extracts of beef heart tissue (cardiolipin) is mixed with lecithin & cholesterol. The cholesterol absorbs tissue lipids so agglutination particles can be seen. RPR & VDRL most common types.

25
Q

Define cross-reaction

A

When an antigen is so structurally similar to a second antigen that it will react with antibody to the second antigen.

26
Q

Define Fc

A

Fragment of immunoglobulin molecule obtained by papain cleavage that consists of carboxy-terminal halves of 2 heavy chains, held together by disulfide bonds. Activates complement

27
Q

Define Fab

A

Fragment of immunoglobulin molecule obtained by papain cleavage that consists of a light chain and one half of a heavy chain held together by disulfide bonds. Represents one antigen-binding site on the immunoglobulin molecule.

28
Q

Define passive acquired immunity

A

Immunity dependent on injection of preformed antibodies, or acquired in utero, or from mother’s milk. Transient, last only a few weeks or months.

29
Q

Define active acquired immunity

A

Host response to foreign agents that depends on T & B lymphocytes and is characterized by the presence of antibodies that cross-react with heart tissue, specific to antigen and ability to remember prior exposure. Results from natural exposure or vaccination.

30
Q

Define adoptive immunity

A

Passive immunity resulting from immunization of sensitized lymphocytes into a host from an immune donor.

31
Q

Define hinge region

A

The flexible portion of the heavy chain of an immunoglobulin molecule that is located between the first and second constant regions. Allows molecule to bend to let the two antigen-binding sites operate independently

32
Q

Define constant region

A

The carboxy-terminal segment (half of immunoglobulin light chains or three quarters of heavy chains) that consists of a polypeptide sequence found in all chains of that type.

33
Q

Define variable region

A

The amino-terminal region of an immunoglobulin molecule (half of a light chain or quarter of a heavy chain) that has considerable variations in amino acid sequence. Responsible for the specificity of a particular immunoglobulin molecule.

34
Q

Identify the results seen in syphilis serology with a biological false positive

A

(?) Non-treponemal (flocculation)(VDRL, RPR) tests detect Ab in serum that can be caused by agents other than syphilis e.g. malaria, atypical pneumonia, IM, TB, cancer, URI, viral diseases, drug addiction, some vaccinations, etc. [Ppt p.9 in Syphilis]

35
Q

What samples can be used in the RPR and the VDRL

A

RPR: serum or plasma
VDRL: serum or CSF

36
Q

Give the complement cascade, subcomponents and essential elements

A

C1qrs (requires Ca2+).
It cleaves C4 and C2 (requires Mg) to form C3. Then C5, C6, C7, C8, C9 are formed. C9 polymerizes to cause lysis to the target cell.

37
Q

List the immunoglobulin classes that can bind complement

A

IgM (1 molecule needed to activate complement)

IgG (2 molecules needed to activate complement)

38
Q

Differentiate between T and B cells in reference to type of immunity each is responsible for

A

B cells: Humoral Immunity - synthesis & release of Ab into blood & BFs, directly neutralizes Ag.
T cells: Cellular Immunity - production of sensitized lymphocytes & their products (lymphokines).

39
Q

State the titer that indicates immunity to rubella

A

10

40
Q

If an individual is vaccinated for rubella, name the type of immunity

A

Active acquired immunity

41
Q

Describe the special specimen handling for cold agglutinins

A

Keep blood sample at 37C until serum & cells separate.

42
Q

List the correct order of appearance of specific markers (Ab and/or Ag) for Hep B

A
  1. HBs Ag
  2. HBe Ag
  3. IgM anti-HBc
  4. anti-HBe
  5. anti-HBs
43
Q

Evaluate the hepatitis disease status of a patient if given the markers:
HBs Ag

A

HBsAg: Appears 2-12 weeks after exposure to HBV, becomes undetectable by 12-20 weeks in acute Hep B. In chronic, it remains elevated.

44
Q

Evaluate the hepatitis disease status of a patient if given the markers:
HBe Ag

A

HBeAg: appears shortly after HBsAg appears and disappears shortly before the HBsAg also disappears in recovering pt. May stay elevated in chronic pt. Present during active replication so indicates stage of high infectivity. The pt stays infectious until the anti-HBe appears.

45
Q

Evaluate the hepatitis disease status of a patient if given the markers:
IgM anti-HBc

A

IgM anti-HBc: Indicates current or recent acute infection. Appears weeks after HBsAg and stays up to 6 months. Detected between disappearance of HBsAg and appearance of HBs antibodies.

46
Q

Evaluate the hepatitis disease status of a patient if given the markers:
anti-HBe

A

anti-HBe: appears shortly after HBeAg disappears, indicates pt is recovering from acute infection.

47
Q

Evaluate the hepatitis disease status of a patient if given the markers:
anti-HBs

A

anti-HBs: appears during recovery of acute infection, weeks to months after HBsAg disappears.

48
Q

What are modes of transmission for different hepatitis viruses

A

A: fecal-oral (food, water)
B: blood, sexual, needle-sharing, perinatal
C: blood, sexual, needle, transfusions (prior 1989)
D: blood borne, HBV infection req’d first

49
Q

Test most widely used to detect HIV antibody

A

Screen: ELISA
Confirmatory: Western blot

50
Q

How long on average does it take for an individual to develop HIV antibodies after exposure to HIV virus

A

6 weeks

51
Q

What is the RAST used for?

A

Serologic determination of antigen-specific IgE. Uses pt serum instead of skin tests to determine allergies.

52
Q

Multiple myeloma most commonly involves which immunoglobulin class

A

IgG

53
Q

What is the main barrier against foreign particle invasion into the body

A

Skin

54
Q

Define window phase in HIV testing

A

The length of time after infection that it takes for the virus to become detectable by HIV tests. (Varies person to person and by test used, but no more than 3 months after exposure.)

serology (1 decks)

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