Fig. 2.

BambL activates peripheral human B cells but becomes cytotoxic at increasing concentrations. B cells were enriched from peripheral blood mononuclear cells (PBMCs) and cultivated in the presence of three different BambL concentrations or left unstimulated for 4 days (n = 1 for each data point). Samples were analyzed by flow cytometry after each day. a BambL is cytotoxic to B cells. Histograms of DAPI fluorescence (first row) and light scattering plots (second row) of ungated cells after 16 h of lectin exposure demonstrate that 0.1 µg/mL BambL is tolerated well, but higher concentrations become increasingly cytotoxic. b BambL stimulates surface CD69 expression. Viable B cells (DAPI⁻ CD19⁺) were identified in the lymphocytes gate in a and analyzed for surface CD69 fluorescence. Histograms depict the time course over 4 days. c All B cell subsets are affected by BambL. Viable naive (‘N’, IgD⁺ CD27⁻), marginal‑zone (‘MZ’, IgD⁺ CD27⁺) and class-switched memory (‘SM’, IgD⁻ CD27⁺) B cells were identified in samples after 16 h lectin exposure (scatter plots in first row, numbers in quadrants represent subset proportions). Surface CD69 fluorescence intensities are presented as histograms in the second row. While all subsets experienced an increase in surface CD69, the naive cells displayed the strongest response