کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1105965 | 1488263 | 2006 | 8 صفحه PDF | دانلود رایگان |
CD47 is a widely expressed integral membrane protein, found also on red blood cells where it reportedly has a key role in inhibiting phagocytic clearance of RBC by signaling within a multi-molecular ‘phagocytic synapse’. Calreticulin is postulated to be on the RBC surface and stimulate phagocytosis, whereupon CD47 on the RBC binds SIRPα on the phagocyte and signals a block against phagocytosis. While studies of mouse suggest such an inhibitory role for CD47, CD47 seems to have distinct interactions in human RBC—particularly within a ‘metabolon’ complex of CD47, Rh proteins, and several other proteins. We have assessed the relative density, co-clustering, and mobility of some of the implicated proteins on human RBC versus murine RBC (hu-RBC and mu-RBC, respectively), and we find a few major differences. While RBC from both species express similar densities of CD47 and SIRPα interactions are measurably modest, the interactions prove species-specific. While RBC from both species also have detectable calreticulin, fresh hu-RBC are found to have 10–100-fold more calreticulin binding sites on their surface. Imaging of clusters of SIRPα-CD47 on both species of RBC show that RhD does co-localize with CD47 on hu-RBC, but neither calreticulin nor Glycophorin-A appear enriched in the metabolon complexes. Furthermore, mouse-cells alone tend to aggregate due to cross-bridging by SIRPα complexes, showing accumulation of CD47 in the adhesion zone, which is consistent with a high mobility of CD47 unique to mu-RBC.
Journal: Transfusion Clinique et Biologique - Volume 13, Issues 1–2, March–April 2006, Pages 31–38