CD47 and systemic lupus erythematosus: Subgroup analysis (according to SLE disease activity) revealed that the fold increase in CD47 expression on monocytes was higher when cells were exposed to serum from SLE patients with high disease activity (SLEDAI > 12) (mean fluorescence intensity (MFI): 164.5% ± 21.7%, p = 0.002) or serum from those with low disease activity (SLEDAI < 12) (MFI: 150.3% ± 13.1%, p = 0.001) than when cells were exposed to healthy serum (Figure 2D).