Flashcards in HS IV Deck (14):
What type of reaction is a type IV hypersensitivity reaction?
Delayed reaction, due to involvement of lymphocytes and macrophages
How long does it take for a type IV hypersensitivity reaction to occur?
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
Define contact hypersensitivity
Epidermal reaction causing eczematous rash in response to exogenous antigen
What is a tuberculin hypersensitivity?
A dermal reaction producing swelling and induration (hardened mass)
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
What causes a granulomatous hypersensitivity and how long does it take to develop?
Infection with TB, leprosy or schistosomiasis, or sarcoidosis
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
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
Describe the features of hypothyroidism
What antibodies are tested for in Hashimoto's disease?
Anti-thyroid peroxidase antibody
Describe the likely results of a biopsy of a thyroid gland with Hashimoto's disease
Infiltrate of lymphocytes (CD4+ and CD8+)
How is Hashimoto's disease tested?
Replacement therapy with thyroxine
Monitor TSH levels