The decrease in PASI was associated with a decrease in Υδ-T cell number from 6.7 ± 4.5 to 2.7 ± 3.8 % (p = 0.05) and IL-17 expression (p > 0.05), both of which are involved in the pathogenesis of psoriasis [36]. This evidence concerns the gene IL17A and psoriasis.