Plasmacytoid dendritic cells: in vivo regulators of alloimmune reactivity?

Dendritic cells (DC) exhibit remarkable plasticity in terms of their ability to induce and regulate innate and adaptive immune responses. Human and mouse interferon alpha-producing plasmacytoid (p) DC have been found to regulate allogeneic T cell responses in vitro. Evidence is emerging that pDC may also regulate immune reactivity in vivo, including the responses that underlie graft-versus-host disease and organ transplant rejection. These cells may also offer potential for therapy of adverse immune responses and the promotion of tolerance induction.