The pH of the skin surface and its impact on the barrier function

The `acid mantle' of the stratum corneum seems to be important for
both permeability barrier formation and cutaneous antimicrobial
defense. However, the origin of the acidic pH, measurable on the
skin surface, remains conjectural. Passive and active influencing
factors have been proposed, e. g. eccrine and sebaceous secretions
as well as proton pumps. In recent years, numerous investigations
have been published focusing on the changes in the pH of the deeper
layers of the stratum corneum, as well as on the influence of
physiological and pathological factors. The pH of the skin follows
a sharp gradient across the stratum corneum, which is suspected to
be important in controlling enzymatic activities and skin renewal.
The skin pH is affected by a great number of endogenous factors, e.
g. skin moisture, sweat, sebum, anatomic site, genetic
predisposition and age. In addition, exogenous factors like
detergents, application of cosmetic products, occlusive dressings
as well as topical antibiotics may influence the skin pH. Changes
in the pH are reported to play a role in the pathogenesis of skin
diseases like irritant contact dermatitis, atopic dermatitis,
ichthyosis, acne vulgaris and Candida albicans infections.
Therefore, the use of skin cleansing agents, especially synthetic
detergents with a pH of about 5.5, may be of relevance in the
prevention and treatment of those skin diseases. Copyright (c) 2006
S. Karger AG, Basel