Lytic versus stimulatory synapse in cytotoxic T lymphocyte/target cell interaction: manifestation of a dual activation threshold.
Activation of biological functions in T lymphocytes is determined by the molecular dynamics occurring at the T cell/opposing cell interface. In the present study, a central question of cytotoxic T lymphocyte (CTL) biology was studied at the single-cell level: can two distinct activation thresholds for cytotoxicity and cytokine production be explained by intercellular molecular dynamics between CTLs and targets? In this study, we combine morphological approaches with numerical analysis, which allows us to associate specific patterns of calcium mobilization with different biological responses. We show that CTLs selectively activated to cytotoxicity lack a mature immunological synapse while exhibiting a low threshold polarized secretion of lytic granules and spike-like patterns of calcium mobilization. This finding is contrasted by fully activated CTLs, which exhibit a mature immunological synapse and smooth and sustained calcium mobilization. Our results indicate that intercellular molecular dynamics and signaling characteristics allow the definition of two activation thresholds in individual CTLs: one for polarized granule secretion (lytic synapse formation) and the other for cytokine production (stimulatory synapse formation).
Faroudi
Mustapha
M
Lymphocyte Interaction Group, Institut Claude de Préval, Institut National de la Santé et de la Recherche Médicale U563, 31059 Toulouse, France.
Utzny
Clemens
C
Salio
Mariolina
M
Cerundolo
Vincenzo
V
Guiraud
Martine
M
Müller
Sabina
S
Valitutti
Salvatore
S
D020013:Calcium Signaling; D002448:Cell Adhesion / Q000276:immunology; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology; D016764:Cell Polarity; D016207:Cytokines / Q000096:biosynthesis; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007365:Intercellular Junctions / Q000276:immunology; D007371:Interferon-gamma / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000096:biosynthesis; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D022142:Secretory Vesicles / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000502:physiology
D016207:Cytokines; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin; D007371:Interferon-gamma