CD93, also known as Complement component C1q receptor, is receptor (or element of a larger receptor complex) for C1q, mannose-binding lectin (MBL2) and pulmonary surfactant protein A (SPA). This protein mediates the enhancement of phagocytosis in monocytes and macrophages upon interaction with soluble defense collagens. It may play a role in intercellular adhesion. This protein was expressed on (pre)plasmablasts/plasma cells, including long-lived plasma cells that showed decreased cell cycle activity, high levels of isotype-switched Ig secretion, and modification of the transcriptional network. It is important for the maintenance of plasma cells in bone marrow niches. Recombinant mouse CD93, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.