Description: The monoclonal antibody R139 recognizes human CD93, also known as C1qRp. The glycoprotein CD93 binds to C1q, the subunit of the complement protein, mannose binding lectin and pulmonary surfactant protein A. CD93 is predicted to play a role in the clearance of apoptotic cells. Expression of CD93 is confined to myeloid cells with higher expression on monocytes than neutrophils, eosinophils, platelets and endothelial cells. Expression on DC’s is downregulated upon maturation. Additionally, CD93 has been shown to define an early bone marrow stem cell population of hematopoietic and hepatic precursors.
The monoclonal antibody R139 blocks C1q-mediated enhancement of phagocytosis.
CD93 can be shed from the cell surface. This phenomenon can be measured using R3 antibody as detection with R139 as capture to detect soluble CD93 by ELISA. The epitope for R139 resides in the EGF domains.