Lecture 16 Allergy

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Lecture 16 Allergy

• Hay fever 20
• Asthma 5

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Figure 10-1
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4 types of hypersensitivity reactions
(hives)
Allergies
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Immune complex disease
Delayed-type hypersensitivity
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Type I hypersensitivity-mediated by mast-cell
degranulation. Preformed granules contain
histamine, heparin, TNF, chondroitin sulfate,
neutral proteases, and other.
Mucosal mast cell/Connective tissue mast cell
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Figure 10-4
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Figure 10-5
In granules
Produced after activation
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Histamine
Binds to histamine receptors H1, H2,
H3-cell-type specific Binding to H1 on
endothelial cells (increased permeability)
smooth muscle (contraction) mucosal epithelium
(mucus secretion)
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Mediators
Neutral proteases activate Metalloproteases -
remodeling of the extracellular matrix TNF-
inflammation Lipid Mediators (PGD2, LTC4) -
inflammation Chemokines (MIP-1a) - chemotaxis of
leukocytes Cytokines - Production of eosinophils,
Th2 cells Proteoglycans, heparin and chondroitin
- sequester mediators, and effect a timed release
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Prostaglandins and leukotrienes
PGD2- vessel dilation and permeability and
chemoattractant for neutrophils LTC4- same as
histamine, but 100x more potent - late response.
Leukotrienes used to be called Slow Reacting
Substance of Anaphylaxis - SRS-A
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Biologic effects of mediators
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Biological effects of Eosinophil mediators
Late stage of an allergic response includes the
recruitment of eosinophils and Th2 cells contrast
with
a DTH (type IV) response which includes
infiltration of macrophages and Th1 cells
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Eosinophils
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Figure 10-9 part 1 of 2
Products released by eosinophils
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Figure 10-10
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Figure 10-12
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Figure 10-14
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Figure 10-16
FEV1 - the forced expiratory volume of air in one
second
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Figure 10-18
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Systemic anaphylaxis
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Use of adrenaline to counteract the effects of
system anaphylaxis
In anaphylactic shock, blood vessels leak,
bronchial tissues swell and blood pressure drops,
causing choking and collapse. Adrenaline
(epinephrine) acts quickly to constrict blood
vessels, relax smooth muscles in the lungs to
improve breathing, stimulate the heartbeat and
help to stop swelling around the face and lips
(angioedema).
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Asthma
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Figure 10-22 part 1 of 2
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Figure 10-22 part 2 of 2
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Histopathology of bronchial asthma
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Treatment of asthma
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New therapy for asthma and allergy blocking the
Fc portion of IgE from binding to the FceR on
mast cells
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Skin test for allergy
Ragweed
Control
Histamine
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Food allergies
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Type II hypersensitivityis caused by antibodies
to altered cell-surface components
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Figure 10-27
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Type III hypersensitivity reactions (Arthus
Reaction)Antibody-Antigen Complexes
Critical mediators appear to be C5a-receptor and
FcgRIII--probably present on mast cells
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Figure 10-31
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Figure 10-29
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Figure 10-32
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Type IV hypersensitivity - Delayed-type
hypersensitivity
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Figure 10-34
Also, note time scale
What is missing from this scheme?
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Figure 10-35
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Figure 10-36
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Figure 10-23