Gene targeting strategy for B-hCD40/hFcRn mice.
The exons 2-7 of mouse Cd40 gene that encode the extracellular sequence were replaced by human CD40 exons 2-7 in B-hCD40/hFcRn mice. The human full-length FCGRT cDNA sequence was inserted in the Fcgrt exons 2-4 in B-hCD40/hFcRn mice.

Strain specific analysis of CD40 expression in homozygous B-hCD40/hFcRn mice by flow cytometry. Splenocytes were collected from C57BL/6 mice (+/+;+/+) and homozygous B-hCD40/hFcRn mice (H/H;H/H), and analyzed by flow cytometry with species-specific anti-CD40 antibody. Mouse CD40 was detectable in wild-type mice. Human CD40 was exclusively detectable in homozygous B-hCD40/hFcRn mice but not in wild-type mice.

Strain specific analysis of FcRn expression in homozygous B-hCD40/hFcRn mice by western blot.Liver was collected from C57BL/6 mice (+/+;+/+) and homozygous B-hCD40/hFcRn mice (H/H;H/H) and analyzed by western blot with species-specific anti-FcRn antibody. Mouse FcRn was detectable in wild-type mice. Human FcRn was detectable only in homozygous B-hCD40/hFcRn mice but not in wild-type mice.

The study evaluated the pharmacokinetic characteristics of anti-human CD40 antibodies in B-hCD40/hFcRn mice. C57BL/6 mice, B-hFcRn mice, and B-hCD40/hFcRn mice were treated with YH015 or YH003 (anti-human CD40 antibodies) (n=6). Blood samples were collected at different time points for the pharmacokinetic (PK) assay. Compared to wild-type mice and B-hFcRn mice, B-hCD40/hFcRn mice can more accurately reflect the in vivo concentration changes of anti-human CD40 antibodies, the results showed that B-hCD40/hFcRn mice can be used to evaluate the pharmacokinetics of anti-human CD40 antibodies in vivo.