“…The knowledge that DC-derived cytokines are key components in driving T-cell responses has been complemented by studies demonstrating that the interaction of DC and T cells is modulated by multiple factors (Mahnke and Enk, 2005). For example, the strength of stimulation, as determined by the antigen dose and co-stimulation, genetic background, tissuederived factors, and specific cytokines produced after encounter with pathogen-derived products play an important role in determining whether a Th1 or Th2 response develops (Boonstra et al, 2006). The proposed concept that specific DC populations are predetermined in promoting Th responses (Maldonado-Lopez et al, 1999;Pulendran et al, 1999;Moser and Murphy, 2000) has been challenged by a number of studies demonstrating that each DC subset exhibits a considerable plasticity in its T-cell differentiation capacity (Reis e Sousa, 2001;MacDonald et al, 2001;d'Ostiani et al, 2000).…”