Lipophosphoglycan (LPG) reduced the migration of Langerhans cells (LC). (a) Efflux of LC from skin explants cultured in the absence of exogenous mediators or in the presence of lipopolysaccharide (LPS), tumour necrosis factor-α (TNF-α) or LPG. Major histocompatibility complex (MHC) class II-positive cells that had migrated from the skin into the medium were detected by fluorescence-activated cell sorter (FACS) analysis (cells in the absence of exogenous mediators versus LPS, P < 0·0001; versus TNF-α, P < 0·002; versus LPG, P < 0·0008). (b) Transwell migration of isolated LC cultured in the absence of exogenous mediators or in the presence of LPS, TNF-α, Leishmania major-conditioned medium (LCM), LPG or phosphoglycan (PG). Cells that had migrated to the bottom chambers were enumerated, and LC were identified by FACS analysis for expression of MHC class II (LC in the absence of exogenous mediators versus LPS, P < 0·0001; versus TNF-α, P < 0·0002; versus LPG, P < 0·001).