Fig. 2.

Activated platelets contribute to APC activation. In parallel to the induction of apoptosis, the exposure to 8-MOP/UVA and the contact with tubing and plastics of the ECP apparatus induce changes in multiple blood components. Platelets are activated, adhere to the walls of the irradiation chamber, and express p-selecting. Extracellular ATP, IL-1β, HGMB1, and other DAMP are secreted and collectively promote monocyte differentiation into DC. A prolonged incubation in the irradiation chamber seems to promote phagocytosis of apoptotic cells and presentation of new antigens in a process referred as transimmunization.