Isolation and identification of CD1d-binding lipids from myeloma patient plasma. (A,B) ESI-mass spectra of lipid species from bulk extracts (A) and CD1d-conjugated bead eluents (B) from plasma of 2 myeloma patients (MM1 and MM2). (C) ESI-mass spectra of eluents from beads only control and CD1d beads, spiked with an LPC species (LPC-C14, m/z 368, arrow) as an internal reference. Data shown are representative of findings on 4 separate patients. (D,E) Tandem mass spectra (MS/MS) of major species observed for eluents of myeloma patient studied in panel C. (F) MS/MS of 496.3 of [M + H]⁺. (G) MS/MS of 480.3 of [M-15]. (F) Structure of 1-hexadecanoly-2-hydroxy-sn-glycero-3-phosphocholine, or lysophosphatidylcholine (LPC)-C16:0. (G) Bulk lipids isolated from myeloma patients or healthy donors were used to load CD1d dimers and stain cultures of human T cells as described in “Loading CD1d dimers and detection of CD1d-lipid–reactive T cells.” Numbers represent percentage of cells in the quadrant.