Characterization of novel, severely immunodeficient Prkdc^{Δex57/Δex57} mice

Severely immunodeficient mice are useful for understanding the pathogenesis of certain tumors and for developing therapeutic agents for such tumors. In addition, engraftment of these mice with human hematopoietic cells can yield information that helps us understand the in vivo molecular mechanisms underlying actual human viral infections. In our present research, we discovered a novel, severely immunodeficient strain of mice having a mutation in exon 57 of the Prkdc gene (Prkdc^{Δex57/Δex57}) in an inbred colony of B10.S/SgSlc mice. Those Prkdc^{Δex57/Δex57} mice showed thymic hypoplasia and lack of mature T cells and B cells in peripheral lymphoid tissues, resulting in very low levels of production of serum immunoglobulins. In addition, those mice were highly susceptible to influenza viruses due to the lack of acquired immune cells. On the other hand, since they had sufficient numbers of NK cells, they rejected tumor transplants, similarly to Prkdc^+/+ mice. Next, we generated Foxn1^nu/nuPrkdc^{Δex57/Δex57}Il2rg^-/- (NPG) mice on the BALB/cSlc background, which lack all lymphocytes such as T cells, B cells and innate lymphoid cells, including NK cells. As expected, these mice were able to undergo engraftment of human tumor cell lines. These findings suggest that Prkdc^{Δex57/Δex57} mice will be useful as a novel model of immunodeficiency, while NPG mice will be useful for xenografting of various malignancies.