CD27+IgD+B cells Demonstrate Dampened IgM-Producing competency in SLE
To determine the functional changes of CD27+IgD+B cells,we then examined the production of IgM by CD27+IgD+B cells in SLE patients. CD27+IgD+B cells from active SLE patients (SLEDAI>5) and healthy individuals were isolated by flow cytometry sorting and subjected to ELISPOT and QPCR analyses. ELISPOT analysis showed that under SLE circumstance, the IgM-producing capacities of these cells were dampened (Figure 3A). QPCR analyses further confirmed that the IgM transcripts of these CD27+IgD+B cells were significantly decreased in SLE (Figure 3B). Taken together, these results indicated that CD27+IgD+B cells were functionally impaired in producing IgM in SLE.
CD27+IgD+B cells are recovered in SLE patients with disease remission after therapy
To ascertain the usefulness of CD27+IgD+ B cells as a biomarker for disease activity, we further evaluated whether these cells would be recovered after effective therapy. 12 patients who were diagnosed as SLE were studied when they were in relapse and 4 weeks after the initiation of treatments. As shown in Table 2, after treatments reduced significantly disease activity as measured by SLEDAI. The anti-dsDNA and 24h urinary protein were decreased with the serum C3 and C4 normalized to some extent. The total number of leukocyte and platelet were increased after the treatments.
The frequency of CD27+IgD+B cells were examined before and after 4 weeks of initiation of treatments are shown in Figure 4A. As measured by SLEDAI, all patients showed a significant reduction in disease activity after treatment (Figure 4B) and the frequency of CD27+IgD+B cells was significantly increased (Figure 4C). All these results suggested that the impaired CD27+IgD+ B cells in SLE patients could be recovered after effective therapy, indicating their deficiency might be correlated with the development of SLE.