 The primary function of HLA-DR is to present peptide antigens, potentially foreign in origin, to the immune system for the purpose of eliciting or suppressing T-(helper)-cell responses that eventually lead to the production of antibodies against the same peptide antigen.Antigen presenting cells (macrophages, B-cells and dendritic cells) are the cells in which DR are typically found.Increased abundance of DR 'antigen' on the cell surface is often in response to stimulation, and, therefore, DR is also a marker for immune stimulation.