CXCL13 and pemphigus: This also increases the co-stimulatory molecule levels of DCs in TLSs.134,135 Additionally, Treg cells appear to promote TLS formation, although the mechanism may be indirect.136 In the skin TLSs of patients with pemphigus, Treg cells directly contact Th1-like CD4+ T cells, which promotes CXCL13 production.137