Processing of Antigens by Dendritic Cells: Nature’s Adjuvant

Abstract

These are exciting times in dendritic cell biology. For example, scientists are learning to control dendritic cell development to produce large numbers of these specialized antigen-presenting cells. The dendritic cells are then used in studies of mechanism of action, e.g., antigen uptake and processing. The findings also are being exploited in clinical studies where antigen-pulsed dendritic cells are being administered to initiate immunity in humans, especially resistance to tumors. Of recent interest is the capacity of dendritic cells to process antigens from dying cells. Dendritic cells process antigens from apoptotic cells to produce MHC class I-peptide complexes, and also process either apoptotic or necrotic cells to produce MHC class II-peptide complexes. The efficacy of antigen presentation by dendritic cells can be studied with standard T-cell stimulation assays or with monoclonal antibodies that directly identify specific MHC-peptide complexes. We have used antibodies to show that dendritic cells efficiently present peptides from dying cells. Dendritic cells also express high levels of costimulatory molecules (e.g., CD40, CD86) for T-cell stimulation, and select chemokine receptors (e.g., CCR7) that guide the dendritic cells to the T-cell areas of lymphoid organs.