Autoimmunity Flashcards

1
Q

Skin Structure

A
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2
Q

What are the only cells that express MHC-II in steady-state?

A

Langerhans cells

Required for adaptive immune response in the epidermis, 2-4% of epidermal cells.

Under inflammatory conditions they are repopulated by BM-derived monocytes: Phagocytosis, express high-affinity IgE receptor, IL-1b, and TNF facilitate migration to draining LN, can present Ag to T cells in LN as well as intracutaneously

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3
Q

Allergic Contact Dermatitis (type of hypersensitivity reaction)

A

IVa and IVd (Th1 predominant)

Key Fact: Lymphocytic infiltration and spongiosis are the predominant histologic features of contact dermatitis

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4
Q
A

Allergic Contact Dermatitis

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5
Q
A

Irritant Contact Dermatitis

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6
Q
A

Reading: Apply for 48h and then a second reading 4 to 7 days later

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7
Q

Top 10 Patch Test Allergen Triggers

A
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8
Q
A

Toxicodendron dermatitis (poison ivy [Anacardiaceae], poison oak, poison sumac)

The most common form of ACD. Caused by: urushiol and oleoresin (found in the sap and oozes readily from any crushed part of the plant).

Key Fact: Cross-reactivity with mango peel.

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9
Q

Methylisothiazolinone

A

Cosmetics and hair dye

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10
Q

Topical Corticosteroid Cross-reactivity

A
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11
Q

Key drivers of psoriasis

A

TNF-alpha, IL-23, and IL-17

INF-alpha is important in the early initiation of the disease

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12
Q

Pemphigus Vulgaris

A

IgG to desmoglein 3, desmoglein 1

Immunofluorescence: Epidermal IgG and C3 cell surface

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13
Q
A

Pemphigus foliaceus: Superficial bullae, erosions, scale with crusting

IgG to desmoglein 1

Immunofluorescence: Epidermal IgG and C3 cell surface

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14
Q

Bullous pemphigoid

A

IgG to BPAG2, BPAG1, BP-180, hemidesmosome, lamina lucida

Immunofluorescence: Linear basement membrane zone IgG and C3

Key Fact: tense bullae on a hive base, itchy.

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15
Q
A

Epidermolysis Bullosa Aquisita (EBA)

  • Tense bullae oral mucosa/areas of trauma
  • IgG to Type VII Collagen, anchoring fibrils
  • Immunofluorescence: Linear basement membrane zone IgG and C3, +/- linear IgA/IgM
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16
Q
A

Pemphigoid (linear basement membrane zone IgG and C3)

  • Subepidermal bullae; eosinophil infiltrate in the upper dermis
  • Serum studies: ELISA for BP180, NC16A, BP230, NC1 7NC2 domains of type 7 collagen, 70% have elevated IgE, peripheral eosinophilia
17
Q
A

Pemphigus

Immunofluorescence: Epidermal IgG and C3 cell surface

Serum studies: Sensitivity of anti-Dsg ELISA 96%, specificity 100%; titers fluctuate with the level of disease activity

18
Q

IgG4- Related Disease (IgG4-RD)

A

Classically presents with autoimmune pancreatitis, but can manifest in any organ system

Diagnostic Criteria: Swelling in single or multiple organs. elevated serum IgG4 >135mg/dL, biopsy with histopathology demonstrating marked lymphocyte and plasma cell infiltrate and fibrosis and infiltration of IgG4 plasma cells >40% and >10/HPF

Dermatologic Manifestations: Papules, Plaques +/- Nodules, pruritus, typically involves head and neck

Treatments: Systemic/Topical steroid, rituximab, azathioprine, methotrexate

19
Q

Felty’s Syndrome

A

(+) RF, neutropenia, splenomegaly

20
Q

TNF inhibitors

(agents and side effects)

A

Side effects:

  • Increased risk of bacterial and fungal infections
  • Reactivation of latent TB (screening important)
  • Drug-induced lupus
  • Neurologic deficits
  • Cardiac failure (avoid in patients with low EF)
  • Possible increase in lymphoma
21
Q

Jaccoud’s

A

Non-erosive polyarthropathy (SLE)

22
Q

What is the most common finding in the renal biopsy of a patient with SLE?

A

“Full-house” immunofluorescence (IgG, IgA, IgM, C3, C1q)

23
Q

Autoantibodies in SLE

A
24
Q

SLE poor prognosis (50% mortality in 10 years)

A
  1. Elevated creatinine, hypertension, nephrotic syndrome
  2. Anemia, hypoalbuminemia, hypocomplementemia
  3. Male sex
  4. Ethnicity
25
Q
A

Dermatomyositis

  1. Calcinosis
  2. Purple discoloration on eyelids (heliotrope rash)
  3. Back and shoulders (shawl sign) / Neck (V sign)
  4. Violaceous papules on knuckles (Gottron’s sign)
26
Q

Antisynthetase syndrome

A
  • Myositis
  • Arthritis
  • Obstructive lung disease
  • Cracked, furrowed skin (Mechanics hands)
27
Q

Scleroderma (antibodies)

A
28
Q

Nomenclature of Primary Vasculitis

A
29
Q

Granulomatosis with Polyangiitis

A

PR3-cANCA 75-90%

30
Q

Microscopic Polyangiitis

A

MPO-pANCA 50-80%

31
Q

Eosinophilic Granulomatosis With Polyangiitis

A

ANCA associated with ~40% of patients usually pANCA (anti-MPO)

Diagnosis often based on clinical features: asthma, hypereosinophilia, clinical manifestations consistent with vasculitis.

Phases:

  1. Prodromal (asthma, allergic rhinitis)
  2. Eosinophilic (peripheral eosinophilia, eosinophilic tissue infiltrates)
  3. Vasculitis (nerve, skin, lung, GI tract, heart)
32
Q
A