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Updated: Jun 13, 2026
A Colorimetric Assay that Specifically Measures Granzyme B Proteolytic Activity: Hydrolysis of Boc-Ala-Ala-Asp-S-Bzl
Published on: November 28, 2014
Granzyme B is recovered by natural killer cells via clathrin-dependent endocytosis
Pan Li1, Guoying Zheng, Yan Yang
1Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
When they recognize a target cell, natural killer (NK) cells mount an attack to kill the target by exerting their cytotoxicity via the exocytosis of cytotoxic granules. Although the details of this process (which includes the movement of cytotoxic granules in the immune synapse and their fusion with the plasma membrane, releasing granzymes and perforin into the synaptic cleft) are relatively better understood, the post-exocytosis regulation of the process is still largely unknown. Here we show that a clathrin-dependent endocytosis stimulated by target cell occurs in NK92 cell line, which is closely correlated with granzyme B recovery. Inhibition of the endocytosis significantly attenuates the cytotoxicity of NK92 cells. The NK cell recovery of its released effector molecules, in turn, suggests that endocytosis may well play a key role in the post exocytosis regulation of immune cells.
When they recognize a target cell, natural killer (NK) cells mount an attack to kill the target by exerting their cytotoxicity via the exocytosis of cytotoxic granules. Although the details of this process (which includes the movement of cytotoxic granules in the immune synapse and their fusion with the plasma membrane, releasing granzymes and perforin into the synaptic cleft) are relatively better understood, the post-exocytosis regulation of the process is still largely unknown. Here we show that a clathrin-dependent endocytosis stimulated by target cell occurs in NK92 cell line, which is closely correlated with granzyme B recovery. Inhibition of the endocytosis significantly attenuates the cytotoxicity of NK92 cells. The NK cell recovery of its released effector molecules, in turn, suggests that endocytosis may well play a key role in the post exocytosis regulation of immune cells.
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