Increased cystatin F levels correlate with decreased cytotoxicity of cytotoxic T cells
Article Category: Research Article
Published Online: Mar 03, 2019
Page range: 57 - 68
Received: Dec 08, 2018
Accepted: Jan 05, 2019
DOI: https://doi.org/10.2478/raon-2019-0007
© 2019 Mateja Prunk, Milica Perisic Nanut, Jerica Sabotic, Urban Svajger, Janko Kos, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
Background
Cystatin F is a protein inhibitor of cysteine peptidases, expressed predominantly in immune cells and localised in endosomal/lysosomal compartments. In cytotoxic immune cells cystatin F inhibits both the major pro-granzyme convertases, cathepsins C and H that activate granzymes, and cathepsin L, that acts as perforin activator. Since perforin and granzymes are crucial molecules for target cell killing by cytotoxic lymphocytes, defects in the activation of either granzymes or perforin can affect their cytotoxic potential.
Materials and methods
Levels of cystatin F were assessed by western blot and interactions of cystatin F with cathepsins C, H and L were analysed by immunoprecipitation and confocal microscopy. In TALL-104 cells specific activities of the cathepsins and granzyme B were determined using peptide substrates.
Results
Two models of reduced T cell cytotoxicity of TALL-104 cell line were established, either by treatment by ionomycin or by immunosuppressive transforming growth factor beta. Reduced cytotoxicity correlated with increased levels of cystatin F and with attenuated activities of cathepsins C, H and L and of granzyme B. Co-localisation of cystatin F and cathepsins C, H and L and interactions between cystatin F and cathepsins C and H were demonstrated.
Conclusions
Cystatin F is designated as a possible regulator of T cell cytotoxicity, similar to its role in natural killer cells.