Distinctive dendritic cell subsets expressing factor XIIIa, CD1a, CD1b and CD1c in mycosis fungoides and psoriasis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73825/1/j.1600-0560.1995.tb00742.x.pd

Activin A Induces Langerhans Cell Differentiation In Vitro and in Human Skin Explants

Langerhans cells (LC) represent a well characterized subset of dendritic cells located in the epidermis of skin and mucosae. In vivo, they originate from resident and blood-borne precursors in the presence of keratinocyte-derived TGFβ. Ιn vitro, LC can be generated from monocytes in the presence of GM-CSF, IL-4 and TGFβ. However, the signals that induce LC during an inflammatory reaction are not fully investigated. Here we report that Activin A, a TGFβ family member induced by pro-inflammatory cytokines and involved in skin morphogenesis and wound healing, induces the differentiation of human monocytes into LC in the absence of TGFβ. Activin A-induced LC are Langerin+, Birbeck granules+, E-cadherin+, CLA+ and CCR6+ and possess typical APC functions. In human skin explants, intradermal injection of Activin A increased the number of CD1a+ and Langerin+ cells in both the epidermis and dermis by promoting the differentiation of resident precursor cells. High levels of Activin A were present in the upper epidermal layers and in the dermis of Lichen Planus biopsies in association with a marked infiltration of CD1a+ and Langerin+ cells. This study reports that Activin A induces the differentiation of circulating CD14+ cells into LC. Since Activin A is abundantly produced during inflammatory conditions which are also characterized by increased numbers of LC, we propose that this cytokine represents a new pathway, alternative to TGFβ, responsible for LC differentiation during inflammatory/autoimmune conditions

Denileukin diftitox for the treatment of CD25 low-expression mycosis fungoides and Sezary syndrome

In a placebo-controlled study, denileukin diftitox (DD) was effective against cutaneous T-cell lymphoma (CTCL) expressing CD25. An open-label companion study examined the efficacy and safety of DD in 36 patients with skin biopsies containing 487 days, and median time to treatment failure was 68.5 days. No difference in PFS by disease stage was observed. The safety profile of DD in CD25 low-expression disease was similar to that in CD25+ disease. These findings suggest that CD25 low expression does not preclude a meaningful clinical response to DD in patients with CTCL