Hypersensitivites Flashcards
Overview of Type 1:
Sensitized phase: Exposed to Ag. Plasma cells secrete IgE, which bind to FcR on mast cells. When exposed to Ag again, Ag will bind to receptor on mast cell = degranulation.
Could lead to asthma, urticaria(hives), eczema, or anaphylaxis.
Overview of Type II:
Antibody mediated cytotoxic response. Tissue specific.
Abnormal IgG and IgM produced against specific tissues.
1-3 All involve complement
1-4 Involve cytotoxic cell killing
- Complement mediated lysis = hemolytic disease of newborn.
- Opsonization and phagocytosis
- Neutrophil mediated.
- ADCC. Cytotoxic cells with FcR bind to the Fc portions of the Antibodies that are bound to Ag.
- Indued cell malfunction. Myasthenia gravis, graves.
Overview Type III: Immune Complex (Ag: Ab)
Ab-Ag complexes get stuck in kidney, vessel walls, or other filtration tissues. Usually IgG or IgM.
- Systemic: Serum, raynauds.
- Localized: Arthus. Farmers Lung.
- Immune Diseases: Infectious or Autoimmune (SLE, AR)
- Ocular manifestations (uveitis, scleritis)
Overview Type IV: Delayed/Cell mediated
Mediated by T cell lymphocytes.
Direct: CTLs
Indirect: Th1 activates MO
- Environmental- contact dermatitis.
- TB skin test
- Autoimmune- Chrons, MS, type I diabetes
- Ocular. Uveitis, scleritis, optic neuritis.
2 main categories of hypersensitives
1-3: Immediate. Ab mediated.
4: Delayed. Does not involve Ab.
Symptoms of type 1 sensitivity
Puritis (itching) Angioedema Urticaria (hives) Conjunctivitis Rhinitis (stuffy nose) Hypotension Low BP Bronchospasm Dysrhthmias GI cramps
2 treatments of type 1 hypersensitivity
- Desensitization: Will increase threshold, but you will still be allergic.
- Tolerance: Longer term change. No longer allergic.
What does anaphylaxis do to the body? How does an epipen help?
Anaphylaxis causes blood vessels to dilate due to histamine, BP drops.
Constrict blood vessels, relaxes smooth muscle, stimulates Heart beat and reduces swelling.
3 Chronic diseases of Type I
Allergic asthma (bronchioles constrict and have increased secretions) Chronic urticaria (hives) Eczema
Type II. Example of complement mediated lysis?
Hemolytic disease of the newborn
How does Type II cause induced cell malfunction
Ab attack self and change the function. Causes increase or decrease in cell activity. Problematic for cells that need to turn on or off.
Type II induced cell malfunction Myasthenia Gravis
Abs block Ach receptors on muscle cell at NMJ. Prevents ACh release. Causes muscles to become weak. Ptosis, diplopia, trouble swallowing, and easily fatigued.
Type II induced cell malfunction Graves
Ab stimulate thyroid cells to over produce thyroid hormone. Causes goiter, increased metabolism, lid retraction and increased sympathetic activity.
Type II. 3 examples that involve complement
- Complement mediated lysis
- Opsonization/Phagocytosis
- Neutrophil mediated
Type II. 4 examples that involve Cytotoxic cell killing.
- Complement mediated lysis
- Opsonization/Phagocytosis
- Neutrophil mediated
- ADCC.
Requirements for hypersensitivity
Have to be genetically predisposed.
Initial exposure alters immunologic homeostasis.
Anaphylaxis mild reactions and severe reactions
Mild:
Itching, hives, erythema (red skin), Contraction of bronchioles
Severe (multi-organ):
Laryngeal edema, vascular collapse, death
Type II
Infections (1)
Autoimmune (2)
Alloimmune (2)
Infections: rheumatic fever
Autoimmune: Myasthenia gravis, graves
Alloimmune: Graft rejection, hemolytic disease of the newborn.
Key about type II
IgM or IgG directed against antigens on SPECIFIC tissues/cells.
Type III immune complexes are cleared how?
Large
Small
Intermediate
Large: MO
Small: Renal
Intermediate: Deposit in tissues
Type III Systemic (2)
- Serum. IV drugs
2. Raynauds. Temp dependent immune complex deposition in peripheral (cooler) capillary beds.
Type III localized
Arthus rxn- farmers lung
Type III autoimmune diseases
SLE, RA, Sjogrens
Ocular manifestations of Type III
Uveitis, scleritis, ischemic optic neuropathy, peripheral ulcerative keratitis
Type III infectious
- Poststreptococcal glomerulonephritis causes compromised kidney function due to strep infection.
- Polyarteritis nodosa
- Reactive Arthritis
Environmental antigens Type I Type II Type III Type IV
I: pollens, mold, fungi, foods, animals
II: Antibiotics, latex. PCN binds to plasma membranes on RBCs or platelets. Usually against happens that bind to the surface of cells. IgG or IgM response.
III: Vaccines, Arthus (Farmer’s Lung- mold related in lungs)
IV: Plant resins, metal, chemicals. Mostly happens. Usually proteins found in skin.
Most allergies are Type
I
