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Differential hypermelanosis induced by allergic contact dermatitis
The Journal of Investigative Dermatology
|December 1, 1987
Summary
Allergic contact dermatitis can cause skin hyperpigmentation, similar to human conditions. Certain allergens stimulate melanocytes and melanophages, unlike UV radiation, indicating unique pigmentary mechanisms.
Area of Science:
- Dermatology
- Immunology
- Pigmentation Biology
Background:
- UVB, PUVA, and allergic contact dermatitis (ACD) induce hyperpigmentation in guinea pig skin.
- ACD-induced pigmentary changes resemble those in Mongoloid human skin.
Purpose of the Study:
- To investigate the mechanisms of allergen-induced hyperpigmentation.
- To compare the effects of six different allergens on skin pigmentation.
Main Methods:
- Induced allergic contact dermatitis using six allergens: dinitrochlorobenzene (DNCB), 1-phenylazo-2-naphthol (PAN), benzyl salicylate (BS), jasmine oil (JO), hydroxycitronella (HC), and ylang ylang oil (YYO).
- Assessed visible hyperpigmentation, melanocyte populations (dopa-positive), and melanophage counts in the dermis.
- Evaluated primary irritant reactions with 100% JO in non-sensitized animals.
Main Results:
- PAN, JO, HC, and YYO induced visible hyperpigmentation, peaking around 40 days post-induction.
- Hyperpigmentation correlated with increased dopa-positive melanocytes.
- Increased melanophages observed in PAN, YYO, and HC induced hyperpigmentation, notably in PAN.
- BS and DNCB allergies, and JO irritation, did not cause significant hyperpigmentation or melanophage increase.
Conclusions:
- Allergic contact dermatitis acts as a unique melanogenic stimulant, distinct from UV irradiation.
- The presence and activity of melanophages are crucial for allergen-induced hyperpigmentation.
- Different allergens elicit varying pigmentary responses, highlighting specific immunological pathways.