We have investigated possible intercellular transfer of Sph between heterogeneous and homogeneous cells, utilizing different abilities on conversion of Sph into GlcCer. Murine IL-2-dependent T lymphocyte CTLL cells metabolize exogenously added Sph to GlcCer through Cer within 30 min, whereas fibroblast BALB/C A31 cells required more than 2 h. Thus, CTLL cells exhibiting the active conversion were used as recipient cells, whereas A31 cells where the conversion was slow and fumonisin B1 (inhibition of Cer biosynthesis)-treated CTLL cells being donor cells. To test intercellular transfer of Sph, donor cells incorporated radioactive Sph were coincubated with CTLL cells and GlcCer was examined. The present experiments described the possible transfer of Sph between heterogeneous (from A31 cells to CTLL cells) and homogeneous cells (from fumonisin B1-treated CTLL cells to CTLL cells).