Exogenous topical lactoferrin inhibits allergen-induced Langerhans cell migration and cutaneous inflammation in humans

Background: Lactoferrin (LF), an iron-binding protein found in exocrine secretions, is known to possess antibacterial properties. It has recently been proposed that LF may also influence inflammatory reactions. Objectives: To characterize in humans the ability of recombinant homologous LF to inhibit the induced migration of epidermal Langerhans cells (LCs) from the skin, a process known to be dependent upon the proinflammatory cytokines tumour necrosis factor (TNF)-α and interleukin 1β and to influence cutaneous inflammatory reactions. Methods: We investigated the anti-inflammatory properties of LF in human volunteers. Results: Topical exposure to LF 2 h prior to sensitization caused a significant reduction in contact allergen (diphenylcyclopropenone, DPC)-induced LC migration from the epidermis as judged by the altered frequency of cells expressing either HLA-DR or CD1a determinants. That this reduction was secondary to an inhibition of TNF-α production was indicated by the fact that LF failed to influence LC migration induced by intradermal injection of this cytokine. In approximately 50% of those volunteers who displayed local inflammation in response to DPC, LF was found to cause a discernible reduction in the clinical severity of the reaction, associated with reduced infiltration of inflammatory cells. Conclusions: These data demonstrate that LF is able to influence cutaneous immune and inflammatory responses, possibly because of an impaired production of local proinflammatory cytokines.