AbstractAlthough frequently used as implants materials, both polydimethylsiloxane (PDMS) and polytetrafluoroethylene (PTFE) are often associated with adverse effects including foreign body responses. Dendritic cells (DC) are crucial for the initiation of immune reactions and could also play a role in foreign body associated inflammations. Therefore, the interaction of DC with PDMS and PTFE was investigated regarding their capacity to induce undesired cell activation. Medical grade PDMS and PTFE films were embedded into polystyrene PS inserts via injection molding to prevent the DC from migrating below the substrate and thereby, interacting not only with the test sample but also with the culture vessel material. The viability, the expression of co-stimulatory molecules, and the cytokine/chemokine profiles were determined after 24 hours incubation of the DC with PDMS or PTFE. Blank PS inserts and tissue culture polystyrene (TCP) served as reference materials. The viability of DC was not substantially influenced after incubation with PDMS and PTFE. However, both polymers induced DC activation indicated by the upregulation of co-stimulatory molecules. The release profiles of 14 soluble inflammatory mediators showed substantial differences between PDMS, PTFE, PS, and TCP. This study showed the potential of PTFE and PDMS to activate primary human dendritic cells, which could be an explanation for the often observed inflammatory events associated with the implantation of these polymers.