Gene targeting strategy for B-hKIT mice. A chimeric coding sequences of human KIT gene encoding the extracellular region and mouse Kit gene encoding the signal peptide, transmembrane region and the intracellular region were inserted in exon 2 of mouse Kit gene in B-hKIT mice.

Strain specific KIT expression analysis in homozygous B-hKIT mice by flow cytometry. Bone marrow were collected from wild-type mice (+/+) and homozygous B-hKIT mice (H/H), and analyzed by flow cytometry with species-specific anti-KIT antibody. Mouse KIT was detectable in wild-type mice. Human KIT was exclusively detectable in homozygous B-hKIT mice but not in wild-type mice.

Effects of C48/80‑induced systemic anaphylaxis reaction. (A) Anti‑hKIT antibody briquilimab (25 mpk, commercially purchased) was injected before challenge at week 0. B‑hKIT mice (H/H) (n=3) were challenged with C48/80 at week 1. (B) Body temperature was recorded from 0 to 90 minutes after challenge with 2.5 mg/kg C48/80. Briquilimab, by depleting mast cells, attenuated the decrease in body temperature induced by C48/80, demonstrating its inhibitory effect on the systemic anaphylaxis reaction in B‑hKIT mice.