Bm1–Bm5 Classification of Peripheral Blood B Cells Reveals Circulating Germinal Center Founder Cells in Healthy Individuals and Disturbance in the B Cell Subpopulations in Patients with Primary Sjögren’s Syndrome

Abstract

Analyses of B cells in the bone marrow and secondary lymphoid tissues have revealed a broad range of cell surface markers defining B cell subpopulations, but only a few of these have been used to analyze B cell subpopulations in peripheral blood (PB). We report here the delineation of circulating PB B cell subpopulations by staining for CD19, CD38, and IgD in combination with CD10, CD44, CD77, CD95, CD23, IgM, and the B cell memory marker CD27. The utility of this approach is shown by the demonstration of disturbances of circulating B cell subpopulations in patients with autoimmune disease. Five mature B cell (Bm) subpopulations were identified in normal PB that were comparable with the tonsillar Bm1, Bm2, early Bm5, Bm5 subpopulations and, surprisingly, to the germinal center (GC) founder cell subpopulation (Bm2′ and Bm3δ–4δ), suggesting that some GC founder cells are circulating. No PB B cells resembled the Bm3 and Bm4 GC cells. Remarkably, some cells with the CD38−IgD+ phenotype, previously known as naive Bm1 cells, expressed CD27. The CD38−IgD+ subpopulation therefore includes both naive Bm1 cells and IgD+ memory B cells. This new classification of B cell developmental stages reveals disturbances in the proportions of B cell subpopulations in primary Sjögren’s syndrome (pSS) patients compared with healthy donors and rheumatoid arthritis patients. Patients with pSS contained a significantly higher percentage of B cells in two activated stages, which might reflect a disturbance in B cell trafficking and/or alteration in B cell differentiation. These findings could be of diagnostic significance for pSS.

Dysregulation of chemokine receptor expression and function by B cells of patients with primary Sjögren's syndrome

“…Recent studies have shown disturbances in peripheral B cell populations in primary SS, with significantly enhanced CD27Ϫ naive and diminished CD27ϩ memory B cells (6,8,9). This was confirmed in the present study.…”

“…The frequency of peripheral CD27ϩ,CD19ϩ memory B cells was significantly reduced in patients with primary SS compared with healthy control subjects (mean Ϯ SD 13.3 Ϯ 12.3% versus 25.6 Ϯ 7.2%; P Յ 0.0014), whereas the frequency of CD19ϩ,CD27Ϫ naive B cells was significantly enhanced in patients with primary SS (mean Ϯ SD 86.1 Ϯ 12.0% versus 74.4 Ϯ 7.2%; P Յ 0.0014) as reported previously (6,8,9). To ensure that these alterations in patients with primary SS did not further influence the analyses, either CD19ϩ,CD27Ϫ or CD19ϩ,CD27ϩ B cells were gated, and the chemokine receptor expression was subsequently analyzed within each subpopulation ( Figures 1A and B).…”

“…Besides antigen-driven clonal proliferation of B cells (3,5), analyses of inflamed glandular tissue from patients with primary SS also reveal a polyclonal accumulation of CD27ϩ memory B cells and CD27 high plasma cells (6,7). Moreover, immunophenotyping studies indicate that there is disturbed B cell homeostasis in patients with primary SS, with diminished frequencies and absolute numbers of peripheral CD27ϩ memory B cells (6,8,9). More recently, a single-cell messenger RNA (mRNA) study showed further abnormalities, especially in the mechanisms of heavy chain switch recombination (10).…”

Expansion of Functionally Immature Transitional B Cells Is Associated with Human-Immunodeficient States Characterized by Impaired Humoral Immunity

“…Several studies have suggested that these B cells can also be detected in the PB of normal individuals, as well as patients with SLE (19,53). Interestingly, the frequency of such cells in normal individuals is similar to that of transitional B cells; ϳ2-3% (53).…”

“…A population of B cells in human tonsil has been described as pre-GC or GC founder cells (19,52,53). Several studies have suggested that these B cells can also be detected in the PB of normal individuals, as well as patients with SLE (19,53).…”