DC play an important role in directing allergen-specific naïve T-cells towards a Th1, Th2 or Treg cytokine profile. The path of T cell differentiation may be due to various maturation stages and activation stimuli influencing DC/T-cell interaction. In this context, IL-10 has been shown to exhibit immune regulatory capacities and suppress both DC and T cell functions.

To further delineate effects of different culture conditions and activation stimuli on IL-10 production by DC and the consequences on DC/T-cell interactions.

BMDC were generated from hemopoietic progenitors by culture with GM-CSF or with GM-CSF plus IL-4 for 6 days and than stimulated with LPS on day 6. BMDC were phenotypically characterized by FACS analysis, and the cytokine production was measured by ELISA. DC were co-cultured with allergen-specific naive T-cells.

IL-10 production of BMDC generated with GM-CSF was strongly enhanced, compared to BMDC generated with GM-CSF plus IL-4. Co-culture of DC exhibiting increased IL-10 production with naive T-cells induced significantly less production of Th2-cytokines, like IL-5 and IL-13, whereas production of the Th1 cytokine IFN-γ as well as IL-10 was increased, compared to co-culture with DC with low IL-10 production. Vice versa, co-culture of naive T cells with BMDC characterized by low IL-10 production resulted in enhanced IL-5 and IL-13.

These data demonstrate that IL-10 production by DC may be a critical element in the regulation of T cell activation and differentiation towards an allergen-promoting phenotype. This notion may be exploited for future strategies for the prevention of allergic diseases.