Allergy and asthma

Question 1

Why do we get hypersensitivity?

Answer 1

-consequence of immunological arms race with pathogens

Question 2

What is hypersensitivity?

Answer 2

-where the immune response contributes to disease

Question 3

type 1 hypersensitivity: IgE antibody

Answer 3

• atopic asthma

- hay fever (allergic rhinitis)

Question 4

IgG tissue self-antigen

Answer 4

goodpasture’s syndrome

Question 5

IgG soluble self-antigen

Answer 5

Systematic Lupus Erythematosus (SLE)

Question 6

activated macrophages

Answer 6

pulmonary tuberculosis

Question 7

Diagnosis of IgE allergen sensitivity: Immediate allergen skin prick test responses (10 mins)

Answer 7

Diameter of the raised blanched weal identifies • the profile of allergen sensitivity
• the IgE antibody titre

Question 8

mast cells (mucosal tissue) and basophils (blood)

Answer 8

Mast cells bind IgE to form a functional response unit to allergens/parasites

Question 9

activation of degranulation of mast cells by IgE

Answer 9

Release of
• Histamine
• Chemokines
• Cytokines
• Leukotrienes
• Prostaglandins
 • Growth factors

Question 10

Asthma Histology

Answer 10

• inhaled allergens cause inflammation
• mast cell degranulation
• smooth muscle contraction (wheeze)
• airway remodelling-lumen greatly reduced
• sub-epithelial collagen is thicker
• epithelium is more abundant, along with mucus

Question 11

Asthma

Answer 11

The interstitium (tissue around the bronchiole) has more inflammatory cells (those with pink cytoplasm = eosinophils

Question 12

Eosinophils

Answer 12

• gram stain pink by eosin dye
• IgG and IgE antibody bind to parasite
• eosinophils bind to IgG/IgE on parasite
• release of granule contents on parasite membrane
  i. e. Major Basic Protein (MBP) - toxic for parasites

Question 13

Type 2 hypersensitivity example 1: Hashimoto’s Thyroiditis

Answer 13

-Auto-antibody to thyroid protein (thyroglobulin)
Thyroid
-thyroxine - replacement therapy

Question 14

Type 2 hypersensitivity example 2: Sjogrens Syndrome

Answer 14

• parotid enlargement

- auto-antibodies to antigen* in the glands that produce tears and saliva

Question 15

Type 2 hypersensitivity: Auto-immune haemolytic anaemia

Answer 15

-acquired autoimmune disease

Question 16

Farmers lung

Answer 16

-type 3 hypersensitivity
-exogeneous antigen (serum sickness)
Mechanism:
1. Repeated inhalation of antigen
2. Generates IgG antibody response in lung
3. Binding of antigen by antibody in the lung causes local inflammation

Question 17

Type 4 hypersensitivity example: Pulmonary Tuberculosis (TB)

Answer 17

-caused by bacteria (Mycobacterium tuberculosis) mostly affect the lungs.
• the second greatest killer worldwide due to a single infectious agent
-spread by coughing

Question 18

Tuberculosis -cellular mechanism

Answer 18

TB antigens are recognised by lung T-cell (CD4+ T helper 1 lymphocyte) This activated T-cell releases cytokines:

1. Tumour necrosis factor (TNF) which recruits monocytes from blood
2. Interferon-gamma (IFNγ) that activates monocytes to become macrophages
3. IFNγ is a powerful activator of macrophages which the secrete cytokines to recruit T cells.
4. TNF stimulates local inflammation and together stimulate granuloma formation