Basic components of the immune system part 160

Jonuleit and colleagues directly compared within each of eight patients the immunogenicity of immature DCs (generated according to Nestle and colleagues in FCS-containing media using GM-CSF and IL-4) to mature DCs generated in the absence  of FCS and matured by a cocktail consisting of TNF-α, IL-1β, IL-6 and PGE2 mimicking the composition of monocyte conditioned medium. These two different DC populations were administered intranodally into opposite inguinal lymph nodes. FCS-free mature DCs induced stronger T-cell responses, both to the two recall antigens used (tetanus toxoid and PPD/tuberculin) and to tumor peptides. Interestingly, however, both immature and mature  DCs showed an expansion of peptide-specific T cells by tetramer staining; yet, only mature DCs induced IFN-γ-producing and lytic CD8 T cells. These findings suggest the interesting possibillity that the immature DCs might have induced regulatory T cells rather than effector T cells, an  observation previously noted in studies with normal volunteers