It has been found that dendritic cells can be prepared which cannot mature. These cells can provide signal (1) to T cells but cannot provide co-stimulatory signal (2). T cells which are stimulated by the permanently immature dendritic cells therefore anergise, so the dendritic cells are tolerogenic rather than immunogenic. The cells are generally CD40<-ve>, CD80<-ve> and CD86<-ve>, and remain so when stimulated by inflammatory mediators such as lipopolysaccharide. The cells can be prepared conveniently by the culturing adherent embryonic stem cells in the presence of GM-CSF.
