Normal chicken serum

Frozen skin sections from non-lesional and lesional psoriasis patients were fixed with acetone and blocked in 10% normal chicken serum (Vector Laboratories) for 30 minutes. Primary antibodies for C/EBPβ and HBD2 (Table S2) were incubated overnight at 4°C and amplified with the appropriate secondary antibody goat anti-mouse IgG1 conjugated to Alexa Fluor 488 and chicken anti-goat Alexa Flour 594 (Invitrogen, Eugene, OR) respectively, for 30 minutes.
IF images were acquired using the appropriate filters of a Zeiss Axioplan 2 wide-field fluorescence microscope (Thornwood, NY) with a Plan Neofluar 20×0.7 numerical aperture lens and a Hamamatsu Orca Er-cooled charge-coupled device camera (Bridgewater, NJ), controlled by the METAVUE software (MDS Analytical Technologies, Downington, PA). Images in each figure are presented both as single-color stains (green and red) located above the merged image, so that localization of two markers on similar or different cells can be appreciated. Cells that co-express the two markers in a similar location are yellow in color. A white line denotes the dermoepidermal junction. Dermal collagen fibers gave green autofluorescence, and antibodies conjugated with a fluorochrome often gave background epidermal fluorescence.

The following reagents and chemicals were obtained from Sigma-Aldrich (St. Louis, MO, USA): paraformaldehyde solution, radioimmunoprecipitation assay (RIPA) buffer, sucrose, Triton X-100, skim milk powder, 4′,6-diamidino-2-phenylindole (DAPI). Normal chicken serum was purchased from Vector laboratories (Burlingame, CA, USA). The other reagents were obtained from the following vendors: 5-HT, tryptophan hydroxylase 2 (TPH2), cAMP response element-binding (CREB), phospho-CREB, BDNF, beta-actin antibodies, and horseradish peroxidase (HRP)-conjugated horseradish peroxidase secondary antibody for western blotting (Abcam, Cambridge, MA, USA; and Santa Cruz Biotechnology, Santa Cruz, CA, USA).