The two arms of the adaptive immune response — humoral and cellular — are regulated by different subsets of dendritic cells (DCs) in humans. Humoral immunity is preferentially regulated by CD14+ dermal DCs, which produce interleukin-12 (IL-12). IL-12, in turn, acts directly on B cells and promotes the development of T follicular helper (TFH) cells. Cellular immune responses in the skin are preferentially regulated by Langerhans cells. Among the candidate mediators is IL-15. It is also possible that Langerhans cells can preferentially activate a dedicated subset of CD4+ T cells that are specialized to help CD8+ cytotoxic T lymphocytes (CTLs). Given their capacity to cross-present antigens to CD8+ T cells, CD141+ DCs might be involved in the development of CTL-mediated responses. CD141+ DCs might also be involved in the development of humoral responses through IL-12 secretion. PC, plasma cell.