The present invention relates to tolerogenic mammalian dendritic cells (DCs) and methods for the production of the tolerogenic DCs. In addition, the present invention provides a method for enhancing tolerogenicity in a host comprising administering the tolerogenic mammalian DCs of the present invention to the host. The tolerogenic DCs of the present invention comprise an oligodeoxyribonucleotide (ODN) which has one or more NF-B binding sites. The tolerogenic DCs of the present invention may further comprise a viral vector, and preferably an adenoviral vector, which does not affect the tolerogenicity of the tolerogenic DCs when present therein. Enhanced tolerogenicity in a host is useful for prolonging foreign graft survival and for treating inflammatory related diseases, such as autoimmune diseases.