Autoimmunity Flashcards
Skin Structure
What are the only cells that express MHC-II in steady-state?
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
Allergic Contact Dermatitis (type of hypersensitivity reaction)
IVa and IVd (Th1 predominant)
Key Fact: Lymphocytic infiltration and spongiosis are the predominant histologic features of contact dermatitis
Allergic Contact Dermatitis
Irritant Contact Dermatitis
Reading: Apply for 48h and then a second reading 4 to 7 days later
Top 10 Patch Test Allergen Triggers
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.
Methylisothiazolinone
Cosmetics and hair dye
Topical Corticosteroid Cross-reactivity
Key drivers of psoriasis
TNF-alpha, IL-23, and IL-17
INF-alpha is important in the early initiation of the disease
Pemphigus Vulgaris
IgG to desmoglein 3, desmoglein 1
Immunofluorescence: Epidermal IgG and C3 cell surface
Pemphigus foliaceus: Superficial bullae, erosions, scale with crusting
IgG to desmoglein 1
Immunofluorescence: Epidermal IgG and C3 cell surface
Bullous pemphigoid
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.
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