Immune Disorders Flashcards
How many types of hypersensitivity mechanisms are there?
4
What is a hypersensitivity reaction?
An exaggerated or inappropriate adaptive immune response to an antigen/immunogen causing tissue damage
What are the 4 types of hypersensitivity reactions?
Immediate (type I) Cytotoxic (type II) Complex mediated (type III) Delayed (type IV)
Which antibody mediates Type I hypersensitivity reactions?
Ig E
Which antibody mediates Type II hypersensitivity reactions?
IgG
IgM
Which antibody mediates Type III hypersensitivity reactions?
IgG
IgM
Which antibody mediates Type IV hypersensitivity reactions?
T lymphocytes
Macrophages
What is anaphylaxis?
Generalised type I reaction, which leads to vasodilation and constriction of bronchial smooth muscle
What type sensitivity is cytotoxic?
Type II
What does complement activation lead to?
Cell lysis
Depositation of complement components
Macrophage and neutrophil activation
What is haemolytic disease of the newborn?
Rhesus incompatibility
What are the effects of rhesus incompatibility?
Spontaneous abortion
Baby born with mild jaundice or HDN
What type of hypersensitivity is immune complex hypersensitivity?
III
When would type III hypersensitivity occur?
Persistent infection
Autoimmunity
What nature can immune complexes be?
Precipitates
Soluble
What are intrinsic allergic alveolitis?
An occupational disease due to inhalation of immunogenic proteins or spores
What are examples of intrinsic allergic alveolitis?
Farmers lung
Mushroom worker disease
Coffee worker disease
What causes farmers lung?
Sensitisation to thermophilic actinomycetes spores from damp hay, years of exposure lead to high circulating levels of IgG and spore antigens. These complexes precipitate in the lung
How does the precipitate in farmers lung cause emphysema (irreversible lung damage)?
Complement activates
Initiates inflammation
Destroys alveolar tissue
Fibrosis (tissue repair)
What causes serum sickness?
Treatment of an active infection with antibodies
How long before serum sickness symptoms develop?
7 days
What are the symptoms of serum sickness?
Weakness, fever, skin rash, oedema
What type of of hypersensitivity is contact hypersensitivity?
Type IV
How long does type IV hypersensitivity take to develop?
72hrs to weeks
What is contact hypersensitivity mediated by?
T lymphocytes and macrophages
What can cause dermatitis (a type of contact hypersensitivity)?
Biological stains
Hair dyes
Urushiol (Poison ivy)
What is sensitisation?
Initial contact leads to a cell mediated immune response
What is autoimmunity?
A breakdown of self tolerance
What is self tolerance?
Failure to respond to self antigens
What are the two types of self tolerance?
Central tolerance
Peripheral tolerance
What characterises central tolerance?
Deletion of self reactive T cells
What characterises peripheral tolerance?
Clonal anergy
Deletion
Active suppression
Presence of autoreactive B cells
What causes the stimulation of self reactive lymphocytes?
Failure to eliminate self reactive lymphocytes
Failure of suppression
Occur after microbial infections
What are the two types of autoimmunity?
Organ specific
Systemic
What characterises organ specific autoimmunity?
Auto antigen localised to one organ
What factors influence susceptibility to autoimmunity?
Genetics
Environmental
Hormonal
What are the two types of immunodeficiency?
Primary
Acquired/secondary
What characterises primary immunodeficiency?
T cell defect
B cell defect
Phagocytosis defect
Complement defect
What causes secondary immunodeficiency?
Malnutrition
Treatment eg. X-rays
Infection (HIV)
