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59 Cards in this Set

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Describe the sensitization of process type I hypersensitivity.
Sensitization: allergens are processed by APCs and presented to Th2 which release cytokines. IL-4 causes plasma cells to switch from IgM to IgE. IL-5 stimulates the production and activation of eosinophils. IgE-Fc binds to mast cells.
Describe what happens during the reexposure phase of type I hypersensitivity.
Allergen-specific IgE Abs are bound to mast cells. Allergen binds and crosslinks IgE Abs. Mast cells release preformed mediators: histamine (swelling, SMC contraction, bronchoconstriction). Mast cells synthezise PG's and LT's which initiate a late phase reaction (> 6 hrs).
What are atopic individuals?
Those who have a predisposition to develop localized immediate hypersensitivity to a variety of allergens.
What are signs/symptoms of type I hypersensitivity reactions? Anaphylaxis?
Hay fever, eczema, hives, asthma, urticaria, dyspnea, edema, tachypnea, tachycardia.

Hoarseness, vomiting, nausea, abdominal cramps, diarrhea, hypotension and shock.
What are the mediators of the late phase reaction in type I hypersensitivity?
PGD: bronchospasm, mucus secretion
PAF: leukocyte migration/activation
LT-C,D: spasmogenic of smooth muscle cells
LT-B: chemotactic
What is the difference between urticaria and angioedema?
Urticaria is edema in the superficial dermis: small wheals with a pale center encircled by a red flare.
Angioedema is edema in the deep dermis.
How does epinephrine treat type I hypersensitivity? Diphenhydramine? Methylprednisolone?
Epi: Positive beta-2 adrenergic effects: bronchodilator. Positive alpha 1 adrenergic effects: constricts small blood vessels which acts to raise BP.
Diphenhydramine is an H1 receptor antagonist.
Methylprednisolone: upregulating adrenergic receptors, blocks phospholipase A2 (blocks late phase)
What is nedocromil?
Mast cell stabilizer. Prophylactic inhibitors of mast cell degranulation. Cromolyn sodium is another drug that inhibits degranulation of mast cells.
What is the most sensitive test used to evaluate type I hypersensitivity?
Skin prick test.

Radioimmunosorbent test are used to detect specific IgE Abs in the serum.
What is type II hypersensitivity?
Antibody-dependent cytotoxic reactions. Mediated by antibodies directed toward antigens present on cell surfaces or extracellular matrix.
Type II hypersensitivity: complement-dependent, complement independent?
1) ABO mismatch
2) Helminth destruction
3) Grave's disease
4) Drug induced warm autoimmune hemolytic
1) Dependent: IgG activates complement - lysis by MAC
2) Independent: IgE ADCC
3) Independent: IgG abs directed against cell surface receptors.
4) Can be complement dependent, but it is often independent
Name the opsonins.
IgG, C3b, C4b
What test is used to evaluate type II hypersensitivity?
Direct Coombs: detects IgG or C3b attached to RBCs
Indirect Coombs: detects abs in serum
What is the pathogenesis of type III hypersensitivity?
First exposure to antigen produces Abs. Second exposure leads to deposition of Ag-Abs. Complement is activated producing C5a which attracts neutrophils that damage tissue.
Patient presents with widespread urticaria, fever, swollen lymph nodes and painful, swollen ankles. Labs show proteinuria, hematuria, and his complement C1q and C3 levels are decreased. History reveals he was given an antitentanus immune serum. Diagnosis?
Serum sickness. He was injected with horse antitetanus immmune serum and developed a type III hypersensitivity. Ag-Abs deposited and activated the complement system. Anaphylotoxins C3a and C5a caused edema and urticaria.
Does type III hypersensitivity reactions require previous exposure to antigen in order to occur?
No. Sensitization must occur, but if a significant amount of immune-complexes are formed (i.e. from serum sickness) then a type III reaction could occur 2-10 days after the injection.
What tests are used to evaluate type III hypersensitivity?
Immunofluorescent staining of tissue biopsies. Complement levels. WBC count.
What is type IV hypersensitivity?
Cell-mediated delayed hypersensitivity: Th1 cells activate macrophages resulting in cytokine injury to tissue.
Cell-mediated cytotoxicity: Tc cells interact with altered MHCI Ags on neoplastic, virus-infected, donor graft cells causing lysis.
Describe the differences between atopic dermatitis and contact dermatitis.
Atopic dermatitis is a type I hypersensitivity with a fast onset and normally the rash appears on the flexural body regions. Contact dermatitis (type IV) has a slow onset and tends to be erythematous, weepy, and sharply demarcated.
What test is used to evaluate type IV hypersensitivity?
Patch test to confirm contact dermatitis.
What is the defect in Burton's agammaglobulinemia? What is the inheritance?
Failure of pre-B cells to become mature B cells. Mutated tyrosine kinase. X-linked recessive disorder,
Infant boy is healthy at birth until he reaches the age of 6 months when he began to get frequent infections. His immunoglobulin levels are low. What is the diagnosis?
