Replication of Cryptococcus neoformans in macrophages is accompanied by phagosomal permeabilization and accumulation of vesicles containing polysaccharide in the cytoplasm

Stephanie C. Tucker, Arturo Casadevall

Research output: Contribution to journalArticlepeer-review

Abstract

Cryptococcus neoformans (CN), an encapsulated, ubiquitous environmental yeast, is pathogenic for humans, primarily those with compromised immune function. CN is believed to be a facultative intracellular pathogen. Time-lapsed video microscopy revealed that yeast began to replicate and divide 2 hours after ingestion by J774.16 macrophage cells, with the average cell hosting 10-40 organisms of varying morphologies before ultimately lysing and releasing organisms, either singly or in clumps. Intracellular growth was accompanied by the accumulation of polysaccharide-filled vesicles in the macrophage. Studies with fluorescently labeled dextran revealed that the phagolysosomal compartment became leaky during the course of intracellular infection. Consistent with this observation, phagosomes containing CN had an increased pH relative to similar phagosomes containing inert magnetic beads, as indicated by a colorimetric change in the pH-sensitive Lysosensor dye. Immunocytochemistry revealed differences in the reactivity of polysaccharide elaborated by CN inside macrophages relative to that expressed in vitro. Taken together these results are suggestive of a novel mechanism of intracellular survival by an encapsulated organism, whereby ingestion is followed by damage to the phagosomal membrane resulting in continuity with the cytoplasm, accumulation of polysaccharide-containing vesicles, and possibly, production of a structurally different polysaccharide.

Original languageEnglish (US)
Pages (from-to)3165-3170
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume99
Issue number5
DOIs
StatePublished - Mar 5 2002
Externally publishedYes

ASJC Scopus subject areas

  • General

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