Background: Trafficking of dendritic cell (DC) subtypes to and from the skin plays a pivotal role in atopic dermatitis (AD).
Objectives: We sought to determine the CCR pattern of epidermal DC subtypes and CCL expression in relation to the state of AD.
Methods: Shave biopsy specimens were taken from patients with AD before and after 24 and 72 hours of atopy patch testing and from the skin of patients with chronic AD, skin of patients with psoriasis, and healthy skin. CCR expression of epidermal DCs was studied by using flow cytometry, and chemokine mRNA levels in the skin were quantified by means of real-time PCR.
Results: The total number of CD1a(+) epidermal DCs increased and the proportion of Langerin-positive CD1a(+) DCs decreased whereas the percentage of Langerin-negative CD1a(+) DCs increased after allergen application. Expression of CCR5 and CCR6 of Langerin-negative CD1a(+) DCs was characteristic for acute AD. Expression of CCL1, CCL3, CCL4, and CCL11 mRNA was greater in patients with acute AD versus that seen in patients with chronic AD. Only a strong increase of CCLs, in particular CCL1, CCL17, and CCL18, went along with eczema development, and increased CCL1, CCL13, CCL17 and CCL18 expression was specific for patients with chronic AD compared with those with psoriasis.
Conclusion: Modified recruitment and differentiation of DCs from their dermal and blood precursors occurs in the acute phase of AD. A boost in the amplitude of CCLs after allergen application goes along with eczema development.