SIRPA and infection: The role of CD47 as a regulatory molecule was initially identified in red blood cells; however, several studies have shown CD47 to play crucial roles in homeostasis, immune regulation, stress, tumor, infection, atherogenesis, etc. CD47 has high binding affinity to SIRPa, TSP-1 and other integrin molecules on platelets, sickle red blood cells, microglia, B lymphocytes, etc. [51,52,53,54,55].