Immune system of the skin

Question 1

What are the 2 types of skin infection?

Answer 1

1. Primary: when the pathogen is a direct cause of disease
   
   • e.g. demodectic mange caused by mites.
2. Secondary: when infection results from underlying disease
   
   • e.g. allergic disease causing pruritis leading to bacterial pyoderma

Question 2

What is the difference between a superficial and deep pyoderma?

Answer 2

• Superficial: affects the epidermis and hair follicles
• Deep: affects the dermis and/or deep dermis

Question 3

Hypersensitivity reaction

Answer 3

immune responses to innocuous antigens that lead to symptomatic reactions upon re-exposure.

There are various types (I-IV)

Question 4

Type I hypersensitivity

Answer 4

immediate hypersensitivity

Mediated by IgE activating mast cells

Question 5

Type II hypersensitivity

Answer 5

IgG antibodies against the cell surface/matrix antigens

Question 6

Type III hypersensitivity

Answer 6

antigen-antibody complex-mediated

Question 7

Type IV hypersensitivity

Answer 7

T cell mediated

Question 8

True/false: with all hypersensitivity types, there has to have been previous exposure and sensitisation of antibodies or T cells.

Question 9

What are the three types of Type IV hypersensitivity?

Answer 9

1. Contact - antigen at the epidermis
2. Tuberculin - intradermal antigen
3. Granuloma - persistent antigen/foreign body presence