Transgenic mice were created that contain a DNA fragment containing 3717 bp of sequence upstream from the transcription start site of the mouse Epx gene (formerly EPO) as well as the first 54 bp encoding the 5'-untranslated region of the Epx mRNA followed by the open reading frame encoding the Diphtheria Toxin A chain. The DTA expression construct was completed with the addition of a series of exons-introns derived from a 2.1kb fragment encoding a truncated portion of the human growth hormone gene downstream of the DTA open reading frame. Analysis of circulating leukocytes demonstrated that transgenic animals were devoid of eosinophils but otherwise have a full complement of hematopoietically derived cells. (J:92831)