Open Access Research

Effector granules in human T lymphocytes: the luminal proteome of secretory lysosomes from human T cells

Hendrik Schmidt1, Christoph Gelhaus2, Melanie Nebendahl1, Marcus Lettau1, Ralph Lucius3, Matthias Leippe2, Dietrich Kabelitz1 and Ottmar Janssen1*

Author Affiliations

1 Institute of Immunology, Christian-Albrechts-University, UK S-H Campus Kiel, Kiel, Germany

2 Department of Zoophysiology, Zoological Institute, Christian-Albrechts-University, Kiel, Germany

3 Institute of Anatomy, Christian-Albrechts-University, Kiel, Germany

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Cell Communication and Signaling 2011, 9:4  doi:10.1186/1478-811X-9-4

Published: 21 January 2011

Abstract

Background

Cytotoxic cells of the immune system have evolved a lysosomal compartment to store and mobilize effector molecules. In T lymphocytes and NK cells, the death factor FasL is one of the characteristic marker proteins of these so-called secretory lysosomes, which combine properties of conventional lysosomes and exocytotic vesicles. Although these vesicles are crucial for immune effector function, their protein content in T cells has so far not been investigated in detail.

Results

In the present study, intact membranous vesicles were enriched from homogenates of polyclonally activated T cells and initially characterized by Western blotting and electron microscopic inspection. The vesicular fraction that contained the marker proteins of secretory lysosomes was subsequently analyzed by 2D electrophoresis and mass spectrometry. The proteome analysis and data evaluation revealed that 70% of the 397 annotated proteins had been associated with different lysosome-related organelles in previous proteome studies.

Conclusion

We provide the first comprehensive proteome map of T cell-derived secretory lysosomes with only minor contaminations by cytosolic, nuclear or other proteins. This information will be useful to more precisely address the activation-dependent maturation and the specific distribution of effector organelles and proteins in individual T or NK cell populations in future studies.