Skin-associated lymphoid tissue.

Skin-associated lymphoid tissues represents a conceptual framework on which an understanding of cutaneous immunity can be built. It is clear that regional specialization of the immune system exist, and one such specialization is represented by SALT. The skin contains, especially within the epidermis, several important types of lymphoreticular cells whose interactions with antigens and with neighboring keratinocytes lead to elaboration of antigenic signals that can be acted on by immunocompetent lymphocytes. The recirculating properties of a subset of skin-seeking T lymphocytes equips them to migrate preferentially through dermal vessels and the lymph nodes that drain the skin, creating a network of surveillance and communication that ensures that appropriate immune effectors and regulators are produced, and that threatening cutaneous pathogens are eliminated without compromise of skin function. As new experimental information is gathered concerning SALT, new insights are likely to emerge that will illuminate the immunopathogenesis of cutaneous disorders with a strong inflammatory and/or malignant component. It can be anticipated that these new insights will lead to novel therapies for the treatment and prevention of these diseases.