ABSTRACT
Infection is one of the major complications as well as cause of death in systemic lupus erythematosus patients [SLE]. Differentiation between early infection and disease flare in these patients is often clinically difficult because both have similar signs and symptoms. To evaluate CD64 expression on neutrophils as an early marker that can discriminate between infection and disease flare in SLE patients. Also, its clinical utility in comparison with traditional laboratory tests used for detecting infection will be studied. The study included 38 subjects; 10 apparently healthy individuals as healthy controls and 28 SLE patients divided into three groups [10 SLE patients with infection, 10 SLE patients with flare and 8 SLE patients without infection or flare]. CD64 on neutrophils was measured using flow cytometry. Total leucocytic count, erythrocyte sedimentation rate and high-sensitive C-reactive protein were also measured. The median of the percentage of neutrophils expressing CD64 was higher in all SLE patients compared to normal control. It was significantly higher in SLE patients with infection than those with disease activity [P 0.001]. Using a cutoff value of >/= 17.6,% of neutrophils expressing CD64; it revealed 100% sensitivity and 100% specificity. The results of the present work showed that measurement of CD64 expression on neutrophils could be used as a sensitive and specific marker for detection of infection in SLE patients and differentiation between infection and disease activity