HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Laforge, M. Articles by Senik, A. Search for Related Content PubMed PubMed Citation Articles by Laforge, M. Articles by Senik, A.

Apoptotic Death Concurrent with CD3 Stimulation in Primary Human CD8⁺ T Lymphocytes: A Role for Endogenous Granzyme B¹

Laboratoire de Greffes d’Epithéliums et Régulation de l’Activation Lymphocytaire, Unité 542, Institut National de la Santé et de la Recherche Médicale, Hôpital Paul Brousse, Villejuif, France

We exposed primary CD8⁺ T cells to soluble CD3 mAb plus IL-2 and limited numbers of monocytes (3%). These cells were activated but concurrently subjected to ongoing apoptosis (25% were apoptotic from day 2 of culture). However, their costimulated CD4⁺ counterparts were much less prone to apoptosis. The apoptotic signaling pathway bypassed Fas and TNFRs, and required the activity of cathepsin C, a protease which performs the proteolytic maturation of granzyme (Gr) A and GrB proenzymes within the cytolytic granules. Silencing the GrB gene by RNA interference in activated CD8⁺ T cells prevented the activation of procaspase-3 and Bid, and indicated that GrB was the upstream death mediator. A GrB-specific mAb immunoprecipitated a 70-kDa molecular complex from cytolytic extracts of activated CD8⁺ (but not resting) T cells, that was specifically recognized by a nucleocytoplasmic protease inhibitor 9 (PI-9) specific mAb. This complex was also detected after reciprocal immunoprecipitation of PI-9. It coexisted in the cytosol with the 32-kDa form of GrB. As neither were detected in the cytosol of CD4⁺ bystander T cells (which poorly synthesized GrB), and as silencing the perforin (Pf) gene had no effect in our system, endogenous GrB was likely implicated. Immunoprecipitation experiments failed to reveal Pf in the cytosol of CD8⁺ T cells, and only a tiny efflux of granular GrA was detected by ELISA. We propose that some GrB is released from cytolytic granules to the cytosol of CD8⁺ T lymphocytes upon CD3/TCR stimulation and escapes PI-9, thereby mediating apoptotic cell death.

This article has been cited by other articles:

				V. Mateo, M. Menager, G. de Saint-Basile, M.-C. Stolzenberg, B. Roquelaure, N. Andre, B. Florkin, F. le Deist, C. Picard, A. Fischer, et al. Perforin-dependent apoptosis functionally compensates Fas deficiency in activation-induced cell death of human T lymphocytes Blood, December 15, 2007; 110(13): 4285 - 4292. [Abstract] [Full Text] [PDF]

				B. Z. Packard, W. G. Telford, A. Komoriya, and P. A. Henkart Granzyme B Activity in Target Cells Detects Attack by Cytotoxic Lymphocytes J. Immunol., September 15, 2007; 179(6): 3812 - 3820. [Abstract] [Full Text] [PDF]