Polyanionic agents do not inhibit phagosome-lysosome fusion in cultured macrophages.

The survival of some intracellular pathogens within macrophages may be aided by an ability of the organism to antagonize, from within the entrapping phagosome, its fusion with lysosomes. On the other hand, certain polyanionic agents have been implicated in imposing a similar block to fusion from the lysosomal domain--because the transfer of various foreign markers from lysosomes to newly formed phagosomes is remarkably inhibited in these polyanion-containing cells. Based on an analysis of various observations and our own recent data, we propose that the polyanionics do not, in fact, prevent phagosome-lysosome fusion but, instead, physically entrap the usual markers in a gelatinous matrix within the lysosomes. This view accounts for many paradoxical consequences of polyanionic accumulation and for the curiously normal behavior of macrophages that are presumed to be suffering from such a crucial intracellular dysfunction.