C57BL/6 mice genetically deficient in Flt3l were generated by gene targeting in the laboratory of Dr. Jacques Peschon of the Immunex Corporation in 1995. The flt3l gene was disrupted by replacing a 2.8 kb fragment containing the Flt3l exons 1 to 5 (the majority of the extracellular domain) with a PKG-neo cassette. The disrupted gene was introduced into ES cells of C57BL/6 origin, which were injected into BALB/c blastocysts. Resultant male chimeras were bred to C57BL/6 females, and offspring heterozygous for the Flt3l knockout allele were intercrossed to generate Flt3l deficient mice (Flt3l-/-). Different C57BL/6 sublines were used during the development of this strain and therefore an exact control mouse is not available. However, C57BL/6NTac mice were used as controls in the original studies. The line was transferred to the NIAID repository at Taconic in 2000 and embryo transfer derived.
McKenna HJ, Stocking JL, Miller RE, Brasel K, De Smedt T, Maraskovsky E, Maliszewski CR, Lynch DH, Smith J, Pulendran B, Roux ER, Teepe M, Lyman SD and Peschon JJ. Mice lacking flt3 ligand have deficient hematopoiesis affecting hematopoietic progenitor cells, dendritic cells, and natural killer cells. Blood 1 June 2000, 95(11) 3489-3497