Feng M, et al. - Researchers evaluated 36 hospitalized systemic lupus erythematosus (SLE) patients with bacterial infection and 45 with lupus flare without infection to study the diagnostic performance of complement C3, complement C4, C-reactive protein (CRP), procalcitonin (PCT), white blood cell count (WBC), neutrophil CD64 (nCD64) index, lymphocyte subsets and their combination in distinguishing bacterial infection from disease relapse in SLE. They observed CRP, WBC and nCD64 index were higher in the infected group, while C3, C4 and B cells levels were lower. They recorded 0.00, 39.29, 59.10, 61.54 and 100.00% as the bacterial infection rate in patients with bioscore ≤2, 3, 4, 5 and 6, respectively. They suggested there was utility of the combination of nCD64 index, C3, C4, CRP, WBC and B cells in a bioscore to diagnose bacterial infection in SLE.