Significantly higher percentage of circulating CD27(high) plasma cells in systemic lupus erythematosus patients with infection than with disease flare-up

Abstract

Purpose: To distinguish lupus flare-up from infection in systemic lupus erythematosus (SLE), we analyze the expression of circulating CD27(high) plasma cells in SLE patients with and without infection, in comparison to non-SLE patients with infection.

Materials and methods: The percentage of circulating CD27(high) plasma cells was measured by flow cytometry in the following four groups: 36 SLE patients without infection, 23 SLE patients with infection, eight non-SLE patients with infection, and 26 healthy controls.

Results: The frequency of CD27(high) plasma cells had a correlation with the SLE disease activity index (SLEDAI) (r = 0.866, p < 0.05), level of anti-dsDNA (r = 0.886, p < 0.05), C3 (r = - 0.392, p < 0.05), and C4 (r = - 0.337, p < 0.05) in SLE patients without infection, but there was no correlation with disease activity in SLE patients with infection. Among three groups in particular-SLE without infection, SLE with infection, and non-SLE with infection- the percentages of CD27(high) plasma cells were elevated. The percentage of CD27(high) plasma cells was higher in SLE patients with infection, when compared to SLE patients without infection.

Conclusion: The percentage of CD27(high) plasma cells is a biomarker for disease activity of SLE without infection, under correlation with SLEDAI, anti-dsDNA, and C3 and C4 level. However, when the SLE patients have an infection, the percentage of CD27(high) plasma cells is not an adequate biomarker for the survey of disease activity. The percentage of CD27(high) plasma cells may serve as a potential parameter to distinguish a lupus flare-up from infection.

Fig. 1

Comparison of the percentage of overall CD27^high plasma cells from four groups (SLE, SLE with infection, Non-SLE with infection, healthy control). SLE, systemic lupus erythematosus; HC, healthy control.

Fig. 2

Different expressions of peripheral CD27^high plasma cells in the four patient groups. (A) SLE with pulmonary haemorrhage (18%). (B) SLE with Streptococcus pneumonia infection (63%). (C) Non-SLE with Staphylococcus aureus infection (54%). (D) Healthy control (2%). SLE, systemic lupus erythematosus

Fig. 3

In an SLE patient with Streptococcus pneumonia infection, after the antibiotics therapy, there was a significant decline in the percentage of CD27^high plasma cells one month later (33% to 11%). The high level of CRP decreased to normal range (4.2 mg/dL to 0.31 mg/dL). SLE, systemic lupus erythematosus; CRP, C-reactive protein.