In this research endeavor, a multifaceted approach has been employed to investigate the intricate roles of CD300 family proteins in immunological processes. Lentiviral transduction of the L929 cell line with mouse and human CD300f genes, followed by puromycin selection, has established cellular models to examine the functions of these receptors. Concurrently, engineered constructs encoding extracellular domains of mouse CD300lb and CD300ld, fused with human IgG1, have been developed for the production of receptor extracellular domain proteins, facilitating studies on protein interactions. Additionally, genetically modified murine models, including CD300f-deficient mice created on a C57BL/6 background and CD300a-deficient mice obtained as embryos and cross-bred, enable the exploration of the biological functions of these genes in vivo. This comprehensive approach allows for a thorough investigation into the immunological significance of CD300 family proteins across various experimental contexts.