CXCR5 and AIDS: Using multicolor flow cytometry to detect TFH and TFR cells in cryopreserved peripheral blood mononuclear cells from HIV-infected and non-infected participants in the UCLA Multicenter AIDS Cohort Study (MACS), we identified CD3+CXCR5+CD4+CD8−BCL6+ peripheral blood TFH (pTFH) cells and CD3+CXCR5+CD4+CD8−FOXP3+ peripheral blood TFR (pTFR) cells.