Figure 2

Cytotoxic granules in wild-type cytotoxic T lymphocytes (CTLs) and in CTLs from patients with genetic defects. A, Illustrations of the distribution of cytotoxic granules on microtubules (lines) in a resting human CTL (left panel). Perforin and granzyme are represented as red and green circles inside granules; one granule of each only is shown for clarity. After a CTL encounters a target cell, cytotoxic granules polarize and move along microtubules (middle panel) to the microtubule organizing centre (in blue), which migrates to the immunologic synapse and induces apoptosis of the target cell after the endocytosis of cytotoxic granules in its cytoplasm (right panel). B, Illustration of images of CTLs from patients lacking Lyst (Chédiak-Higashi syndrome), MUNC13-4 (FHL3), or RAB27A (Griscelli syndrome 2) conjugated with target cells.