CD103⁺ Treg cells induced apoptosis of autoantibody-secreting plasma cells. (A) Twenty days after infusion of CD103⁺ Treg cells, the spleen cells of the untreated and treated recipients were stained for B220 versus syndecan. The percentage of syndecan⁺ plasma cells and syndecan⁻B220⁺ B cells is shown beside the gating box. One representative of 4 examined recipients is shown. The means (± SE) of syndecan⁺ cells versus syndecan⁻B220⁺ cells in the untreated and treated recipients are 4.1% (± 0.4%) versus 1.0% (± 0.2%) and 34.5% (± 4.5%) versus 33.9% (± 3.8%), respectively. (B) Spleen cells (10⁶) of the untreated recipients, including whole spleen (SPL), syndecan⁺ cell–depleted spleen (Syn⁻-SPL), sorted syndecan⁺ cells (Syn⁺), sorted syndecan⁻B220⁺ cells (Syn⁻), were cocultured with or without sorted CD103⁺ or CD103⁻CD4⁺ T cells (0.2 × 10⁶) from the spleen of chronic GVHD recipients for 5 days. Anti-dsDNA IgG in the culture supernatant was measure by enzyme-linked immunosorbent assay. The mean (±SE) of 4 replicated experiments is shown. N/A indicates an antibody concentration below detectable levels. (C) Sorted activated syndecan⁺ and syndecan⁻B220⁺ B cells from chronic GVHD recipients and B220⁺ B cells from normal donors were cocultured with CD103⁺ or CD103⁻CD4⁺ T cells from chronic GVHD recipients for 8 hours. Thereafter, the cells were stained for annexin V versus DAPI. The percentage of annexin V⁺DAPI⁺ cells among Syn⁺ or sydecan⁻B220⁺ cells is shown beside the gating box. One representative of 4 replicated experiments is shown. The means (± SE) of the percentage of annexin V⁺DAPI⁺ cells among recipient syndecan⁺ cells are 5.4% (± 1.3%), 28.6% (± 3.6%), and 6.1% (± 1.7%), respectively, when cocultured alone or cocultured with CD103⁺ or CD103⁻CD4⁺ T cells. Similarly, the means (± SE) percentage among recipient syndecan⁻B220⁺ cells are 6.5% (± 1.9%), 15.4% (± 2.5%), and 6.8% (± 1.3%), and the mean (± SE) percentage among donor B220⁺ B cells are 5.5% (± 1.3%), 6.3% (± 1.5%), and 7.7% (± 1.4%).