Loss of Hhex results in progressive lymphopenia. (A) Effective deletion of Hhex in hematopoietic tissues of Hhex^−/Δ mice. One month after poly(I:C) treatment, genomic DNA was prepared from the BM, spleen, and thymus of mice of the indicated genotypes and PCR was performed to detect floxed (top), wild-type (middle), and deleted (bottom) Hhex alleles. Lanes represent individual mice analyzed. (B) Time course analysis of blood parameters after Hhex deletion. Numbers of mice analyzed are shown in parentheses. (C) Time course analysis of leukocyte populations after Hhex deletion. Absolute numbers of each leukocyte population were determined by combining white blood cell counts with flow cytometric data. *P < .05; **P < .01 by Student t test. (D) Mx-Hhex mice were treated with poly(I:C) at 7 weeks of age. Then 9 to 11 months later, genomic DNA was prepared from peripheral leukocytes of the indicated lineages and PCR was performed as it was in (A). Lanes represent individual mice analyzed.