IL17A and psoriasis: [12], [21] Although earlier reports suggested that IL-22 was co-expressed with IL-17, our data showed that only 31%–41% of the IL-22 positive CD4+T cells also expressed IL-17. These results revealed that, besides Th17, a large proportion of IL-22 is produced by other Th subtypes. These other subtypes may also be involved in BD pathogenesis, which is similar to observations found in patients with psoriasis [8].