Cultured SCS were stained, data acquired and analyzed as previously described using the following antibodies [11] (link); Surface: CD3-Qdot-605, CD4-Qdot-655 (Invitrogen), CXCR5-Alexa-488, CD25-APC-Cy7, PD-1-Brilliant Violet-421; Intracellular: Bcl-6-PE-CF594, active caspase-3-PE (BD Biosciences), and FoxP3-PE-Cy7 (eBioscience).
FL T-cell subsets were flow cytometrically sorted using the following markers; T-cell: DAPI−CD3+CD4+CD19−; TFH: Propidium iodide−CD3+CD4+CXCR5+PD-1+CD25−. Following the sort, an aliquot of TFH were permeabilized and stained with Bcl-6 and FoxP3 to confirm the TFH phenotype. TFH cells were defined as CD3+CD4+CXCR5+PD-1+CD25−Bcl-6+; TFR were defined as CD3+CD4+CXCR5+PD-1+CD25+Bcl-6+FoxP3+ and Tregs were defined as CD3+CD4+CD25+FoxP3+.