The immunocytochemical identification and characterization of indigenous dermal dendritic cells (dermal dendrocytes) using a rabbit polyclonal antibody to clotting enzyme factor XIII subunit A (FXIIIa) was carried out on normal and inflamed human cutaneous tissue. The immunophenotype of FXIIIa positive dendritic cells was analysed with a panel of 18 monoclonal antibodies using immunoperoxidase and double immunofluorescence staining techniques. The antibody against FXIIIa detected highly dendritic dermal cells located particularly in the upper reticular and papillary dermis. Double fluorescence microscopy showed that FXIIIa positive cells were bone marrow derived (HLe-I+) and co-expressed monocyte, macrophage or antigen presenting cell markers (HLA-DR+, LFA-I+, HLA-DQ+, OKM5+, Mo I+, Mono-I+, Leu M3+). No labelling was obtained with cell markers for Langerhans cells (CDI), T lymphocytes (CD2), granulocytes (LeuMI) fibroblasts (Te7), intercellular adhesion molecule-I (ICAM-I) or endothelial cells (Factor VIII related antigen). Gamma interferon induced increased expression of HLA-DR and co-expression of ICAM-I on FXIIIa+ dermal dendritic cells in normal skin in organ culture. Moreover, in benign inflammatory dermatoses such as atopic eczema and psoriasis there was an increased number of FXIIIa+, DR+, ICAM-I+ cells in the upper dermis and foci of FXIIIa+ cells in the epidermis closely associated with lymphocytes. FXIIIa positive cells in human skin represent a specific population of bone-marrow dermal dendritic cells, distinct from Langerhans cells, that share some features common to mononuclear phagocytes (monocyte/macrophages). In addition, the detection of HLA-DQ on 48% of FXIIIa+ cells and the lack of OKMI in combination with high OKM5 expression suggests an antigen-presenting cell phenotype.

Summary Background  The British Association of Dermatologists (BAD) established a web‐based pharmacovigilance register to assess the long‐term safety of biologics prescribed for patients with severe psoriasis in September 2007. The BAD Biologic Interventions Register (BADBIR) also participates in the network of European psoriasis biologics registers (Psonet). Objectives  This prospective observational cohort study compares adult patients with psoriasis treated with biologics vs. a comparator group exposed to conventional systemic therapies. Methods  Following baseline data acquisition, clinicians record changes in therapy, disease activity and adverse events for 5 years (6‐monthly for 3 years, then annually thereafter). Patient details are flagged lifelong on the National Health Service Information Centre system to capture occurrence of malignancy or death. Primary study endpoints include malignancy, infection, serious adverse events and death. Collection of long‐term effectiveness data is a subsidiary aim. Results  By November 2011, the number of dermatology centres actively recruiting across the U.K. and Republic of Ireland had risen to 108 and a further 37 were actively engaged in the set‐up process. Of the 3176 patients enrolled in the study to date, 2193 were registered within the biologic cohort and 983 in the conventional systemic (nonbiologic‐exposed) cohort. Conclusions  A robust, high‐quality, web‐based register of biologic and conventional therapy for psoriasis has been established in the U.K. This is the largest project undertaken by the BAD. The data it will provide over the coming years will be invaluable to the safe use of biologics in clinical practice. A U.K.‐wide dermatology clinical research network has been established that provides a framework for future studies in other diseases.