Abstract: Methods for the treatment of skin disorders, including psoriasis, atopic dermatitis, allergic contact dermatitis, alopecia areata and skin cancers are provided, such methods comprising administering multiple doses of a composition having antigenic and/or adjuvant properties. Compositions which may be usefully employed in the inventive methods include inactivated M. vaccae cells, delipidated and deglycolipidated M. vaccae cells, M. vaccae culture filtrate and compounds present in or derived therefrom, together with combinations of such compositions.