Immunodiagnosis (complete)

Question 1

Describe the procedure used in serum protein electrophoresis. What are the underlaying principles?

Answer 1

• Serum (urine, CSF) is placed on a gel
• Turn on voltage
• Measure peaks of albumin, alpha1, alpha2, beta, and gamma

Question 2

What does no gamma peak indicate in an electrophoresis?

Answer 2

Agammaglobulinemia

• No IgG

Question 3

What does a high, broad gamma peak indicate in an electrophoresis?

Answer 3

Polyclonal hypergammaglobulinemia

or severe pyogenic (pus-producing) infections

Question 4

What does a high, single gamma peak indicate in an electrophoresis?

Answer 4

Monoclonal hypergammaglobulinemia

Question 5

What does a normal serum protein electrophoretic pattern look like?

Answer 5

• Large albumin peak
• Baby peaks for alpha1&2, beta, gamma

Go google it NOW!

Question 6

What does a serum protein electrophoretic pattern look like for a person with selective IgA deficiency?

Answer 6

Same as a normal peak

You can’t pick up this deficiency with serum electrophoresis

Question 7

What does a serum protein electrophoretic pattern look like for a person with multiple myeloma?

Answer 7

Large spike in gamma region (AKA M spike) — remember the M protein in MM?

Not as sharp as the monoclonal hypergammaglobulinemia

Question 8

What is single radial immunodiffusion?

Answer 8

Measures individual immunoglobulin (sub)classes — or just Ag

Question 9

What are the types of Ag that can be quantified in single radial immunodiffusion?

Answer 9

Multivalent Ag

• Can form a precipitate w/ an appropriate Ab

Question 10

How is the quantization done in single radial immunodiffusion?

Answer 10

You compare patient’s serum to the controls

Question 11

What are the advantages of passive agglutination over precipitation?

Answer 11

A lot quicker and more sensitive

Question 12

Describe passive agglutination test

Answer 12

• Couple small Ags to RBCs or latex beads
• Add dilutions of pt serum
• Look for agglutination

The agglutination titer is the reciprocal of the highest dilution that produces agglutination

Question 13

What is the difference between direct and indirect immunofluorescence techniques?

Answer 13

Direct:
pt swab smeared on slide, fluorescent-labelled Abs added — a test for ANTIGEN

Indirect:
Known bacteria on slide, add pt’s serum, wash and added fluorescent-labelled anti-human Ig — a test for ANTIBODY

Question 14

Describe the reactions involved when the ELISA is used to measure Ag

Answer 14

Enzyme-linked immunosorbent assay

• works well if Ag is at least divalent
• Need 2 monoAbs
• Put one on the bottom => add pt’s serum
• Wash, then add 2nd monoAb (will stick to other epitope)
• 2nd Ab has enzyme coupled to it (peroxidase)
• Add colorless peroxidase substate => produces color if peroxidase bound to 2nd Ab

Question 15

Describe the reactions involved when the ELISA is used to measure Ab

Answer 15

• Ag is at bottom of plate, sticks there
• Put on pt’s serum
• Wash everything that doesn’t stick
• Add anti-Ab Ig (has enzyme on the end)
• Add enzyme substrate => produces color if testing Ab is present

Question 16

Describe a test which can be used to evaluate T cell immunocompetence in a clinic or on the ward

Answer 16

Think of a TB test

1) Ag is endocytosed by DCs
2) Ag digested w/in endosomes by lysosomal enzymes
3) Ag loaded onto MHC Class II
4) MHC Class II cycles to the DCs surface
5) Th1 anti-TB cells come by
6) Th1 anti-TB cells recognize Ag + MHC Class II.
7) Th1 cells are activated and secrete IFNγ
8) Macrophages are attracted
9) Macrophages are activated and become M1

Question 17

What are tests used to evaluate T cell numbers and function in the lab?

Answer 17

You can stain for CD3, CD4, or CD8 in serum

Question 18

Describe flow cytometry

Answer 18

• Light scattered according to CD markers
• Increasing intensity of CD8 on y-axis
• Increasing intensity of CD4 on x-axis

Question 19

Where would you find both CD4 and CD8 cells?

Answer 19

Only the thymus

• This is where double positives are weeded out

Question 20

Where would you find cells without CD4 or CD8 markers?

Answer 20

Lymph nodes

• Primarily B cells
• These have no CD4 or 8 markers