Analysis of neutral glycosphingolipids from Trypanosoma brucei.

Neutral glycosphingolipids (GSLs) were isolated from Trypanosoma brucei and analyzed by thin-layer chromatography (TLC), TLC/secondary ion mass spectrometry (TLC/SIMS), and liposome immune lysis assay (LILA). Three species of neutral GSLs, designated as N-1, -2, and -3 were separated on TLC. N-1 GSL migrated very close to glucosylceramide (GlcCer) and N-2 GSL showed the same mobility as lactosylceramide (LacCer). On the other hand, the mobility of N-3 GSL on the TLC plate was slower than globotetraosylceramide (Gb4). In order to characterize the molecular species of neutral GSLs from T. brucei, N-1, -2 and -3 GSLs were analyzed by TLC/SIMS. The TLC/SIMS analysis of N-1 of the parasites revealed a series of (M-H)- ions from m/z 698 to 825 representing the molecular mass range of ceramide monohexoside (CMH) (GlcCer or galactosylceramide). On the other hand, the TLC/SIMS spectra of N-2 GSL revealed a series of (M-H)- ions from m/z 944-987 indicating the molecular mass range of LacCer. In the TLC/SIMS analysis of N-3 GSL, however, the characteristic molecular ions that can elucidate the structure of N-3 GSL were not obtained. In order to confirm the results obtained from TLC/SIMS, N-1, -2, and -3, GSLs were tested by LILA with specific antibodies against GlcCer, LacCer, and Gb4, respectively. N-1 GSL had reactivity to anti-GlcCer antibody and N-2 GSL reacted with the antibody against LacCer. However, N-3 GSL was not recognized by anti-Gb4 antibody. Using anti-GlcCer and anti-LacCer antibodies, furthermore, we studied the expression of GlcCer and LacCer in T. brucei parasites. Both GlcCer and LacCer were detected on the cell surface of T. brucei.