B-lymphocyte subsets in IgAN
Based on the expression of the cell surface markers CD19, CD27, CD38 and
IgD, the following B cell subsets were identified in the peripheral
blood of patients with IgAN, ADPKD and HC: naïve B cells (CD19+ CD27-,
IgD+), pre-switched B cells (CD19+ CD27+ IgD+), switched B cells (CD19+
CD27+ IgD-) plasmablasts (CD19+ CD27+ CD38+) and long-lived plasma cells
(CD19-CD27hi CD38hi).
In the peripheral circulation of patients with IgAN, proportions of
pre-switched B cells and plasmablasts were lower than those in HC
(p=0.005 and p=0.01 respectively), while the proportion of CD19-negative
long-lived plasma cells (LLPC) was higher (p=0.02, Fig. 2). There were
no significant differences between patients with IgAN and HC comparing
the proportions of naïve B cells and switched B cells. To assess if
these differences are IgAN- specific, the cell fractions in IgAN
patients were compared to those in ADPKD. A significant difference
between the groups was observed for pre-switched B cells but not for
plasmablasts or LLPC (Fig. 2).
Since we observed a similar proportion of naïve B cells in HC and IgAN
patients, despite the differences in pre-switched B cells, we also
analyzed the ratio between naïve and pre-switched B cells. The ratio
between naïve and pre-switched B cell proportions was higher in IgAN
patients compared to HC (p=0.02) and ADPKD (p=0.02) (Fig. 3).