Garlanda 3

Question 1

precipitation tests results are understood by

Answer 1

• used formation of immune complexes (antigen-antibody)

- measures level of antigen/antibody by degree of visible precipitation of immune complexes in a gel/solution

Question 2

when do we most often use precipitation tests

Answer 2

suspected fungal infection or pyogenic meningitis (note that that a positive result needs a large amount of antibody or antigen, bc sensitivity is low so a large amount of antigen/antibody is needed for a pos result)

Question 3

what is immunodiffusion?

What 3 zones are present on the petri dish?

Answer 3

A type of precipitation test that measures the amount of antibody antigen complexes formed when diffused through a gel/medium in a petri dish
- has 3 zones: zone of antigen excess, zone of optimal precipitation, zone of antibody excess

Question 4

turbidimetric test

Answer 4

measures light passing through a solution

Question 5

nephelometry test

Answer 5

measures light reflected from a solution

Question 6

agglutination tests

Answer 6

use the cross linking of antibodies with particulate antigens

Question 7

agglutination definition

Answer 7

clumping of insoluble particles

Question 8

precipitation definition

Answer 8

clumping of soluble molecules

Note that antibodies can bind to 2 or more antigens

Question 9

neutralisation tests

Answer 9

a mixture of virus and serum is added to cell culture, the absence of cytopathic effect indicates presence of antibodies against the virus in the serum

Question 10

viral hemagglutination inhibition test

Answer 10

is for viruses that are not cytopathic. Used for influenza, measles, and mumps

Question 11

complement fixation test

Answer 11

is based on generation of MAC during complement activation (antibodies need complement to bind). They are used to detect the presence of specific antibodies. Not used much; maybe for coccidiodomycosis

Question 12

ELISA

Answer 12

• antigen is attached to well in plate
• protein like gelatin is added to block the uncoated surface
• pt serum is added, and they bind
• enyzme linked anti-abs is added
• enzymes substrate is added, and the reaction produces a visible color change

Question 13

ELISA is for which viruses

Answer 13

HIV, HEPA, HEPB

Question 14

western blot has good sensitive but is highly specific

Answer 14

so it is used to confirm a positive result obtained with a screening test

Question 15

How do you get the measurement of titre

Answer 15

the reciprocal of the most diluted solution yielding agglutination

Question 16

What is line immunoassay

Answer 16

A modification of the Western blot;

its where antigens are absorbed into a nylon strip

Question 17

What is RIBA immunoblot

Answer 17

A modification of the Western blot;

it uses synthetic/recombinant antigens

Question 18

T/F immunochromatographic assays can rapidly screen specimens for specific microbial antigens or pt antibodies

Answer 18

T

Note that this is a modification of a western blot

Question 19

Point of care testing includes which tests

Answer 19

• Immunofiltration assay: Rapid elisa where antigens are bound to membrane filters not plates
• Immunochromatographic assays: Antigen solution flows through a porous strip and encounters
  labeled antibody
  – Visible line produced when antigen-antibody immune complexes
  encounter antibody against them
  – Used in pregnancy testing and for rapid identification of some
  infections: group A Streptococcus, Respiratory Syncytial Virus
  (RSV), influenza viruses.

Question 20

Define serology

Answer 20

the determination of the presence of specific antigens or antibodies in blood serum

Question 21

antigen antibody complexes are also called

Answer 21

Immune complexes

Question 22

types of serological tests

Answer 22

• Precipitation tests (immunodiffusion)
• Agglutination tests (latex agglutination)
• Neutralisation tests (virus neutralisation with cytopathic effect; viral hemagglutination inhibition test)
• Complement fixation test (for antibodies)
• Labeled antibody test (ELISA; ab-sandwich ELISA; Immunoblots, Western blot)

Question 23

T/F precipitation will occur no matter the ratio of antigen to antibody present

Answer 23

false, too much antibody or too little will result in suboptimal percipitates

Question 24

both turbidimetry and nephelometry measure?

