Fig 1. Tonsillar B-cell subsets have differential expression patterns of BMP receptors.

Single-cell suspensions from human tonsils were stained with lineage markers and anti-BMP receptor antibodies, and analyzed by flow cytometry. (A) Gating strategy to identify B-cell subsets in tonsils: Naïve B cells were defined as CD3^-CD20⁺CD38^-IgD⁺CD27^-, GC B cells as CD3^-CD20⁺CD38⁺IgD^- and plasmablasts as CD3^-CD38^hi. Memory B cells were separated into three subsets: class switched CD20⁺CD3^-CD38^-IgD^-CD27⁺, non-switched CD20⁺CD3^- CD38^-IgD⁺CD27⁺ and class switched CD20⁺CD3^- CD38^-IgD^-CD27^- memory B cells. (B) Histogram overlays of receptor expression in GC and naïve B cells in donor T4. (C) Heatmaps of relative protein expression of BMP type I and type II receptors in tonsils from 4 different donors, denoted T1 –T4. The expression levels were normalized to irrelevant Ab control in each donor, using arcsinh transformation.