Cx₄Mab-1: A Novel Anti-Mouse CXCR4 Monoclonal Antibody for Flow Cytometry

The CXC chemokine receptor 4 (CXCR4, CD184) is a member of the G protein-coupled receptor family that is expressed in most leukocytes. Overexpression of CXCR4 is associated with poor prognosis in not only hematopoietic malignancy but also solid tumors. Because CXCR4 is an attractive target for tumor therapy, reliable preclinical murine models using anti-CXCR4 monoclonal antibodies (mAbs) have been warranted. This study established a novel anti-mouse CXCR4 (mCXCR4) mAb using the Cell-Based Immunization and Screening method. Flow cytometric analysis showed that an anti-mCXCR4 mAb, Cx₄Mab-1 (rat IgG_2a, kappa), recognized mCXCR4-overexpressed Chinese hamster ovary-K1 (CHO/mCXCR4) cells and endogenously mCXCR4-expressing mouse myeloma P3X63Ag8U.1 (P3U1) cells. Furthermore, Cx₄Mab-1 did not recognize mCXCR4-knockout P3U1 cells. The dissociation constants of Cx₄Mab-1 for CHO/mCXCR4 and P3U1 were determined as 6.4 × 10^-9 M and 2.3 × 10^-9 M, respectively, indicating that Cx₄Mab-1 possesses a high affinity to both endogenous and exogenous mCXCR4-expressing cells. These results indicate that Cx₄Mab-1 could be a useful tool for preclinical mouse models.