Greg - Clinical Immunology (autoimmunity)

Question 1

What is an autoimmune reaction?

Answer 1

A reaction against self

The immune system targeting an autoantigen - self antigen

Question 2

How many known autoimmune diseases are there?

Answer 2

There are 100+ diseases

Question 3

Classify auto immune diseases

Answer 3

Organ-specific

Systemic

Question 4

Give an example of an organ-specific autoimmune disease

Answer 4

Type 1 diabetes

Question 5

Give an example of a systemic autoimmune disease

Answer 5

Systemic lupus erythematosus

Question 6

Why are auto-immune conditions usually life long?

Answer 6

Because the antigen cannot be eradicated, stimulus is constant therefore disease is usually life-long

Question 7

Give two occasions where the immune system must be suppressed?

Answer 7

Pregnancy

Transplant

Question 8

In what case can an autoimmune condition be reversed?
(2)

Answer 8

If the autoimmune condition is diagnosed in childhood

The condition can burn out in puberty

Question 9

What is an autoantigen?
(3)

Answer 9

An antigen of human

If an antigen is in organ e.g. pancreas it will only manifest locally

If antigen is in areas such as the joint it can be widespread

Question 10

What is systemic disease?

Answer 10

A disease that can manifest anywhere in the body

e.g. systemic lupus erythematosus

Question 11

Give two diseases that affect the nervous system

Answer 11

Multiple sclerosis

Myasthenia gravis

Question 12

Give two diseases that affect the endocrine system

Answer 12

Type 1 diabetes mellitus

Grave’s disease

Question 13

Give two diseases that affect the skin

Answer 13

Psoriasis

Dermatomyositis

Question 14

Give two diseases that affect the GIT

Answer 14

Ulcerative colitis

Crohn’s Disease

Question 15

Give two diseases that affect the bones

Answer 15

Reumatoid arthritis

Sjogren’s syndrome

Question 16

Who do autoimmune disease affect most, males or females

Answer 16

Females

Question 17

How does autoimmunity come about?
(3)

Answer 17

Initiated by a loss of tolerance

Autoreactive T cells should be deleted in the thymus -> in disease they are not -> out of the thymus they cause disease

Patients have some predisposing genetic background

Question 18

Give an example of a mild disease

Answer 18

Psoriasis

Question 19

Give an example of a fatal disease

Answer 19

Primary progressive MS

Question 20

How can you have a predisposition to autoimmune conditions?

Answer 20

Mutations are found on the HLA region -> risk is transferred here

Having the gene does not mean you will have the disease but you will be at a very high risk

Question 21

Give some things that can increase your risk of autoimmunity

Answer 21

Infections can increase the risk of autoimmunity

Question 22

What is diabetes?

Answer 22

Loss of blood sugar control

Question 23

How does insulin work in normal patients

Answer 23

• consumption of food is followed by insulin production
• insulin binds to insulin receptors on cells
• glucose transporters are moved to the cell surface
• available glucose is then taken into the cell

Question 24

What happens in type 1 diabetes?

Answer 24

Insulin production is stopped

Autoimmune

Question 25

What happens in type 2 diabetes?

Answer 25

Insulin resistance develops Usually lifestyle-related

Question 26

What is the main culprit in type 1 diabetes

Answer 26

The autoreactive T cell

Question 27

What roll do autoreactive T cells have in type 1 diabetes

Answer 27

They lead the selective destruction of insulin-producing beta-cells T cells made against antigens in the pancreas- against insulin - against GAD65 - against islet-cell antibodies

Question 28

What roll do B cells have in type 1 diabetes (3)

Answer 28

They produce anti-insulin antibodies They produce anti-glutamic acid decarboxylase 65 (GAD65) antibodies Anti-islet cell antibodies

Question 29

What is GAD65

Answer 29

Glutamic acid decarboxylase 65

Question 30

Why does the T cell attack the beta cells?

Answer 30

T cell acts like the B cell is infected with a virus They only attack the Beta cells

Question 31

Why can we not reverse diabetes at the moment (2)

Answer 31

There is no stem cell for Beta cells However Harvard has been able to make a stem cell into a beta cell -> which hopefully in the future can be put back into the body

Question 32

What three methods are there to diagnosing autoimmune conditions?

Answer 32

The detection of antibodies The detection of generic markers of inflammation - ESR and CRP Measuring other generic marks of health - platelet levels and anaemia

Question 33

What are two generic markers of inflammation?

Answer 33

ESR CRP

Question 34

What are two generic markers of health

Answer 34

Platelet levels Anaemia (rbc count)

Question 35

How do we detect autoantibodies by fluorescence?

Answer 35

Uses commercially available, labelled antibodies to detect patient autoantibodies in serum, or tissue

Question 36

Give some examples of commercially available antibodies (5)

Answer 36

Anti-nuclear antibodies Anti-neutrophil cytoplasmic antibodies Endomysial antibodies Anti-glomerular basement membrane antibodies Lupus skin

Question 37

What is direct immunofluorescence

Answer 37

Detecting antibodies in human tissue samples

Question 38

How do we carry out direct immunofluorescence? (2)

Answer 38

We take a biopsy from a patient Antibodies here are bound to antigen

Question 39

Give an example of how we use direct immunofluorescence

Answer 39

Autoantibodies in the skin of lupus patients

Question 40

What is indirect immunofluorescence?

Answer 40

Detecting antibodies from patient serum

Question 41

How do we carry out indirect immunofluorescence

Answer 41

Antibodies are in serum These react with antigen There is a fluorescent reaction

Question 42

Give an example of how we use indirect immunofluorescence

Answer 42

Used to detect antinuclear antibodies

Question 43

How do we use direct immunofluorescence to detect systemic lupus erythematosus? (4)

Answer 43

Patients with lupus may have antibodies deposited in their skin (butterfly rash) at the dermoepidermal junction A skin biopsy is taken from the patient Biopsy is sectioned and stained with anti-human IgM-FITC antibodies Gives green fluorescence band -> 'lupus band'

Question 44

Where does lupus deposit autoantibodies?

Answer 44

At the dermoepidermal junction

Question 45

What is used to stain for antibodies in lupus?

Answer 45

Anti human IgM FITC antibodies

Question 46

What does a positive test for lupus look like|?

Answer 46

A positive test results in apple green fluorescence at the dermoepidermal junction

Question 47

Explain how we use indirect immunofluorescence to detect anti-nuclear antibodies

Answer 47

Anti-nuclear antibodies are used to diagnose autoimmune connective tissue diseases such as rheumatoid arthritis and lupus

Question 48

How are anti-nuclear antibodies produced (3)

Answer 48

Company grows cells on slide Hep2 cell line These cells have a nice big nucleus so any reaction is easy to see

Question 49

How are autoantibodies detected?

Answer 49

Via immunoassay e.g. ELISA Immunocap

Question 50

Why would ELISA be better than fluorescence detection of antibodies

Answer 50

ELISA is faster, automated and quantitative

Question 51

How does immunocap work?

Answer 51

Each cap is coated with different antigens Add diluted patient sample Wash Add conjugated antibody

Question 52

What type of autoantibodies are used in ELISA?

Answer 52

They tend to be IgG/IgM/IgA in nature

Question 53

How does immunocap assay work? (7)

Answer 53

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