4. Type I Hypersensitivity
• Type I (immediate type) reactions
include: asthma, hay fever, food
allergy
• Also referred to as atopy
• Triggered within minutes of
exposure to a variety of
environmental antigens e.g.
pollen, house dust mite
• Strong genetic link
• Caused by an overproduction of
IgE
5. Type II Hypersensitivity
• Antibody mediated
hypersensitivity
• Antibody directed against
membrane and cell surface
antigens (autoantibodies)
• Antigen-antibody reactions
activate complement producing
membrane damage
• Examples include: transfusion
reactions and haemolytic disease of
the newborn
6. Type III Hypersensitivity
• Immune complex mediated
• Excessive formation of immune
complexes e.g. pesistent low-grade
infection, repeated inhalation of
antigens
• Examples of Type III
hypersensitivity include: Farmers
lung, immune complex
glomerulonephritis
7. • Delayed type hypersensitivity
• Takes more than 12 hrs to develop
after antigenic challenge
• Examples include: contact
dermatitis and tuberculin reaction
• Antigens include large molecules
or small molecules (haptens)
linked to carrier molecules
Type IV Hypersensitivity
8. Autoimmunity
• Autoimmunity is a reaction of
the immune system to the
bodies own tissues
• Self molecules are recognised
as antigens due to a breakdown
of self-tolerance
• Antibodies (autoantibodies)
react against these components
• Includes organ-specific and
non-organ specific diseases
9.
10.
11. Immunodeficiency
• An immunopathologic condition
• A deficiency in number,
function, or interrelationships of
the involved WBC’s and their
products
• May be congenital or acquired
• Infections and tumors may
occur as a result of the
deficiency.
