Abstract
CD47 is a self-marker expressed on the surface of RBCs and work to prevent the process of phagocytosis. SIRP alpha is the ligand of CD47 that is expressed on the surface of phagocytic cells, such as macrophages, to control the removal of dead/diseased cells. This study aimed to examine the expression of CD47 on RBCs and SIRP alpha on PBMC cells in SCD patients and the apoptosis of SCD RBCs. We also measured the levels of pro-inflammatory cytokines in SCD patients and correlated it with the cell surface marker expression of CD47 and SIRP alpha to determine whether CD47 and/or SIRP alpha played a role in promoting the pro-inflammatory phenotype in SCD. Whole blood samples were drawn from SCD patients, and healthy control and PBMC were isolated and stained with SIRP alpha. Change in CD47, apoptosis by annexin V marker, and pro-inflammatory cytokines were measured and correlation among these variants was determined. The expression of CD47 was significantly decreased and the apoptosis was increased in RBCs of SCD patients. A higher level of pro-inflammatory cytokines, IL-6 and IL-1 beta, was found in SCD patients and IL-1 beta was found to be inversely correlated with SIRP alpha expression. Our data showed that CD47 of erythrocytes of SCD samples is reduced and that the apoptosis is increased in those patients. Based on the role of CD47, we suggest that increased apoptosis in SCD would be impacted by the reduced level of CD47. An inverse relationship was found between SIRP alpha marker on PBMC and the increased production of pro-inflammatory cytokines in SCD.