SIRP alpha (CD172a) Biosimilar Antibodies

Target Information

SIRP alpha (CD172a, signal-regulatory protein alpha) is a receptor-type transmembrane glycoprotein expressed on cells of myeloid origin, including granulocytes, dendritic cells (DCs), macrophages, mast cells and hematopoietic stem cells. SIRP alpha acts as a substrate for several activated tyrosine kinases, including EGFR, PDGFR, src and insulin receptor and is involved in the negative regulation of receptor tyrosine kinase-coupled signaling pathways. The ligand binding of SIRP alpha to integrin-associated protein CD47 results in tyrosine kinase phosphorylation of immunoreceptor tyrosine-based inhibitory motifs (ITIMs) within the cytoplasmic region of SIRP alpha, which mediates the recruitment and activation of the tyrosine phosphatases SHP-1 and SHP-2. Ligation of SIRP alpha with CD47 has been demonstrated in several regulatory processes, including the inhibition of host cell phagocytosis by macrophages and the bi-directional activation of T cells and DCs. SIRP alpha has regulatory effects on cellular responses induced by serum, growth factors, insulin, oncogenes, growth hormones and cell adhesion, and plays a general role in different physiological and pathological processes. Cancer cells highly express CD47, which activates SIRP alpha and inhibits macrophage-mediated destruction of cancerous cell growth.