• Background: SLAMF1/CD150, the founding member of the signaling lymphocyte activation molecule (SLAM) family of cell surface receptors, is broadly expressed on cells of the hematopoietic system. The differential expression pattern across distinct hematologic malignancies highlights CD150's potential as both a diagnostic biomarker and a potential prognostic indicator. Furthermore, CD150 represents a candidate target for antibody-based or measles virus-derived oncolytic therapies.
• Targeting strategy: The exons 1–4 of the mouse slamf1 gene, which encode the extracellular domain and part of the transmembrane domain, were replaced by their human counterparts in B-hSLAMF1 mice. The genomic region of mouse slamf1 gene that encodes cytoplasmic portion was retained. The promoter, 5’UTR and 3’UTR region of the mouse gene were also retained. The chimeric SLAMF1 expression was driven by endogenous mouse slamf1 promoter, while mouse slamf1 gene transcription and translation will be disrupted.  
• Validation: Human SLAMF1 protein were detected in the B-hSLAMF1 mice but not in C57BL/6JNifdc mice.
• Application: Tumor cell lines inoculated in B-hSLAMF1 mice can be used to study the in vivo efficacy and safety evaluation of antibody drugs.

Strain specific SLAMF1 expression analysis in wild-type C57BL/6JNifdc mice and homozygous humanized B-hSLAMF1 mice by flow cytometry. Splenocytes were collected from wild-type C57BL/6JNifdc mice (+/+) and homozygous B-hSLAMF1 mice (H/H) stimulated with anti-mouse CD3ε antibody (7.5 μg, i.p.) in vivo for 24 hrs (female, 6-week-old, n=1). Protein expression was analyzed with anti-mouse SLAMF1 antibody (Biolegend, 115943), and anti-human SLAMF1 antibody (Biolegend, 306307) by flow cytometry. Mouse SLAMF1 was only detectable in wild-type C57BL/6JNifdc mice. Human SLAMF1 was exclusively detectable in homozygous B-hSLAMF1 mice. The expression of m/hSLAMF in T cells were both increased after 24 hours of intraperitoneal injection of anti-mouse CD3ε antibody.

Strain specific SLAMF1 expression analysis in wild-type C57BL/6JNifdc mice and homozygous humanized B-hSLAMF1 mice by flow cytometry. Blood were collected from wild-type C57BL/6JNifdc mice (+/+) and homozygous B-hSLAMF1 mice (H/H) stimulated with anti-mouse CD3ε antibody (7.5 μg, i.p.) in vivo for 24 hrs (female, 6-week-old, n=1). Protein expression was analyzed with anti-mouse SLAMF1 antibody (Biolegend, 115943), and anti-human SLAMF1 antibody (Biolegend, 306307) by flow cytometry. Mouse SLAMF1 was only detectable in wild-type C57BL/6JNifdc mice. Human SLAMF1 was exclusively detectable in homozygous B-hSLAMF1 mice. The number of T/B cells in blood were decreased after 24 hours of intraperitoneal injection of anti-mouse CD3ε antibody.