Immunology for NL 2009
Surasak Wongratanacheewin,
sura_wng@kku.ac.th
You must know (at least)
• Hypersensitivity
• Ab- IgG, IgM (Immunization and vaccines)
• Primary and secondary immune response
• T cell recognition to MHC I, II
• Immunity to infections
• Serological methods
• Transplantation
• Autoimmunity
Hypersensitivity
• Immediate Hypersensitivity • Delayed-Type Hypersensitivity
Reactions Reactions
• Anaphylactic reactions of • Inappropriate reactions of the
humoral immune response cell-mediated immune response
• Symptoms manifested within • Symptoms manifested sometime
minutes to hours of antigen after 24 hours of antigen
recognition recognition
• Different antibody isotypes • Effector molecules are the
induce different immune effector cytokines secreted by activated
molecules TH or TC cells
• Type I (IgE mediated), Type II • Type IV (cell mediated
(antibody-mediated) and Type III hypersensitivity)
(immune complex-mediated)
Hypersen I
• Type I, IgE-Mediated Hypersensitivity
• Abnormal humoral response induced by allergens
• Allergens: non-parasitic antigen capable of stimulating
type I hypersensitivity in allergic people
• Atopy: hereditary predisposition to develop immediate
hypersensitivity reactions to common environmental
antigens
Hypersen I
• Mechanisms triggering
degranulation of mast cells
• Generally initiated by
allergen cross linking bound
IgE
• Other initiators:
• Anaphylatoxins (C3a, C4a,
C5a)
• Drugs
• What are the mediators released by mast cells and basophils?
• Ex. Histamine binding to H1, H2, H3 receptors, Leukotrienes and
prostaglandins (degranulation leads to synthesis), cytokines (alter local
inflammation and recruit neutrophils and eosinophils)
Hypersen I
• Location of allergic
responses
• On mucous membranes in
response to inhaled or
ingested antigens
• Allergen are diverse in
structure
• Complex interactions
results in allergic
response;
Hypersen I
• Type I Reactions are systemic or • Localized Anaphylaxis (Atopy)
localized
• Reaction is limited to specific
• Systemic Anaphylaxis
tissue or organ
• Shock-like and often fatal
• Tendency for localized response is
• Rapid onset inherites (atopy)
• Contraction of smooth muscle (GI
and bladder), vasodilation (drop • Types: allergic rhinitis (hay fever),
in blood pressure), bronchiole asthma, eczema (atopic
constriction (asphyxiation) dermatitis), and food alergies
• Edema, shock and bronchiole
constriction lead to death • Late phase reactions induce
localized responses
• Treatment: epinephrine
• Localized inflammation following
granulation
• Controlling type I reactions
• Avoidance of allergens
• Immunotherapy with repeated subcutaneous injections doses of allergens
(generation of an IgG blocking Ab)
• Use of drugs to inhibit biochemical steps leading to degranulation
Hypersen II
• Type II Hypersensitivity • Three types
• IgG-Mediated Cytotoxic
Hypersensitivity • Transfusion reactions
• Antibody-mediated destruction of
cells • Hemolytic disease of
newborns
• Can activate complement
• Can mediate cell destruction by • Drug-induced hemolytic
antibody dependent cell-mediated anemia
cytotoxicity (ADCC)
• Antibody serves as an opsonin;
phagocytic cells with FcR or C3bR
bind and phagocytose coated cells
Hemolytic disease of newborns
• Drug-induced hemolytic anemia
• Antibiotics can adsorb to RBC membrane proteins and
form hapten-carrier like complexes
• Antibodies can be formed to these complexes and
stimulate the lysis of the RBCs leading to anemia
Hypersen III
• Immune complex-mediated hypersensitivity
• Antigen-antibody complexes facilitate clearance by
phagocytosis
• Large amounts of immune complexes can result in
enhanced immune response leading to tissue
damage
• Localized reaction, Arthus reaction,
develop when complement is
activated
• C3a, C4a, C5a cause localized mast
cell degranulation and increased
vascular permeability
• C3a, C5a, C5b67 are chemotactic
factors for neutrophils
• Tissue damage is due to the release
of lytic enzymes by neutrophils as
they phagocytose the immune
complex
• Response to insect bites (rapid type I
followed by slower type III)
• Type III: pronounced edema and
erythema
• Immune complex-mediated
hypersensitivity
• Generalized immune response
• Large amounts of antigen
enter the blood
• Formation of circulating
immune complexes
• Generation of antibodies to
foreign serum proteins
• Development of serum
sickness, autoimmune disease,
drug reactions, infectious
disease
Hypersen IV
• Initiated by cytokines secreted by subgroups of TH
cells
• Characteristics
• delayed onset of response
• large influx of macrophages and Langerhans cells
• Necessary and detrimental tissue damage
Primary and Secondary IR
Autoimmunity
Immunization
Complement
Immunity to infections
Bacterial infections
Viral infections
APC and spleen, lymph node
MHC class I/CD8 MHC class II/CD4
Endogeneous Ag Exsogeneous Ag
Spleen or lymph node
Cytokines
• Therapeutic use of
cytokines
• Organ transplantion
• Inflammation
• Cancer therapy
• Infectious disease
• Allergy