Immunopathology

Question 1

Type 1 hypersensitivity

Answer 1

Rapid immune response to allergen
Host has pre-existing IgE to allergen
Causes a localised response; hives, blisters,nasal discharge,
Can cause a systemic response - anaphylaxis

Question 2

Allergens causing type one hypersensitivity

Answer 2

Proteins often proteases
Low dose may favour IL-4 producing Th2 responses
Low molecular weight and highly soluble; so can diffuse into mucus
Very stable - so can survive in desiccated particle
Contain peptides that can bind MHC class II

Question 3

Anaphylaxis

Answer 3

Systemic response to allergens
Vasodilation occurs due to histamine -> results in hypotension, oedema
Bronchoconstriction

Question 4

Treatments for anaphylaxis

Answer 4

IV fluids, adrenaline, corticosteroids, beta-agonists

Question 5

Types II, III, IV hypersensitivity

Answer 5

Autoimmunity

Question 6

Autoimmunity

Answer 6

Immunity misdirected at the healthy cells and tissues

Mainly caused by failure of self tolerance due to: genetic susceptibility and environmental triggers

Question 7

Factors initiating autoimmunity

Answer 7

Infection - release of sequestered antigens, upregulation of co-stimulators

T-cell by bypass by…
Modification-Neoantigen generated by binding of a pathogen to a self component
Inflammation-immunostimulatory environment activates self reactive t-cells
Molecular mimicry - antibodies or T-cells generated in response to infection cross-react with self

Question 8

Characteristics of autoimmune disease

Answer 8

Chronic disease with relapse and remission

Clinical symptoms shaped by nature of the immune response

Question 9

Type II hypersensitivity

Answer 9

Antibodies formed against altered component on host cells - IgG or IgM

Host IgG or IgM binds to host cells and accelerate cell clearance by; phagocytosis, antibody-dependent cellular cytotoxicity or complement lysis

Question 10

Grave’s disease

Answer 10

IgG antibodies against thyroid stimulating hormone

Question 11

Type III hypersensitivity

Answer 11

Immune complex mediated disease

Complexes arise from persistent infection or inhalation and long term exposure to proteins -> antigen free in circulation form antigen/antibody complexes

Formation of immune complexes-> deposition of immune complexes in tissues-> immune complex mediated inflammation and tissue damage

E.g. lupus

Question 12

Type IV hypersensitivity

Answer 12

delayed type hypersensitivity 1-3 days after

T-cell mediated

can cause local reaction and infection -> granuloma formation in Tb

Question 13

Tuberculin reaction

Answer 13

Exposure to tubercule bacilli -> CD4+ T cell and macrophage accumulation with associated cytokine expression (IFN gamma and TNF) -> epithelioid macrophages surrounded by lymphocytes -> cause granulomas