Identification of a novel class of cytotoxic granules as origin of supramolecular attack particles in T lymphocytes

ABSTRACT: Cytotoxic T lymphocytes (CTL) kill malignant and infected cells via cytotoxic proteins such as granzyme B (GzmB) that are released into the immunological synapse in the form of ~110 nm supramolecular attack particles (SMAPs). However, it is not known where SMAPs are stored in the cell and how they are released. To address this, we utilized knock-in mice to label fusogenic cytotoxic granules with synaptobrevin2-mRFP. We identified two classes of fusion-competent granules, single core granules (SCG) and multi core granules (MCG), with different diameter, morphology, and protein composition. Functional analyses demonstrate that both classes of granules fuse with the plasma membrane at the IS. SCG fusion resulted in rapid dispersal of GzmB. MCG labelled with the SMAP marker thrombospondin-1 and their fusion events resulted in deposition of SMAPs. The CTL attack strategy thus includes SCG fusion to disperse immediately active cytotoxic proteins and parallel MCG fusion to deposit concentrated latent SMAPs onto the target.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Spleen, Cell Suspension Culture, T Cell

SUBMITTER: Momchil Ninov  

LAB HEAD: Henning Urlaub

PROVIDER: PXD025055 | Pride | 2022-04-04

REPOSITORIES: Pride