Journal of Leukocyte Biology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
QUICK SEARCH:   [advanced]


     

A more recent version of this article appeared on January 1, 2007

Published online before print October 6, 2006
This Article
Right arrow Full Text (Reprint (PDF))
Right arrow All Versions of this Article:
jlb.1105692v1
81/1/284    most recent
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Nan, X.
Right arrow Articles by Stamatos, N. M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Nan, X.
Right arrow Articles by Stamatos, N. M.
© by The Society for Leukocyte Biology
Journal of Leukocyte Biology, doi:10.1189/jlb.1105692

Received for publication November 27, 2005.
Revised August 30, 2006.
Accepted for publication September 11, 2006.

Article

Sialidase expression in activated human T lymphocytes influences production of IFN-{gamma}

Xinli Nan *, Ivan Carubelli *, and Nicholas M. Stamatos *{dagger}@

*Institute of Human Virology, University of Maryland, Baltimore, Maryland, USA; and {dagger}Division of Infectious Diseases, Department of Medicine, University of Maryland Medical Center, Baltimore, Maryland, USA

@ To whom correspondence should be addressed. E-mail: stamatos{at}umbi.umd.edu.


  Abstract

Sialidases influence cellular activity by removing terminal sialic acid from glycoproteins and glycolipids. Four genetically distinct sialidases (Neu1-4) have been identified in mammalian cells. In this study, we demonstrate that only lysosomal Neu1 and plasma membrane-associated Neu3 are detected in freshly isolated and activated human T lymphocytes. Activation of lymphocytes by exposure to anti-CD3 and anti-CD28 IgG resulted in a ninefold increase in Neu1-specific activity after growth of cells in culture for 5 days. In contrast, the activity of Neu3 changed minimally in activated lymphocytes. The increase in Neu1 enzyme activity correlated with increased synthesis of Neu1-specific mRNA. Neu1 was present on the surface of freshly isolated and activated CD4 and CD8 T lymphocytes, as determined by staining intact cells with anti-Neu1 IgG and analysis by flow cytometry and by Western blot analysis of biotin-labeled cell surface proteins. Cell surface Neu1 was found tightly associated with a subunit of protective protein cathepsin A. Compared with freshly isolated lymphocytes, activated cells expressed more surface-binding sites for galactose-recognizing lectins Erythrina cristagalli (ECA) and Arachis hypogaea. Growth of cells in the presence of sialidase inhibitors 2,3-dehydro-2-deoxy-N-acetylneuraminic acid or 4-guanidino-2-deoxy-2,3-dehydro-N- acetylneuraminic acid resulted in a smaller increase in number of ECA-binding sites and a greater amount of cell surface sialic acid in activated cells. Inhibition of sialidase activity also resulted in reduced expression of IFN-{gamma} in activated cells. The down-regulation of IFN-{gamma} occurred at the transcriptional level. Thus, sialidase activity in activated T lymphocytes contributes to the hyposialylation of specific cell surface glycoconjugates and to the production of IFN-{gamma}.

Key Words: activation • sialic acid • cytokines






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
Copyright © 2006 by the Society for Leukocyte Biology.