Figure 6.

Proposed overarching model of cryptococcal cell-to-cell transfer. A. The initial step in transfer, and the point which was defined as the start of exocytosis. The moment when a phagosome (white space) containing an opsonized cryptococcal cell begins to move toward the plasma membrane of the donor macrophage. The phagosome reaches and merges with the plasma membrane of the donor macrophage in a manner which expels the cryptococcal cell. Cytosol is retained within the donor macrophage and excluded from the transfer process. The moment at which the cryptococcal cell is fully expelled from a macrophage was defined as the end of exocytosis. B. The next step of transfer in which the released cryptococcal cell is free to interact with the Fc receptor of the acceptor macrophage via opsonin which survives the initial phagosome. The moment of initial attachment of the cryptococcal cell to the acceptor macrophage defined as the start of phagocytosis. Note the macrophage cells remain in contact but the transfer site is not sealed to the extracellular environment. C. The final step of transfer, the point at which the cryptococcal cell has been fully ingested by the acceptor macrophage. This moment is also used to define the end of phagocytosis. Left. The total time of exocytosis, phagocytosis, and Dragotcytosis denoted by black line and measured time. The total length of Dragotcytosis roughly equals that of exocytosis plus phagocytosis.