Diphtheria Toxin Receptor -Transgenic mice

How does the CD11c DTR system work? Is this a knock-in or is it a promoter/cDNA construct? How efficient is the deletion? How specific is the deletion for CD11c+ cells?

This was used by Divangahi et al. Eicosanoid pathways regulate adaptive immunity to Mycobacterium tuberculosis.Nature immunology, Vol. 11, No. 8. (11 August 2010), pp. 751-758