CD1b tetramers identify a mycobacterial glycolipid-reactive T cell repertoire in humans. (a) PBMCs of four subjects infected with Mycobacterium tuberculosis were stained with CD1b tetramers in addition to CD3 FITC, CD14 PercP-Cy5.5, CD19 PerCP-Cy5.5, and violet viability dye and gated on live lymphocytes. (b) PBMCs from patient 1 were cultured overnight in 0.2 ng/ml IL-15 before FACS sorting. PBMCs from patient 2 were expanded by stimulation with anti-CD3 in the presence of irradiated feeder cells and IL-2 before FACS sorting using CD3 FITC and CD1b tetramers. Equal numbers of cells were incubated with 20,000 CD1b or empty vector–transfected K562 APCs with or without 5 µg/ml GMM (mean + SEM).