NR507 Advanced Pathophysiology MidTerm
1. Hypersensitivity: Type 1: Type 1: Allergic reaction, Mediated by IgE, Inflammation due
to mast cell degranulation
Local symptoms:
-itching
-rash
Systemic symptoms:
-wheezing
Most dangerous = anaphylactic reaction
systemic response of hypotension, severe bronchoconstriction
Main treatment: epinephrine reverses the effects
2. Hypersensitivity: Type 2: Type 2: Cytotoxic reaction; tissue specific (ex: thyroid tissue)
Macrophages are the primary effectors cells involved
Can cause tissue damage or alter function
Grave's disease (hyperthyroidism) - example of altering thyroid function, but does not
destroy thyroid tissue
Incompatible blood type- example of cell/tissue damage that occurs; severe transfusion
reaction occurs and the transfused erythrocytes are destroyed by agglutination or
complement-mediated lysis.
3. Type 1 Hypersensitivity VS. Type 2 Hypersensitivity: Type 1 Hypersensitivity
Organ Specific
Antibody binds to the antigen on the cell surface
Type 2
Hypersensitivity Not
Organ Specific
Antibody binds to the soluble antigen outside the cell surface that was released into the
blood or body fluids, and the complex is then deposited in the tissues
, NR507 Advanced Pathophysiology MidTerm
4. Hypersensitivity: Type 3 - Examples: Rheumatoid arthritis: Antigen/antibodies are
deposited in the joints
Systemic Lupus Erythematosus (SLE)- very closely related to autoimmunity-
antigen/antibodies deposit in organs that cause tissue damage
5. Hypersensitivity: Type 4: Delayed response
Does not involve antigen/antibody complexes like Types 1, 2 and 3
Is T-cell mediated
6. Differentiating Between the Rash of a Type 1 vs. Type 4 Reaction:: Type 1: Imme-
diate hypersensitivity reactions, termed atopic dermatitis, are usually characterized by
widely distributed lesions Type 4: Contact dermatitis (delayed hypersensitivity) consists
of lesions only at the site of contact with the allergen
The key determinant is the timing of the rash:
-Type 1 = Immediate
-Type 4 = Delayed: Several days following contact, ex would be poison ivy
7. Treatment of Type 4 Rash: A non-severe case of contact dermatitis would be treated
with topical corticosteroid.
Why not epinephrine or antihistamines?
-Epinephrine is for emergent Type 1 anaphylactic reactions. Antihistamines act on the H1
receptors. Type 4 does not involve mast cells and H1 receptors.
Antibiotics not appropriate since not an infection
8. Autoimmunity: Autoimmune disease can be familial, Affected family members may not
all develop the same disease, but several members may have different disorders
characterized by a variety of hypersensitivity reactions, These include autoimmune and
allergic reactions
Associations with particular autoimmune diseases have been identified for a variety of
major histocompatibility complex (MHC) alleles or non-MHC genes
1. Hypersensitivity: Type 1: Type 1: Allergic reaction, Mediated by IgE, Inflammation due
to mast cell degranulation
Local symptoms:
-itching
-rash
Systemic symptoms:
-wheezing
Most dangerous = anaphylactic reaction
systemic response of hypotension, severe bronchoconstriction
Main treatment: epinephrine reverses the effects
2. Hypersensitivity: Type 2: Type 2: Cytotoxic reaction; tissue specific (ex: thyroid tissue)
Macrophages are the primary effectors cells involved
Can cause tissue damage or alter function
Grave's disease (hyperthyroidism) - example of altering thyroid function, but does not
destroy thyroid tissue
Incompatible blood type- example of cell/tissue damage that occurs; severe transfusion
reaction occurs and the transfused erythrocytes are destroyed by agglutination or
complement-mediated lysis.
3. Type 1 Hypersensitivity VS. Type 2 Hypersensitivity: Type 1 Hypersensitivity
Organ Specific
Antibody binds to the antigen on the cell surface
Type 2
Hypersensitivity Not
Organ Specific
Antibody binds to the soluble antigen outside the cell surface that was released into the
blood or body fluids, and the complex is then deposited in the tissues
, NR507 Advanced Pathophysiology MidTerm
4. Hypersensitivity: Type 3 - Examples: Rheumatoid arthritis: Antigen/antibodies are
deposited in the joints
Systemic Lupus Erythematosus (SLE)- very closely related to autoimmunity-
antigen/antibodies deposit in organs that cause tissue damage
5. Hypersensitivity: Type 4: Delayed response
Does not involve antigen/antibody complexes like Types 1, 2 and 3
Is T-cell mediated
6. Differentiating Between the Rash of a Type 1 vs. Type 4 Reaction:: Type 1: Imme-
diate hypersensitivity reactions, termed atopic dermatitis, are usually characterized by
widely distributed lesions Type 4: Contact dermatitis (delayed hypersensitivity) consists
of lesions only at the site of contact with the allergen
The key determinant is the timing of the rash:
-Type 1 = Immediate
-Type 4 = Delayed: Several days following contact, ex would be poison ivy
7. Treatment of Type 4 Rash: A non-severe case of contact dermatitis would be treated
with topical corticosteroid.
Why not epinephrine or antihistamines?
-Epinephrine is for emergent Type 1 anaphylactic reactions. Antihistamines act on the H1
receptors. Type 4 does not involve mast cells and H1 receptors.
Antibiotics not appropriate since not an infection
8. Autoimmunity: Autoimmune disease can be familial, Affected family members may not
all develop the same disease, but several members may have different disorders
characterized by a variety of hypersensitivity reactions, These include autoimmune and
allergic reactions
Associations with particular autoimmune diseases have been identified for a variety of
major histocompatibility complex (MHC) alleles or non-MHC genes
