IL17A and psoriasis: The IL‐23/IL‐17 axis is involved in the pathogenesis of several inflammatory diseases such as psoriasis, rheumatoid arthritis (RA), ankylosing spondylitis and inflammatory bowel disease.10, 11 Moreover, IL‐17, and to a lesser extent IL‐23, have been shown to contribute to iBALT formation.12 To examine the roles of the Il‐23/IL‐17 axis in the different pathologies present in BPSM1 mice, we crossed them to IL‐23p19‐13 and IL‐17A‐deficient14 mice, respectively.