| Abstrakt: |
Various natural and synthetic substances classified as polyanlonics have been Implicated in antagonizing phagosome‐lysosome fusion in cultured macrophages. The phenomsnon has been Judged by comparing the transfer of selected markera from secondary lysosomes to phagosomes in control and in “polyanion” cells. Our earlier studies showed that use of one of the markers, the membrane per mealing acridine orange, was plagued with artifacts that were especially misleading in the presence of polyanionic agents. We now question the validity of data obtained by the alternative technique, electron microscopy. Our present evidence shows that nonionic hydrocolloids of sufficiently high molecular weight prevent the transfer of various colloidal electron‐opaque markers from lysosomes to phagosomes in the same manner as does the powerful polyanionic “fusion inhibitor” dextran sulfate. Both kinds of hydrocolloids, however, allow delivery of lysosomal, low‐molecular‐weight highly charged non‐permeant fluorescent markera to phagosomes, probably by a fusion process. We propose that neither type of hydrocolloid inhibits fusion; instead, when sufficiently concentrated, they trap particulate electron‐opaque markers in a gelatinous matrix, which may move only slowly out of lysosomes. The potyanionics trap the electron‐opaque markers physically and acridine orange ionically. Hence, the semblance of “fusion inhibition.” |
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