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Flashcards in HS IV Deck (14):
1

What type of reaction is a type IV hypersensitivity reaction?

Delayed reaction, due to involvement of lymphocytes and macrophages

2

How long does it take for a type IV hypersensitivity reaction to occur?

1-3 days

3

What immune cells are involved in type IV hypersensitivity reactions and how do they cause tissue damage?

Lymphocytes and macrophages
-Macrophages antigen present, activating naive T cells to become memory and antigen specific TH1 cells
-Activated T cells release cytokines which attract macrophages and cause tissue damage

4

Define contact hypersensitivity

Epidermal reaction causing eczematous rash in response to exogenous antigen

5

What is a tuberculin hypersensitivity?

A dermal reaction producing swelling and induration (hardened mass)

6

What is a granulomatous hypersensitivity?

Persistence of antigens causing tissue damage, involves walling off infected cells by forming a granuloma of T cells containing macrophages

7

What causes a granulomatous hypersensitivity and how long does it take to develop?

Infection with TB, leprosy or schistosomiasis, or sarcoidosis

8

How does the Mantoux/Lepromin test work?

-Antigen injected into the subcutaneous tissue
-TH1 effector cell recognises antigen and releases cytokines
-Recruitment of phagocytes to injection site
-Visible red bump indicates sensitisation

9

Describe the pathophysiology of Hashimoto's disease

Presence of CD8+ T cells and autoantibodies against thyroid cells
Release of cytokines and activation of macrophages damages thyroid tissue, causing hypothyroidism

10

Describe the features of hypothyroidism

Weight gain
Fatigue
Myalga/Arthralga
Decreased appetite
Cold intolerance

11

What antibodies are tested for in Hashimoto's disease?

Anti-thyroglobulin antibody
Anti-thyroid peroxidase antibody

12

Describe the likely results of a biopsy of a thyroid gland with Hashimoto's disease

Infiltrate of lymphocytes (CD4+ and CD8+)
Plasma cells

13

How is Hashimoto's disease tested?

Replacement therapy with thyroxine
Monitor TSH levels

14

What cells are damaged in insulin dependant diabetes mellitus?

Pancreatic islet cells