CONCISE COMMUNICATION BJD British Journal of Dermatology Guttate psoriasis is associated with an intermediate phenotype of impaired Langerhans cell migration L.H. Eaton, 1 L. Chularojanamontri, 2,3 F.R. Ali, 2 E. Theodorakopoulou, 2 R.J. Dearman, 1 I. Kimber 1 and C.E.M. Griffiths 2 1 Faculty of Life Sciences and 2 The Dermatology Centre, Salford Royal Hospital, University of Manchester, Manchester Academic Health Science Centre, Manchester, U.K. 3 Department of Dermatology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand Correspondence Laura H. Eaton. E-mail: laura.eaton@manchester.ac.uk Accepted for publication 6 March 2014 Funding sources This study was funded by Janssen Pharmaceutical Research & Development, LLC. Conflicts of interest C.E.M.G. has received consulting and lecture fees and/or research grants from Abbvie, Actelion, Incyte, Janssen-Cilag, LEO Pharma, Novartis, Pfizer, Sandoz, MSD and Trident, all of whom manufacture products either in trial or in use for the management of psoriasis. I.K. and R.J.D. receive research support from Novartis. L.H.E. and L.C. contributed equally to this article. DOI 10.1111/bjd.12960 Summary Background An episode of guttate psoriasis can be an isolated event, can recur as guttate episodes, or develop into chronic plaque psoriasis (CPP). A previous study revealed that early-onset (before age 40 years) CPP is associated with inhi- bition of epidermal Langerhans cell (LC) migration. Objectives To determine whether guttate psoriasis is also associated with abnormal LC mobilization. Methods Three groups of patients were recruited: current guttate episode (n = 5); guttate psoriasis progressed to CPP (n = 6); and resolved guttate psoriasis (n = 2). Biopsies were taken from uninvolved skin and LC migration was mea- sured ex vivo using an epidermal explant model. Results Patients with a current episode of guttate psoriasis displayed epidermal LC migration, although the extent was significantly lower than in skin from healthy controls (P < 0Á05). In contrast, in those patients in whom guttate psoriasis developed into CPP there was no mobilization of LC. Finally, in patients in whom guttate psoriasis had resolved, LC migration was normal. Conclusions We have shown that guttate psoriasis is associated with an abnormality of LC mobilization, but a less marked inhibition compared with that seen in CPP. In resolved guttate psoriasis LC function returns to normal. These data provide further evidence that the pathogenesis of psoriasis is characterized by significant changes in epidermal LC function. What’s already known about this topic? • Guttate psoriasis can either resolve or progress to chronic plaque psoriasis (CPP). • Patients with CPP have impaired epidermal Langerhans cell (LC) migration. What does this study add? • LC migration occurs in guttate psoriasis, thereby differentiating it from CPP, but at a lower level than in healthy individuals, and is restored upon clearance. • These data provide insights not only into the mechanisms of LC mobilization, but also into factors that determine the resolution of psoriasis. Langerhans cells (LC), a population of epidermal dendritic cells that present antigens to T lymphocytes and orchestrate cutaneous immune responses, have been implicated in the pathogenesis of psoriasis. 1–4 In normal skin the mobilization of LC requires signals from interleukin (IL)-1b and tumour necrosis factor (TNF)-a. In previous investigations we have shown that early-onset (presenting before age 40 years) chronic plaque psoriasis (CPP) is associated with a substantial inhibition of LC migration in response to IL-1b and TNF-a. 2 The view is that the impairment of LC mobilization is the consequence of abnormalities in the epidermal microenviron- ment. 3 Guttate psoriasis can be an isolated event that resolves fully, recurs as repeated guttate episodes or, in approximately one- © 2014 British Association of Dermatologists British Journal of Dermatology (2014) 171, pp409–411 409