IDO1 and psoriasis: Reflecting the decreased DC numbers by systemic IL-17A blockade, total skin transcriptome of T17 cell-stimulating DCs (IL23A) (3) and mature DCs (LAMP3 (DC-LAMP), CD274 (PD-L1) and IDO1) (16, 33, 34) were decreased in posttreatment psoriasis lesional skin compared to pretreatment psoriasis lesional skin in both microarray and RT-PCR experiments (Figures 2B, C, p < 0.05).