Introduction to Immunological Diseases

Question 1

What happens during inflammation?

Answer 1

Bacteria trigger macrophages to release cytokines and chemokines

Vasodilation and increased vascular permeability cause redness, heat, and swelling

Inflammatory cells migrate into tissue, releasing inflammatory mediators that cause npain
- Neutrophils and macrophages are the principal inflammatory cells

Question 2

What occurs during the immune response to injury?

Answer 2

1. Bacteria and other pathogens enter the wound
2. Platelets from blood release blood-clotting proteins at the wound site
3. Mast cells secrete factors that mediate vasodilation and vascular constriction. Delivery of blood , plasma and cells to injured area increase.
4. Neutrophils secrete factors that kill and degrade pathogens
5. Neutrophil and macrophages remove pathogens by phagocytosis
6. Macrophages secrete cytokines that attract immune cells to the site, and activate cells involved in tissue repair
7. Inflammatory response continues until the foreign material is eliminated and the wound is repaired

Question 3

What is inflammation?

Answer 3

Inflammation is the recruitment of immune cells to the site of injury or infection

Question 4

Why does inflammation occur?

Answer 4

The cytokines released by the activated macrophages chemo-tactically attract other immune cells
- These help fight the infection

Importantly, they increase the flow of lymph to the affected area
- Antigen presenting cells are carried away from the site of infection to lymphoid tissue where they activate lymphocytes and initiate the adaptive immune response

Question 5

Give examples of non-infectious immunological diseases

Answer 5

Eczema - T cell mediated - increased cytokine levels
Psoriasis - T cell mediated - Filaggrin levels decrease
Vitiligo - Autoimmune? - Cytokine levels increase
Bullous skin disease - Autoimmune - targets connective tissue
Alopecia areata - Autoimmune - targets hair follicles

Question 6

What is primary immunodeficiency?

Answer 6

Immunodeficiency caused by an intrinsic defect of genetic origin (e.g. missing enzyme, missing cell type, or non-functioning component)

Question 7

Give an example of primary immunodeficiency

Answer 7

Transient hypogammaglobulinaemia of infancy

• Maternal IgG protects the foetus/infant during pregnancy/early life
• Passed across the placenta
• When babies are premature less IgG is transported from the mother
• If the baby is slow to synthesise IgG the infant will be susceptible to pyogenic (pus) infections

Question 8

What is secondary immunodeficiency?

Answer 8

Immunodeficiency that is acquired

• Malnutrition / Infection
• Drugs (immunosuppressive)
• Lymphoproliferative disease

Question 9

Give an example of secondary immunodeficiency

Answer 9

AIDS

• HIV virus infects CD4 T Helper cells (Th)
• T Helper cells produce cytokines and are important for the function of the immune system
• HIV virus infection directly kills CD4 T cells
• CD8 T Cells kill virally infected cells
• Progressive reduction in the number of CD4 T Helper cells
• At

Question 10

What are the different types of hypersensitivity?

Answer 10

I, II, III, IV

Question 11

Describe type 1 hypersensitivity

Answer 11

IgE-mediated hypersensitivity

• IgE is bound to mast cells via its Fc portion. When an allergen binds to these antibodies, crosslinking of IgE causes degranulation
• Causes localised and systemic anaphylaxis, seasonal allergies including hayfever, food allergies such as those to shellfish and peanuts, hives and eczema