hIRA B cells have phagocytic capacity.

<p>A) Tonsil-derived cells were incubated for 2 h at 37°C with heat-inactivated <i>S</i>. <i>aureus</i> at 1:10 (cells:bacteria) MOI. After staining with anti-CD19 (Blue), anti-GM-CSF (Orange), and anti-MPO (Red), different optical fields were analyzed by confocal microscopy. The enlargement (bright field merged with the GM-CSF channel, right panel) shows the presence of <i>S</i>. <i>aureus</i> internalized by a CD19⁺GM-CSF⁺MPO⁺ cell (white arrows) and two CD19⁺GM-CSF^-MPO^- cells with non-internalized bacteria (yellow arrows). B) <i>Left panels</i>: similar experimental approach described for panel A) with the addition of PhRodo labelled <i>S</i>. <i>aureus</i> bioparticles (green). The white arrows indicate not-internalized bioparticles (low fluorescence intensity), while bright fluorescent bioparticles localize within a CD19⁺GM-CSF⁺MPO⁺ cell (white square) but not within a conventional CD19⁺ cell (yellow square); <i>right panels</i>: control experiment where cells were incubated with PhRodo labelled <i>S</i>.<i>aureus</i> bioparticles (dark green) for 2 h at 4°C. Data are representative of 3 independent experiments. Scale bar = 10 μm.