Figure 2.

Dsg3-specific memory B cells are increased in remitting PV patients on minimal therapy. (A) Representative FACS plot showing staining for CD19⁺Dsg3-AF647⁺ B cells in one PV patient. (B) On the upper row: Dsg3-specific B cell populations (total CD19⁺, CD19⁺CD27⁻ mature naïve, CD19⁺CD27⁺ memory, and CD19⁺CD27^hiCD38^hi plasmablasts) were analyzed in PV patients (n = 14) and healthy controls (HC; n = 14). On the lower row: PV patients were further subdivided based on their systemic treatment into minimal to no (n = 6) and moderate therapy (n = 8) showing highest numbers of Dsg3-specific CD19⁺CD27⁺ memory B cells on minimal therapy. ■: after Rituximab treatment; □: no Rituximab treatment. (C) CD19⁺CD27⁺Dsg3-AF647⁺ cells were isolated from peripheral blood of a PV patient and a healthy control by FACS sorting and stimulated with R848 and IL-2 to induce plasma cell differentiation. Dsg3-IgG-secreting and total IgG-secreting B cells were subsequently detected using ELISpot by seeding 250 cells per well on ELISpot plates coated either with recombinant human Dsg3 or human collagen VII as control protein. Statistical analysis was performed with two-tailed nonparametric Mann-Whitney-U-Test. Differences between groups were considered statistically significant at p-values of <0.05 indicated as ^*.