Bruton's agammaglobulinemia.
What is the most common immunodeficiency and what is the pathogenesis?
IgA deficiency. There is a defect in heavy chain isotype switching and patients cannot produce IgA.
Upon receiving a blood transfusion a patient shows a severe anaphylactic reaction. The boy also has a history of sinopulmonary and GI infections. Whats the diagnosis?
IgA deficiency. IgE against Fc portion of IgA heavy chain in the transfused blood.
How does common variable immunodeficiency differ from Bruton's?
Both are defects in B-cell maturation to plasma cells and associated with recurrent pyogenic infections. CVI has a late onset (25-30 yrs) and commonly follows a viral infections. CVI is also associated with an increase in autoimmune diseases.
Radiography shows an absent thymic shadow on an infant who also has severe facial abnormalities. The infant is afebrile. Labs show hypocalcemia. What is the diagnosis?
DiGeorge syndrome (catch-22). Microdeletion on q arm of chromosome 22 results in the failure of the 3rd and 4th pharyngeal pouches to develop. Congential heart abnormalities (truncus arteriosus, TOF), abnormal facial features, thymic aplasia, cleft palate, hypocalcemia (hypoparathyroidism).
Why do DiGeorge patients present with seizure like symptoms?
Hypoparathyroidism induced tetany due to hypoclacemia.
Six month old baby boy presents oral thrush, symmetric opacities on CXR, and absent tonsils. Labs show lymphopenia with normal CD20 count, but absent CD3 count. Diagnosis?
SCID.
What opportunistic infections with intracellular pathogens are common in SCID patients?
Candida albicans, P. jiroveci, Cryptococcus neoformans, Cytomegalovirus and Mycobacteria.
What is the mutation in the X-linked SCID?
Mutation in the gamma subunit of IL-2 receptor.
What is the autosomal recessive form of SCID?
Adenosine deaminase deficiency which is necessary for the breakdown of purines. dATP builds up and inhibits dNTP synthesis, thus, inhibiting DNA synthesis.
Patient presents with eczema, petechiae and infections with strep pneumoniae and h. influenzae. Labs shows small platelets. Diagnosis?
Wiskott-Aldrich syndrome. X-linked immunodeficiency disorder with eczema, recurrent infections (especially encapsulated), and thrombocytopenia with hemorrhages. F-actin assembly defect in T cells and platelets; normal IgG, decreased IgM, and increased IgA and IgE.
Patient presents with ataxia. Labs show a decrease in T-cell count, decrease IgA and an increase in serum alpha-fetoprotein. You warn the patient they are at an increase risk of lymphoma and leukemia. What is this patients disease?
Ataxia-telangiectasia. Skin and conjuctiva telangiectasia will also be present. This is an autosomal recessive disease where there is a mutation in DNA repair enzymes.
Explain how adenosine deaminase deficiency leads to SCID.
In the degradation of purines, AMP is converted to IMP or adenosine. Adenosine deaminase converts adenosine to inosine which is converted to hypoxanthine, xanthine, and then uric acid. Deficiency of adenosine deaminase builds up the levels dATP which inhibits ribonucleotide reductase, and therefore, DNA synthesis.
What primary combined immunodeficiency syndrome is characterized by absent class I and or class II MHC molecules? What are the common diseases that effect individuals with this syndrome?
Bare lymphocyte syndrome. Recurrent infections, commonly viral.
What is the classical triad of GVH disease?
Skin rash, diarrhea and hepatic dysfunction. Signs and symptoms began within 100 days of transplantation. Buld of the damage is caused by graft CTLs and their unchecked destruction of host cells. Donor T cells also activate host T cells.
What are some various mechanisms of developing autoimmunity?
Release of normally sequestered antigens: sperm.
Sharing of antigens between host and a pathogen: Rheumatic fever.
Defects in function of helper or suppressor T cells.
Persistence of autoreactive T and B cells.
Presence of specific autoantibodies.
What autoimmune disease is associated with these autoantibodies:
1) Antiacetycholine receptor
2) Anti-basement membrane
3) Anticentromere
4) Antiendomysial and antigliadin
5) Anti-insulin, anti-islet
6) Anti-IF, anti-parietal
The test sensitivity is also given:
1) Myasthenia gravis (90)
2) Goodpasture syndrome (>90)
3) CREST syndrome (90)
4) Celiac (95)
5) Type 1 diabetes (50,75)
6) Pernicious anemia (60, 90)
What autoimmune disease is associated with these autoantibodies:
1) Antimicrosomal, antithyroglobulin
2) Antiproteinase 3
3) Antiribonucleoprotein
4) Anti-thyroid-stimulating hormone
5) Antimyeloperoxidase
The test sensitivity is also given:
1) Hashimoto's thyroiditis (97, 85)
2) Wegener's granulomatosis (>90)
3) Mixed connective tissue disease (100)
4) Grave's disease (85)
5) Microscopic polyangiitis (80)
What autoimmune disease is associated with these autoantibodies:
1) Anticentromere
2) Anti-dsDNA
3) Anti-IgG (RF)
4) Antihistone
5) Antimitochondrial
1) Limited cutaneous scleroderma (CREST syndrome)
2) SLE (specific)
3) Rheumatoid arthritis
4) Drug-induced SLE
5) Primary biliary cirrhosis
What autoimmune disease is associated with these autoantibodies:
1) Anti-La and Anti-Ro
2) Antinuclear
3) Anti-Sm
4) Antismooth muscle
5) Antiphospholipid
6) Antitissue transglutaminase
7) Antitopoisomerase (Scl-70)
1) Sjogrens
2) SLE, scleroderma, dermatomyositis
3) (Sm = Smith) SLE (specific)
4) Chronic autoimmune hepatitis
5) SLE
6) Celiac
7) Diffuse cutaneous scleroderma
What is the pathogenesis of scleroderma? What three types of scleroderma are there?
