CD52 and systemic lupus erythematosus: Like cell-bound CD52, soluble CD52 was significantly elevated in SLE plasma compared to HC plasma (median [IQR] of HC vs. SLE: 8.69 [5.27, 13.01] vs. 18.36 [7.98, 21.93] ng/ml; p = 0.0074)(Figure 2A).