Hypersensitivity Reactions Flashcards
Covering types 1-4 of hypersensitivity
Immunologically-mediated tissue injury leads to…
hypersensitivity reactions
What are the four classes of hypersensitivity reactions?
- Type I Immediate Type (IgE mediated/anaphylactic)
- Type II Cytotoxic
- Type III Immune Complex Mediated
- Type IV Delayed Type (T cell mediated)
Type I hypersensitivity is mediated by which antibody?
IgE
IgE antibodies bind… causing…
bind mast cells, basophils, cross link IgE receptors causing degranulation
Type I hypersensitivity involves a release of various mediators including…
histamine (vasodilator)
Describe the effects of histamine in type I hypersensitivity
- Leads to vascular leakage, especially venules
- The arteriolar dilation leads to hypotension
What are some examples of type I hypersensitivity?
Allergies, anaphylactic reactions
What is one treatment for type I hypersensitivity?
Allergen immunotherapy to reduce specific IgE levels
type I hypersensitivity
With more IgG, there is less…
IgE
type I hypersensitivity
What is the effect of IgE on a mast cell?
Sensitizes the mast cell to an antigen by binding to it
type I hypersensitivity
Upon initial exposure to an antigen, what is the effect on IgE?
Increased IgE production
type I hypersensitivity
Upon subsequent exposure to an antigen, what is the effect on IgE?
Binding to IgE and degranulation of mast cells
type I hypersensitivity
As IgE binds to mast cells, leading to degranulation, what is released?
- Histamine
- Leukotrienes
- Eosinophil chemotactic factor
In type II hypersensitivity, which antibodies will bind to what?
IgG and IgM bind to fixed (not soluble) target antigens (on a host cell surface)
type II hypersensitivity
Initial sensitization, or cross reaction with infectious agent leads to…
Ab production
In type II hypersensitivity, the antibodies bind to “self” antigens and trigger…
complement activation and tissue damage
What does it mean when type II hypersensitivity is called cytotoxic?
Cells are killed
What is an example of a syndrome involving type II hypersensitivity?
Goodpasture syndrome
type II hypersensitivity
What is Goodpasture syndrome?
Autoimmune disease where antibodies are made against glomerular basement membrane destroying kidneys
What are two type II hypersensitivity reactions that do not lead to death but can alter normal physiology?
- Grave disease
- Myasthenia gravis
type II hypersensitivity
What is Grave disease?
- Autoimmune thyroiditis with hyperthyroid
- Anti-TSH-receptor antibodies present
Grave disease
TSH normally functions to…
increase T3 and T4