Answer 24

cloudiness of a solution; They can be used to quantify the amounts of proteins in serum

Question 25

Explain agglutination test

Answer 25

a particle (latex bead/bacterium) is coupled to a reagent antigen or abs. The resulting complex is mixed with pt specimen. If the target ab or antigen is present then it cross links the particles and produces measurable agglutination
VISIBLE CLUMPS ARE FORMED

Question 26

T/F complement fixation tests are more sensitive than agglutination tests

Answer 26

T

Question 27

Adv of ELSIA

Answer 27

• can detect either antigen or ab
• sensitive
• can quantify amounts of antigen or antibody
• easy, quick
• inexpensive, automatic ish
• plates coated with antigen can be stored and used later

Question 28

What markers assess inflammation

Answer 28

ESR
CRP
Procalcitonin
Fibrinogen, haptoglobin, APR

Question 29

ESR depends on

Answer 29

• pro sedimentation factors (fibrinogen, alpha, beta, gammaglobulins)
• negative charge of RBC’s (aka zeta potential)

Question 30

rouleux are

Answer 30

stacks of RBC that settle faster in ESR

Question 31

When is ESR increased

Answer 31

inflammation
pregnancy
anemia
autoimmune disorders (such as rheumatoid arthritis and lupus)
infections
some kidney diseases
some cancers (such as lymphoma and multiple myeloma).

Question 32

ESR:
polycythemia
hyperviscosity
sickle cell anemia
leukemia
low plasma protein (due to liver or kidney disease)
congestive heart failure.

Answer 32

decreased

Question 33

C-reactive protein was the first pattern recognition receptor (PRR) to be identified.
It was named because it reacts with the C polysaccharide of Streptococcus
pneumoniae,

Answer 33

Its binds to lysophosphatidylcholine
expressed on the surface of dead or dying
cells (and some types of bacteria) and
activates the complement system via C1q,
promoting phagocytosis by macrophages,
which clears necrotic and apoptotic cells
and bacteria.

Question 34

T/F CRP Plasma levels begin increasing within 4-6 hours
following an acute inflammatory stimulus and
the half-life of CRP is 5-7 hours, therefore the level
of CRP in the blood is regulated solely by its own
synthesis.
• In healthy adults, CRP concentrations varies
between 0.8 mg/L to 3.0 mg/L.
• CRP levels can rise to more than 500 mg/L
and peak at 48 hours.

Answer 34

T
CRP production increases with rheumatic and
other inflammatory diseases, infection, trauma,
necrosis, malignancy, and allergic reaction.
CRP levels:
-metabolic inflammation (e.g. atherosclerosis and
Type II diabetes mellitus): 2 to 10 mg/L
-mild inflammation and viral infections:10–40 mg/L
-active inflammation, bacterial infection: 40–200
mg/L
-severe bacterial infections and burns: >200 mg/L.
Once inflammation subsides, CRP level falls
quickly because of its short half-life (4 to 7 hours)

Question 35

Procalcitonin

Answer 35

Peptide precursor of calcitonin. Generated by cleavage
of preprocalcitonin by endopeptidase.
116 amino acids, produced by parafollicular cells (C cells) of the thyroid and by
the neuroendocrine cells of the lung and the intestine.
Normal is (0.01 µg/L), rises
in a response to a
proinflammatory
stimulus, especially of
bacterial origin: acute
phase reactant,
Bacterial infections induce a universal
increase in the CALC-1 gene expression.
CALC-1 is not significantly induced by viral or
non-infectious inflammations.
In severe infections, blood levels of procalcitonin
may rise form 0.01 µg/L to 100 µg/L.
In serum, procalcitonin has a half-life of 25 to
30 hours.
The FDA first cleared the procalcitonin test to help
guide treatment for lower respiratory infections, such
as acute bronchitis, pneumonia, and acute forms of
chronic obstructive pulmonary disease (COPD). The
major causes of these infections are viruses rather than
bacteria, and treatment with antibiotics is not effective.
This can help reduce the unnecessary use of antibiotics.