Innate and adaptive immunity

Abstract

The skin immune system is the complex network of cells that are able to mount an immune response in the skin. The immune response can be divided into innate and adaptive arms. This is highly relevant to both systemic immunity, as well as immunity in the skin. The innate immune system responds rapidly to microbial insults, but is thought to have no memory or specificity. The adaptive immune system, composed of B lymphocytes and T lymphocytes, requires more time to respond to a threatening challenge to the host, but is responsible for long-lasting memory and specificity, and the development of an effector pool of lymphocytes for humoral or cell mediated immunity. Virtually all cells that reside in the skin play some role in the function of the skin immune system. Resident cells, such as keratinocytes, and bone marrow-derived cells, such as Langerhans' cells, monocytes, and macrophages, are critical. There are a number of cells that can migrate into the skin as well (e.g., T cells, neutrophils) that also play a critical role. In addition to the cellular components of the skin immune system, soluble mediators are quite important. Cytokines, chemokines, lipid mediators, and antimicrobial peptides are examples of some of the critical components of the secreted mediators that can mobilize immunocytes to migrate into skin or mediate a protective or pathogenic inflammatory response. © 2008 Springer London.