Contact Sensitization Flashcards
4 types of hypersensitivity reactions
I: IgE mediated (immediate)
II: Cytotoxic/Cytolytic (IgG, IgM)
III: Immune complex-mediated
IV: T-lymphocyte mediated (delayed)
Type I hypersensitivity reaction:
IgE bound to mast cell
antigen binds–> mast cells degranulate
histamine released
Type III hypersensitivity reaction:
Immune complex activated, attracting neutrophils
products of neutrophils cause damage to tissues
In a Type IV hypersensitivity reaction, antigens are presented as
peptides on MHC molecules
T-lymphocyte activation causes ______, which generates _______
cytokine release
inflammation
T-cells release
Perforin, Protease
both eventually lead to apoptosis
In skin sensitization, chemical allergen provokes _________
Cutaneous immune response
Contact sensitization will develop if
the cutaneous immune response provoked by chemical allergen is of required magnitude
Skin sensitizing agents must be either ____ or _____
inherently protein-reactive
metabolized in skin to be protein reactive
After epidermal LC internalize and process the inducing allergen,
a proportion of LC local to site of exposure is stimulated to migrate from epidermis to lymph nodes
LC that move from skin undergo
functional maturation so they accumulate as immunostimulatory DC to present antigen effectively to responsive T lymphocytes
Antigen-driven T lymphocyte activation is characterized by
cell division/differentiation
Cellular basis for skin sensitization (immunologic memory) is represented by
selective clonal expansion of T lymphocytes
Clonal proliferation of sensitized T-cells occurs in ______, and T-cells mount reaction ________
- Lymph nodes
- after returning to epidermis
Most important determinant of acquisition of sensitization
amount of allergen per unit area of skin (rather than total amount delivered)
