Download Chapter 18 BauPP

277
Chapter 18
Immune Disorders
• Allergy (Hypersensitivity):
• Allergen:
• How does an allergen enter the body?
3I, 1C
277
Antibody-Mediated
Cell-mediated
(Immediate-type)
(Delayed-type)
1. Few seconds to
1. one to several days
24 hours.
2. Involves the release
2. No
of histamine.
3. Occurs in blood
vessels, connective
tissues and smooth
muscles.
3. Anywhere
Antibody-mediated
Cell-mediated
(Immediate-type)
(Delayed-type)
4. Can be transferred
4. No
with serum that
contains IgE.
5. Cannot be transferred
with lymphocytes.
6. Type I, type II and
type III.
5. Can be transferred
with lymphocytes.
6. Type IV
278
Physiology of IgE-mediated Allergy:
1. Allergen enters the body.
2. The immune system produces IgE.
3. The IgE attaches to the mast cell and
basophil.
4. The cells are described as being sensitized.
Insert figure 16.3
Cellular reactions
278
5. The next time the same allergen enters the
body again.
6. The allergen connects to the IgE.
7. The binding activates the cells to undergo
degranulation.
8. The chemical mediators (histamine,
bradykinin, serotonin, leukotriene, heparin)
are released from the sensitized cells.
It is due to these chemicals that cause the
allergic reaction.
279
Type I Allergy
Atopic Diseases:
Hay fever:
Asthma:
Atopic dermatitis (eczema):
Food allergy:
Drug allergy:
Anaphylaxis (anaphylactic shock):
280
Diagnosis of Type I Hypersensitivity:
Skin testing:
Desensitization or hyposensitization:
1. IgG removes allergen from the system.
2. IgE combines with allergen and prevents
it from reacting with the mast cells.
3. Allergen induces clones of suppressor T cells
which block the production of IgE by B cells.
Diagnosis of Allergy
• Important to determine if a person is experiencing
allergy or infection
• Skin testing
9
281
Type II Allergy
Mismatch in:
ABO system:
Blood transfusion
Rh system:
Erythroblastosis fetalis
281
Blood Types
Agglutinogens
Agglutinin
A
A
B
B
B
A
AB
A and B
None
O
None
A and B
1. Recipient ------- Antibody?
2. Donor ----------- Antigen?
3. Compare Antigen and Antibody
Homologous ---- Reaction (clumping)
Incompatible (cannot donate blood)
282
Type III (immune complex-mediated) Allergy
Mechanisms:
The immune complexes precipitate in the
basement membranes of epithelial tissues. The
neutrophils release lysosomal granules to
digest the tissues and cause a destructive
inflammatory conditions.
283
Type III Allergy
Arthus reaction (antibody excess):
Serum sickness (antigen excess):
Hypersensitivity Pneumonitis:
Glomerulonephritis:
Rheumatoid Arthritis:
Systemic Lupus Erythromatosus (SLE):
Figure 18.9 The crippling distortion of joints characteristic of rheumatoid arthritis.
Figure 18.10 The characteristic facial rash of systemic lupus erythematosus.
284
Type IV/Delayed-Type Allergy
Infectious Allergy (Allergy of Infection):
Contact Dermatitis:
Figure 18.11 A positive tuberculin test, a type IV hypersensitivity response.
Figure 18.12 Allergic contact dermatitis, a type IV hypersensitivity response.
285
Major histocompatibility complex (MHC or HLA):
Type I and type II genes are responsible for
recognition of self and regulation of immune
response.
Host-versus-graft reaction:
Graft-versus-host reaction:
285
Type IV (Delayed or Cell-mediated)
Hypersensitivity: Graft rejection
Classes of Grafts:
Autograft:
Isograft (Syngraft, syngenic, isogenic):
Allograft (Homograft):
Xenograft (Heterograft):
Types of grafts
Figure 18.13
286
Tissue Typing:
1. Mixed lymphocyte reaction (MLR):
2. Tissue typing:
a. Lymphoagglutination
b. Lymphocytotoxicity
286
Causes of Autoimmune Diseases:
1. Estrogen may stimulate the destruction of
tissues by cytotoxic cells.
2. Maternal cells may cross placenta and trigger
an autoimmune disease in the fetus.
3. Fetal cells may cross placenta and trigger
autoimmunity in mother.
286
4. The sequestered antigen theory
During embryonic development, some tissues
are hidden behind anatomical barriers and
cannot be detected by the immune system.
Eventually their antigens are exposed due to
infection, trauma or deterioration. They are then
attacked by our immune system.
287
5. The clonal selection theory
The forbidden clones (the lymphocytes that can
react with our tissues) are supposed to be
eliminated. If they survive, they will attack our
own tissues.
287
6. Theory of molecular mimicry
7. Theory of viral infection
288
Examples of Autoimmune Diseases
A. Autoimmunity Affecting Blood Cells:
Autoimmune hemolytic anemia
B. Autoimmunity Affecting Endocrine Organs:
Type I diabetes mellitus (juvenile-onset diabetes):
Type II diabetes (maturity-onset, non-insulindependent diabetes):
Graves’disease: against thyroid gland; excessive
thyroid hormone (results in goiter)
288
C. Autoimmunity Affecting Nervous Tissue:
Multiple sclerosis (MS):
D. Autoimmunity Affecting Connective Tissue:
Rheumatoid arthritis
288-289
Immunodeficiency Diseases:
I. Primary Immunodeficiency Diseases:
1. Chronic granulomatous disease
2. Agammaglobulinemia
(Hypogammaglobulinemia):
3. DiGeorge syndrome (thymic aplasia):
4. Severe combined immunodeficiency (SCID):
289
Secondary Immunodeficiency Disease:
Autoimmunodeficiency syndrome (AIDS):