Objectives: Monitoring of peripheral B cell subsets in patients with SLE revealed an activity-related expansion of CD27++CD20-CD19dim Ig-secreting cells. A similar subset has also been identified 6-8 days after tetanus/diphtheria vaccination in normal individuals and in patients with infectious disease.
Methods: We analyzed this subset further focussing on the HLA-DR surface expression in a cohort of 25 patients with SLE.
Results: This study revealed that 86% (range: 59-97%) of CD27++CD20-CD19dim cells express high levels of HLA-DR, are also expanded in the bone marrow (BM), and represent plasmablasts enriched with anti-dsDNA secreting cells. The remaining CD27++CD20-CD19dim cells were HLA-DRlow and represent mature plasma cells. Importantly, HLA-DRhigh plasmablasts showed a closer correlation with lupus activity and anti-dsDNA levels than the previously identified CD27++CD20-CD19dim cells.
Conclusion: HLA-DRhighCD27++CD20-CD19dim plasmablasts represent a more precise indicator of lupus activity and suggest that there is an overproduction or lack of negative selection of these cells in SLE.