After 6 days culture, cultured cells were analyzed for expression of surface markers by multi-color flow cytometry. Cell aliquots were treated with anti-human Fc mAb for 20 minutes and stained for 30 minutes with selected combinations of fluorochrome-conjugated antibodies.
For the analysis of B cell subpopulations and activation markers, the monoclonal antibodies used were CD19-PE-CF594 (BD Biosciences, San Jose, CA), CD62L-PE-Cy5 (BD Biosciences), IgD-FITC (BD Biosciences), CD27-PE-Cy7 (BD Biosciences), CD24-PE (BD Biosciences), CD38-PerCP-Cy5.5 (Beckman Coulter, Brea CA), CD138-PE-Cy7 (eBioscience, San Diego, CA), CD23-PE (BD Biosciences), CD21-PE-Cy5 (BD Biosciences), IgG-PC7 (BD Biosciences), CD86-Alexa 700 (BD Biosciences) and CD95-Pacific Blue (BioLegend, San Diego, CA).
For plasma cell staining, cultured cells were first incubated with monoclonal antibodies to surface markers (CD38, CD138 and CD19), fixed and permeabilized with Cytofix/Cytoperm Fixation/Permeabilization Solution Kit (BD Biosciences) and then incubated with Blimp-1-PE (R&D systems) and Pax5-APC (eBioscience) for 30 minutes.
For the proliferation assay, 1–10×106 cells of interest were labeled with 1μM carboxyfluorescein succinimidyl ester (CFSE) (Invitrogen) before culture initiation. After 6 days of culture, cells were harvested, incubated with antibodies, and dilution of CFSE was assessed by flow cytometry.
For the analysis of B cell subpopulations and activation markers, the monoclonal antibodies used were CD19-PE-CF594 (BD Biosciences, San Jose, CA), CD62L-PE-Cy5 (BD Biosciences), IgD-FITC (BD Biosciences), CD27-PE-Cy7 (BD Biosciences), CD24-PE (BD Biosciences), CD38-PerCP-Cy5.5 (Beckman Coulter, Brea CA), CD138-PE-Cy7 (eBioscience, San Diego, CA), CD23-PE (BD Biosciences), CD21-PE-Cy5 (BD Biosciences), IgG-PC7 (BD Biosciences), CD86-Alexa 700 (BD Biosciences) and CD95-Pacific Blue (BioLegend, San Diego, CA).
For plasma cell staining, cultured cells were first incubated with monoclonal antibodies to surface markers (CD38, CD138 and CD19), fixed and permeabilized with Cytofix/Cytoperm Fixation/Permeabilization Solution Kit (BD Biosciences) and then incubated with Blimp-1-PE (R&D systems) and Pax5-APC (eBioscience) for 30 minutes.
For the proliferation assay, 1–10×106 cells of interest were labeled with 1μM carboxyfluorescein succinimidyl ester (CFSE) (Invitrogen) before culture initiation. After 6 days of culture, cells were harvested, incubated with antibodies, and dilution of CFSE was assessed by flow cytometry.