Loading of Dendritic Cells with Antigen in Vitro Or in Vivo by Immunotargeting can Replace the Need for Adjuvant

Abstract

The discovery that T cells are activated upon recognition of antigen presented by MHC products has focused the attention on the major role of antigen-presenting cells in the initiation of immune responses. Although several cell populations can display peptides in association with class II antigens, only dendritic cells appear to efficiently activate specific, naive T cells. Recent studies have shown that antigen presentation and T cell sensitization are independently regulated in dendritic cells, and this specialization of function supports the idea that, among the heterogeneous population of APC, they may be the most efficient cells to present an antigen and to sensitize T cells in vivo. In this report, we show that a single injection of DC appropriately pulsed in vitro with soluble protein antigens activates a strong specific humoral response in vivo. Moreover, antigen targeted on dendritic cells in vivo by the use of antibodies induces the secretion of antigen-specific antibodies in the absence of adjuvant.