Leukocyte immunoglobulin like receptor B4 (LILRB4) was considered to promote tumor progression and immunosuppression in various malignancies. As a murine homolog of LILRB4, gp49B has been employed in numerous mouse models to investigate the immunosuppressive properties of LILRB4. However, gp49B differs significantly from LILRB4 in its amino acid sequence and intracellular domains. In this study, we developed a conditional mouse model that overexpresses LILRB4 specifically in myeloid cells to investigate its effects on solid tumors and hematological malignancies. Our results showed that the physiological structure and overall immune system of LILRB4