CD300f (also known as CLM-1 or LMIR5) is a transmembrane protein belonging to the CD300 family of immune regulators, primarily expressed on myeloid cells (e.g., neutrophils, macrophages, dendritic cells) and some lymphocytes. It features a unique dual-signaling structure, containing both immunoreceptor tyrosine-based activation (ITAM) and inhibition (ITIM) motifs in its cytoplasmic domain, enabling context-dependent immune modulation. CD300F antibodies are tools designed to target this receptor, either blocking or engaging its function. Research highlights its role in balancing pro- and anti-inflammatory responses, influencing phagocytosis, cytokine production, and cell survival. In disease models, CD300F antibodies have been explored for modulating sepsis, autoimmune disorders, and cancer by altering immune cell activity. For example, CD300F activation may suppress excessive inflammation in sepsis but enhance antitumor responses in certain malignancies. Its ligands include phospholipids like phosphatidylserine, linking it to apoptotic cell clearance. Current studies focus on clarifying its signaling pathways and therapeutic potential, particularly in conditions where immune dysregulation drives pathology. CD300F antibodies thus serve as both investigative reagents and candidates for immunotherapy development.