Greg - Clinical Immunology (Allergy)

Question 1

What are the clinical areas in the immunology lab?
(3)

Answer 1

Autoimmunity

Primary/secondary immunodeficiency

Allergy

Question 2

What is done in an autoimmunity lab?

Answer 2

Screening for autoantibodies which are indicators for disease

Question 3

Give an example of some antibodies measured in an autoimmunity lab
(5)

Answer 3

Antinuclear antibodies

Anti-neutrophil cytoplasmic antibodies

tTG antibodies

Rheumatoid factor

Anti-cyclic citrullinated peptide antibodies

Question 4

List some methods of detecting antibodies in the autoimmunity lab
(3)

Answer 4

ELISA/immunoassay

Indirect immunofluorescence

Direct immunofluorescence

Question 5

What is done in a primary/secondary immunodeficiency laboratory

Answer 5

Detecting dysfunction in the immune system caused by inherited (primary) or non-inherited (secondary) immunodeficiency

Question 6

What methods are used in an immunodeficiency laboratory?

Answer 6

Flow cytometry
Cell function assays
Complement assays
Serum protein electrophoresis

Question 7

What is carried out in an allergy laboratory?

Answer 7

Detecting allergies against environmental antigens

Question 8

What methods are used in an allergy laboratory?
(3)

Answer 8

Specific IgE

Mast cell tryptase

Basophil activation

Question 9

Why would we need to measure specific antibody responses?

Answer 9

To test for vaccination

To test for allergens

Question 10

Why would we need to test for antinuclear antibodies

Answer 10

To test for lupus

Question 11

What antibodies do we test for in coeliac disease?

Answer 11

Tissue transglutaminate antibodies (tTG antibodies)

Question 12

What antibodies do we test for in lupus?

Answer 12

Antinuclear antibodies

Question 13

What antibodies do we test for in rheumatoid arthritis?

Answer 13

Anti-cyclic citrullinated peptide antibodies

Question 14

What is a primary immunodeficiency and give an example?

Answer 14

An inherited condition you are born with

e.g. X linked agammaglobulinaemia

Question 15

What is a secondary immunodeficiency and give an example?

Answer 15

Immunodeficiency developed in life

e.g. HIV

Question 16

What can we determine in an allergy lab?

Answer 16

Diagnosis and prognosis of an allergy

How severe your allergy will be and what causes the allergy

Question 17

What is an allergy?

Answer 17

An inappropriate immune response to a harmless environmental antigen

Question 18

List the components that are mainly involved in allergy
(5)

Answer 18

Mast cells

T cells

B cells

IgE

Histamine

Question 19

What are the differences between an allergy and an intollerance?

Answer 19

Allergies are rapid onset, reproductible reactions

Intolerances are usually slower in onset and are not life-threatening

Question 20

List the main symptoms of allergies
(6)

Answer 20

Asthma

Eczema

Rhinoconjunctivitis

Urticaria

Vomiting/diarrhoea

Systemic anaphylaxis/Death

Question 21

What test is usually carried out within 6 hours after an allergic reaction?

Answer 21

Test for mast cell tryptase

Which detects products of mast cell degranulation

Question 22

What are the requirements of a type 1 hypersensitivity?
(4)

Answer 22

Requires sensitisation

Multiple genetic factors contribute

Environmental factors contribute

Risk is conferred by many genes including HLA and cytokines

Question 23

What usually happens to IgE after a while?

Answer 23

It degrades

Question 24

What happens to IgE when it binds to mast cells?

Answer 24

IgE doesn’t break down and can remain stable

Question 25

What happens when IgE bound to mast cells become cross linked?

Answer 25

It results in histamine being released (mast cell degranulation) and thus an allergy

Question 26

What are the two mechanisms of diagnosing an allergy?

Answer 26

Measurement of IgE Measurement of mast cell products such as tryptase

Question 27

How is total IgE measured?

Answer 27

By immunoassay via chemiluminescence or fluorescence based means

Question 28

Why is high IgE regarded as non specific? (3)

Answer 28

It doesnt just indicate allergy Indicates parasitic diseases Or conditions such as hyper-IgE syndrome

Question 29

What is a specific IgE test?

Answer 29

Measurement of the level of IgE directed against the suspected allergen

Question 30

What is ELISA?

Answer 30

Enzyme-linked immunosorbent assay A method which utilises the specificity of antibodies to quantify the level of a soluble analyte of interest

Question 31

How is ELISA usually carried out? (2)

Answer 31

Over multi-well plates or tubes (immunocap) A labelled commercially available antibody is used to detect the molecule of interest

Question 32

What are the three different types of reporter molecules?

Answer 32

Colorimetric Chemiluminescence Fluorescence

Question 33

Whats the difference between an indirect and a direct ELISA?

Answer 33

Indirect -> antigen coats well, serum sample added, if antibodies present they bind to antigen, labelled antibody is added, amount of fluorescence is labelled Direct -> labelled antibody binds to antigen

Question 34

How do we use ELISA?

Answer 34

A series of standards with known concentration of antibody come with the bought in labelled antibody are run alongside the unknowns Form standard curve Measure sample against curve

Question 35

How do you detect allergen specific IgE using an immunocap? (7)

Answer 35

Antigen is pre-coated on a 'cap' Diluted patient serum is added and if the specific IgE is present will bind Unbound serum proteins are washed away A fluorescent-labelled secondary anti-IgE is added Unbound secondary antibody is washed away Fluorescence signal is measured Fluorescence is proportional to anti-peanut antibody concentration