09.11.18 Immune Assays

Question 1

What are initial screening labs to consider for chronic immune defects?

Answer 1

• CBC with diff
• Inflammatory markers
• Chemistry panel

Question 2

How would you evaluate antibody deficiency/defects?

Answer 2

Measure total serum IgG, IgA, and IgM and check for normal range

• Pattern of abnormality
• Measure subclasses
• Normal quantity doesn’t = normal function

Question 3

When would you check serum IgD?

Answer 3

Periodic fever

Question 4

What are assays for antibody function?

Answer 4

Antibody titers to specific pathogens (titers to vaccine- diphtheria/tetanus)

Question 5

antibodies generated in response to polysaccharides of gut flora which cross-react with A or B blood group erythrocyte antigens

Answer 5

Isohemagglutinins

Question 6

How can you measure antibody response to polysaccharides?

Answer 6

Pneumococcal titers in older children given the polysaccharide vaccine

Question 7

What is used to quantitate lymphocytes?

Answer 7

Flow cytometry

Question 8

How does flow cytometry work?

Answer 8

• Tag antibody, look for immunofluorescence, and quantify it

Question 9

What cell type is CD3?

Answer 9

T cells

Question 10

What cell type is CD4?

Answer 10

Helper T cells

Question 11

What cell type is CD8?

Answer 11

Cytotoxic T cells

Question 12

What cell type is CD19?

Answer 12

B cells

Question 13

What cell type is CD 16/56?

Answer 13

NK cells

Question 14

• Detection of fetal cells in maternal circulation
• Used to monitor intrauterine transfusion
• Intracellular stain with fetal Hb specific monoclonal antibody

Answer 14

Fetal Hemoglobin Testing

Question 15

How can you test for T cell function?

Answer 15

Mitogen test

-Mitogens- compounds that cause proliferation in T cells

Question 16

How does a mitogen test work?

Answer 16

1. Incubate patients lymphocytes with mitogen
2. Add thymidine that will be incorporated into proliferating T cell DNA
3. See how much label was incorporated and compare with control

Question 17

• Classic in vivo test of cellular immunity
• Inject antigen which you have already been exposed to
• Positive response will require immune response

Answer 17

Cutaneous Delayed-Type Hypersensitivity (DTH)

Question 18

What is an example of a delayed type hypersensitivity test?

Answer 18

PPD

Question 19

How would you test for neutrophil defects?

Answer 19

First- CBC with diff

If normal numbers order tests for function (Varies with defect- Ex. neutrophil oxidative burst/NBT; Serum IgE; azurophilic granules in granulocytes)

Question 20

How would you test for complement defect?

Answer 20

1. Total hemolytic complement (CH50)

If normal and complement defect still suspected do AH50

Question 21

What does CH50 assess?

Answer 21

Classical pathway

Question 22

What does AH50 assess?

Answer 22

Alternative complement deficiencies