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. 2015:2015:939783.
doi: 10.1155/2015/939783. Epub 2015 Jul 26.

Analysis of Erythrocyte C4d to Complement Receptor 1 Ratio: Use in Distinguishing between Infection and Flare-Up in Febrile Patients with Systemic Lupus Erythematosus

Chen-Hung Chen  1 , Shun-Ban Tai  2 , Hsiang-Cheng Chen  3 , Deng-Ho Yang  4 , Ming-Yieh Peng  5 , Yuh-Feng Lin  6
Affiliations

Analysis of Erythrocyte C4d to Complement Receptor 1 Ratio: Use in Distinguishing between Infection and Flare-Up in Febrile Patients with Systemic Lupus Erythematosus

Chen-Hung Chen et al. Biomed Res Int. 2015.

Abstract

Objective: Fever in systemic lupus erythematosus (SLE) can be caused by infection or flare-up of the disease. This study aimed to determine whether the ratio of the level of erythrocyte-bound C4d to that of complement receptor 1 (C4d/CR1) can serve as a useful biomarker in the differentiation between infection and flare-up in febrile SLE patients.

Methods: We enrolled febrile SLE patients and determined the ratio on the day of admission. The patients were divided into 2 groups according to the subsequent clinical course.

Results: Among the febrile SLE patients, those with flare-up had higher ratios and lower C-reactive protein (CRP) levels than those with infection. Cut-off values of <1.2447 and >4.67 for C4d/CR1 ratio and CRP, respectively, were 40.91% sensitive and 100.0% specific for the presence of infection in febrile SLE patients; similarly, cut-off values of >1.2447 and <2.2, respectively, were 80% sensitive and 100% specific for the absence of infection in febrile SLE patients.

Conclusion: The C4d/CR1 ratio is a simple and quickly determinable biomarker that enables the differentiation between infection and flare-up in febrile SLE patients at initial evaluation. Further, when combined with the CRP level, it is useful to evaluate disease activity in SLE patients with infection.

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Figures

Figure 1
Figure 1
Comparison of the levels of E-C4d and E-CR1 expression and the C4d/CR1 ratio among groups a, b, c, and d. a: febrile SLE patients with infection, b: febrile SLE patients without infection, c: non-SLE febrile patients with infection, and d: healthy controls.
Figure 2
Figure 2
Flow cytometric analysis of E-C4d and E-CR1 expression in (a) febrile SLE patients with infection, (b) febrile SLE patients without infection, (c) non-SLE febrile patients with infection, and (d) healthy controls. Erythrocytes were stained with anti-C4d (black lines, open histogram), CR1-2B11 (dashed lines, open histogram), and isotype-matched control antibodies (solid gray histogram).
Figure 3
Figure 3
Detection of C4d to CR1 ratio and CRP on erythrocytes (E) from febrile SLE patients with infection and febrile SLE patients without infection. Cut-off points determined by receiver operating characteristic (ROC) curve are indicated by solid lines.
See this image and copyright information in PMC

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