Autoimmune disease wherein fibroblasts are pathologically stimulated to deposit collagen and ECM.
Localized (skin only - e.g. coup de sabre)
Limited cutaneous (CREST)
Diffuse cutaneous (high visceral involvement)
Historically what was the most common cause of death and patients with scleroderma? What is currently the most common cause?
Renal vasculature can be restricted due to collagen deposition, limiting blood flow, and activating the RAS system. Malignant hypertension and renal failure was the primary cause of death before the advent of ACE inhibitors (e.g. captopril).
Current cause of death: pulmonary fibrosis leading to cor pulmonale.
What does CREST stand for?
C: calcinosis
R: Raynauds
E: esophageal dysmotility
S: sclerodactyly
T: telangiectasia

Skin involvement usually involves distal extremities and spares the trunk.
Patient presents with xerostomia and xerophthalmia. Diagnosis?
Sjogrens disease. It is often associated with other autoimmune disease: lupus, scleroderma, or rhematoid arthritis.
Patient presents with acid reflux, dysphagia for solids, and tightened skin around the mouth. Explain the GI symptoms of this autoimmune diseased and what antibody test would confirm your diagnosis.
The patient has systemic sclerosis (scleroderma). Collagen deposition in the esophagus and destruction of the cardiac sphincter explains the GI symptoms. Anticentromere antibodies is present in 90%, while anti-topiosomerase is present in the diffuse type.
What autoimmune disease can result in complete heart block of a newborn?
SLE: IgG anti-SS-A (Ro) antibodies crossing the placenta.
What two drugs can result in drug induced-SLE?
Hydralazine: an antihypertensive vasodilator that relaxes arteriolar muscle.
Procainamide: class IA antiarrythmic, prolongs the refractory period and slow conduction (block Na).
Antihistone antibodies = drug induced-SLE
40 year old female has glomerulonephritis, inflammation in the small joints of her hand, and FEV1/FVC is slightly increased (due to a severely decreased FVC). Why may this women test positive for syphilis?
SLE patients often have anticardiolipin Abs. Anticardiolipin antibodies may produce a false positive syphilis serologic test by cross reacting with cardiolipin in the rapid plasma reagin and venereal disease test.
African american 30 year old female presents with a disciod rash, photosensitivity, oral ulcers, and hemolytic anemia. Explain what antinuclear bodies are and why this patient has them.
This patient has SLE. 95% of SLE patients will test positive for ANA (sensitive but not specific). ANA are a diverse group of autoantibodies that bind antigenic targets within the cellular nucleus.
What type of hypersensitivity is lupus nephritis?
Type III.
What is the difference between dermatomyositis and polymyositis? What similar symptoms do patients with these disease have??
Both are idiopathic inflammatory myopathies (autoimmune) characterized by symmetric proximal muscle weakness and elevated serum CK. Dermatomyositis is accompanied by skin findings such as heliotrope rash, Gottron's sign, and the shawl sign.
What is Gattron's papules pathognomic for?
Dermatomyositis.
As a clinician you should always check for what in patients with dermatomyositis or polymyositis?
You should look for an underling malignant neoplasm (present in 20% of cases).
Polymyositis is associated with T-cell mediated damage. Dermatomyositis is associated with ________ damage.
Antibody mediated.
Heliotrope eyelids is characteristic of what disease?
Dermatomyositis.
Polymyositis symptoms can be very similar to the symptoms one might get with a particular pathogen that is transmitted via pork. What is the pathogen?
Trichinella spiralis (a roundworm).
Explain the pathogenesis of Rheumatoid arthritis.
B cells produce rheumatoid factor (RF) complexes. RF complexes are IgM autoantibodies against the Fc receptor of IgG. This is a type III hypersensitivity. RF complexes activate complement which attracts neutrophils. Inflamed synovial tissue proliferates (pannus) and causes articular cartilage destruction.
What is the pathogenesis of myasthenia gravis?
Autoantibody against acetylcholine receptors (type II hypersensitivity). Interestingly, the antibody is synthesized in the thymus.