Direct transfer of beta-glucuronidase from mouse macrophages to other types of cell.
Rabbit polyclonal antibodies were raised against beta-glucuronidase purified from mouse liver. This antiserum immunoprecipitated the beta-glucuronidase secreted by mouse fibroblasts but did not cross-react with the same enzyme isolated from human tissue. The beta-glucuronidase present in mouse 3T3 fibroblasts and mouse peritoneal macrophages was clearly identified by indirect immunofluorescence, using the antiserum and an FITC-conjugated second antibody, while human fibroblasts with normal levels of beta-glucuronidase activity did not fluoresce when tested with the same reagents. A range of human fibroblasts, human neuroblastoma and rat glioma cells did not fluoresce when incubated with the antibody but did fluoresce after they had been co-cultured for 24 h with mouse macrophages, showing that mouse beta-glucuronidase had been transferred from adherent macrophages into adjacent recipient cells. Transfer took place even when receptor-mediated endocytosis was blocked with a suitable competitive ligand, the transferred enzyme being visible mainly as a bright punctate fluorescence with a lysosome-like distribution. Macrophages thus have the potential to act as donors of lysosomal enzymes to a wide range of recipient cells and to transfer enzymes to them during direct cell-to-cell contact.
D000818:Animals; D002450:Cell Communication; D005347:Fibroblasts / Q000201:enzymology; D005455:Fluorescent Antibody Technique; D005910:Glioma / Q000201:enzymology; D005966:Glucuronidase / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000201:enzymology; D008264:Macrophages / Q000201:enzymology*; D051379:Mice; D009447:Neuroblastoma / Q000201:enzymology; D011817:Rabbits; D051381:Rats
D005966:Glucuronidase