hIRA B cells are present in human tonsils.

<p>A) Gating strategy for the identification of hIRA B cells in tonsils. Tonsil-derived cells were obtained from tonsils of individuals undergoing routine tonsillectomy. After processing in the presence of DNAse and collagenase, samples were stained, fixed and analyzed by flow cytometry. Live cells were discriminated using Aqua Live/Dead staining kit, and singlet lymphocytes were selected on the basis of forward (FSC) and side (SSC) scatters. B cells were further identified as CD19⁺CD20⁺ and analyzed for the expression of GM-CSF. B) Quantification of hIRA B cells in tonsils. The number of CD19⁺CD20⁺GM-CSF⁺ cells was normalized on the number of total CD19⁺CD20⁺ lymphocytes after isotype background subtraction. The bar represents the geometric mean.