SLAMF1 (Signaling Lymphocyte Activation Molecule Family Member 1), also known as CD150. is a cell surface receptor belonging to the SLAM family of immunoregulatory receptors. Expressed on immune cells, including T cells, B cells, dendritic cells, and macrophages, SLAMF1 functions as a self-ligand that modulates both activating and inhibitory signaling pathways. Structurally, it contains an extracellular immunoglobulin variable (IgV)-like domain, a transmembrane region, and a cytoplasmic tail with immunoreceptor tyrosine-based switch motifs (ITSMs). These ITSMs recruit adaptor proteins like SAP (SLAM-associated protein) to mediate downstream signaling, influencing immune cell activation, differentiation, and cytokine production.
SLAMF1 plays dual roles in immunity. It enhances T-cell and B-cell interactions during adaptive immune responses but also serves as a receptor for measles virus, facilitating viral entry. In cancer, SLAMF1 is implicated in tumor microenvironment regulation, with studies linking its expression to lymphoma progression and immune evasion. Therapeutic antibodies targeting SLAMF1 are being explored to modulate immune responses in malignancies and autoimmune diseases. For instance, blocking SLAMF1 may suppress pathogenic T-cell activity in autoimmunity, while agonistic antibodies could enhance anti-tumor immunity.
Research also highlights SLAMF1's role in immune checkpoint regulation, potentially synergizing with PD-1/CTLA-4 inhibitors. Its aberrant expression in diseases like lupus and chronic lymphocytic leukemia underscores its clinical relevance. However, the functional complexity of SLAMF1 signaling—dependent on SAP and contextual immune cues—requires careful therapeutic targeting to balance efficacy and safety.