Epidermal Langerhans Cell Migration: Signals and Mechanisms

Abstract

Following skin sensitization a proportion of local Langerhans cells (LC) are stimulated to migrate from the epidermis via afferent lymphatics to draining lymph nodes¹. We have reported recently that tumour necrosis factor α (TNF-α), a keratinocyte-derived cytokine, may be an important mediator of this process and have proposed that the induced production, or increased production, of TNF-α by keratinocytes in response to skin sensitization might provide an initial stimulus for the movement of LC from the epidermis^2,3. In support of this is the demonstration that keratinocyte mRNA for TNF-α is upregulated following topical exposure of mice to skinsensitizing chemicals⁴. To investigate further the requirement for TNF-α in the movement of LC from the skin to draining lymph nodes we have examined the influence of a neutralizing anti-TNF-α antibody on this process.