Specific binding of clonal immunoglobulins to Gaucher lysolipids. (A-B) Serum protein electrophoresis (SPEP) for patient 1 and patient 2 highlighting a monoclonal protein peak in the beta 2 and the gamma regions, respectively. (C) A schematic representation of the protein pull-down process using lipid-coated C18 beads from patient serum. (D) Western blot analysis demonstrating the binding of monoclonal IgA to lipid-coated C18 beads for patient 1. (E) Western blot analysis demonstrating binding of monoclonal IgG (gamma) for patient 2. The lipids cholesterol, phosphatidylcholine (PC), and Gly-sphingosine were used at the following ratios (w:w): cholesterol/PC (2:4) for control liposomes and cholesterol/PC/Gly-sphingosine (2:6:2 or 2:4:4) for Gly-sphingosine-containing liposomes. (F) A schematic depicting the sphingosine-coated beads pull-down assay from patient serum. (G-H) Western blot analyses demonstrating specific binding of immunoglobulin IgA to sphingosine-coated beads (S-1-P) for patient 1 and IgG (gamma) for patient 2, respectively. Blocked agarose beads were used as a negative control (C) with lipid-coated beads. Illustrations for schematic representations (C) and (F) were created with BioRender.com.