The article discusses the role of dendritic cells (DCs) in mediating low-zone tolerance. It references the study "T cell killing by tolerogenic dendritic cells protects mice from allergy," by U. Luckey and colleagues in the September 1, 2011 issue of "Journal of Clinical Investigation." It says that mice's haptenrestimulated lymph node cells exposed to low-zone tolerance before hapten sensitization had higher tumour necrosis factor (TNF) levels.