We have previously shown that the injection of antigen-pulsed DC induces the synthesis of specific IgGI and IgG2a antibodies, whereas macrophages favor the production of IgG 1 and IgE antibodies specific for the antigen. These data indicate that the isotype and the amplitude of the B cell response can be regulated by the nature of the APC, suggesting that Th cell differentiation is controlled at the level of antigen presentation1,2. In this report, we directly evaluate Thl and Th2 functions in lymph nodes of mice that were immunized by injection of dendritic cells or peritoneal macrophages pulsed with the antigen. We show that macrophages induce Th2 differentiation in vivo, whereas DC drive the development of cells able to secrete Thl and Th2-derived cytokines.
