Contact Sensitization Lec 5

Question 1

Where is sensitization based?

Answer 1

T-cells

Question 2

Types of hypersensitivity reactions

Answer 2

mediated reactions (immediate), cytotoxyc/cytolytic, immune-complex mediated, and lymphocyte-mediated reactions (delayed-type)

Question 3

What are lymphocyte-mediated reactions?

Answer 3

Most common form with cosmetic products. Antigens are presented as peptides on MHC molecules. T lymphocytes are activated after recognition of their specific antigen. This causes release of cytokines, which generates inflammation. T cells are cytotoxic and cause tissue damage.

Question 4

Definition of skin sensitization

Answer 4

An immunological process whereby heightened responsiveness to a chemical allergen is induced. This happens when a susceptible individual is exposed topically to inducing chemical allergen.

Question 5

Allergen/Hapten transcellular route

Answer 5

passes alternately into the keratin-packed corneocytes and the lipid-rich extracellular region by partitioning into and out of the keratinocyte cell membranes

Question 6

Allergen/Hapten intercellular route

Answer 6

chemical passes around the corneocytes in the lipid rich extracellular lamellar regions

Question 7

Allergen/Hapten appendageal route

Answer 7

chemical by-passes the corneocytes and lipid lamellae by entering the shunts provided by the hair follicles, sweat glands and sebaceous glands. Bypass necessity to penetrate the SC

Question 8

Function of Langerhan’s cells

Answer 8

Presents antigen to the immune system

Question 9

Contact Sensitization in a nutshell

Answer 9

Small molecules penetrate and bind to proteins. Hapten-protein complexes are recognized by langerhan’s cells. Move to lymph nodes and stimulate clonal proliferation of sensitized T-cells. T-cells return to epidermis to mount reaction. Upon any further exposure to the allergen, sensitized T-cells again return to epidermis to mount another reaction.

Question 10

Potency

Answer 10

the amount of test chemical required to cause sensitization or to induce a certain magnitude of response linked casually and quantitatively with the acquisition of skin sensitization.

Question 11

Phases of HRIPT

Answer 11

induction (afferent) phase, elicitation (effector) phase.

Question 12

Induction phase

Answer 12

Lasts through skin, lymph nodes and until the T-cells are sensitized.

Question 13

Elicitation phase

Answer 13

When the t-cells are sensitized until the reaction is seen on the skin.