Gene targeting strategy for B-hIL13 mice. The exons 1-4 of mouse Il13 gene that encode the full length protein were replaced by human IL13 exons 1-4 in B-hIL13 mice.

Strain specific analysis of IL13 gene expression in wild-type C57BL/6 mice and B-hIL13 mice by RT-PCR. Mouse Il13 mRNA was detectable only in thymocytes of wild-type C57BL/6 mice (+/+). Human IL13 mRNA was detectable only in homozygous B-hIL13 mice (H/H), but not in wild-type mice

Strain specific IL13 expression analysis in homozygous B-hIL13 mice by ELISA. CD4+ T cells were collected from C57BL/6 mice (+/+) and homozygous B-hIL13 mice (H/H), and then induction of CD4+ T cells differentiation into Th2 cells, supernatant from Th2 cells culture was analyzed by ELISA with species-specific IL13 ELISA kit. Mouse Il13 was detectable in wild-type mice. Human IL13 was exclusively detectable in homozygous B-hIL13 mice but not in wild-type mice.