Standard protocols for the generation of murine dendritic cells (DCs) employ medium supplemented with heat-inactivated fetal
calf serum (FCS). Recently, several attempts have been made to avoid serum exposure during DC culture. The impetus for these
efforts has been a desire to generate DCs for clinical use, as preclinical data have demonstrated their efficacy in immune activation
and in immune suppression both in vitro and in vivo. However, these protocols have resulted in contradictory outcomes with
respect to DC survival in culture and activation status. In this report, we compared several serum-free culture conditions with
respect to survival, differentiation, activation, and cytokine profile of murine DC progenitors. DC progenitors can survive only in
some serum-free conditions. Surprisingly, DCs grown in serum-free medium display a higher expression of activation markers
upon stimulation. They produce increased IL-12 and decreased IL-6 following stimulation. Furthermore, DCs derived under serumfree
conditions may express unusual surface markers, B220 and Ly6C/G, implying an increased differentiation to plasmacytoid
DCs (pDCs).