Platonin modulates differentiation and maturation of human monocyte-derived dendritic cells

Platonin is a photosensitizer with NF-κB inhibitory activity that activates macrophages and suppresses lymphocyte response. In this study, we tested the effect of platonin on differentiation and maturation of human myeloid dendritic cells (DC) from CD14+ monocytes. Triggering of DC differentiation by GM-CSF and IL-4 resulted in typical immature DCs that were further stimulated to maturation by combination of cytokines. When platonin (2 to 50 ng/mL) was added to the culture, the resulting DCs had thicker and blunter protruding projections, lower CD83 expression, greater CD80 expression, and less stimulatory activity on allogeneic naive CD4+CD45RA+ T cells in terms of their proliferation and interferon-γ production. This suggests that platonin redirects DC differentiation toward an intermediate stage of maturation, whereby the DCs have uniquely enhanced expression of CD80 which may confer some degree of immune tolerance.