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

Platonin is a photosensitizer with NF-kappaB 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-gamma 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.