scholarly journals The CD4 molecule is not always required for the T cell response to bacterial enterotoxins.

1991 ◽  
Vol 173 (2) ◽  
pp. 367-371 ◽  
Author(s):  
R P Sékaly ◽  
G Croteau ◽  
M Bowman ◽  
P Scholl ◽  
S Burakoff ◽  
...  
Keyword(s):  
T Cell ◽  
Mhc Class Ii ◽  
T Cell Activation ◽  
Cell Response ◽  
Cell Activation ◽  
Interleukin 2 ◽  
Class Ii ◽  
T Cell Response ◽  
Cd4 Cells ◽  
Mhc Class Ii Molecules

T cells respond in a V beta-restricted fashion to bacterial enterotoxins bound to major histocompatibility complex (MHC) class II molecules. The requirement for CD4 in MHC class II-restricted T cell responses is very well established. We have assessed the role of CD4 in the T cell response to the bacterial enterotoxins Staphylococcal enterotoxin A (SEA), SEB, and toxic shock syndrome toxin 1. Three CD4- murine T cell hybridomas were transfected with the human CD4 molecule and assayed for interleukin 2 production in the presence of accessory cells bearing human MHC class II molecules and of the appropriate enterotoxin. The results clearly indicate that CD4- cells responded even to suboptimal concentrations of enterotoxin(s) equally well as CD4+ cells. Furthermore, expression of CD4 did not result in the acquisition of previously undetectable reactivity to enterotoxins. These results suggest that unlike the case with antigen-specific responses, formation of a T cell receptor-CD3/CD4 supramolecular complex is not always essential for T cell activation by bacterial enterotoxins.

Responding naive T cells differ in their sensitivity to Fas engagement: early death of many T cells is compensated by costimulation of surviving T cells

Blood ◽  
2003 ◽  
Vol 101 (10) ◽  
pp. 4022-4028 ◽  
Author(s):  
Mikael Maksimow ◽  
Minna Santanen ◽  
Sirpa Jalkanen ◽  
Arno Hänninen
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Response ◽  
Cell Activation ◽  
Interleukin 2 ◽  
Early Death ◽  
T Cell Response ◽  
Naive T Cells ◽  
Naïve T Cells

Abstract Engagement of Fas (CD95) induces death of activated T cells but can also potentiate T-cell response to CD3 ligation. Yet, the effects of Fas-mediated signals on activation of naive T cells have remained controversial. We followed naive T cells responding under Fas ligation. Ligation of Fas simultaneously with activation by antigen-bearing dendritic cells promoted early death in half of the responding naive murine CD4 T cells. Surprisingly, it simultaneously accelerated cell division and interferon-γ (IFN-γ) production among surviving T cells. These cells developed quickly an activation-associated phenotype (CD44hi, CD62Llo), responded vigorously to antigen rechallenge, were partially resistant to subsequent induction of cell death via Fas, and were long-lived in vivo. Compared with cells becoming apoptotic, the surviving cells expressed lower levels of Fas and higher levels of T-cell receptor (TCR), CD4, and interleukin-2 receptor (IL-2R). Their survival was associated with expression of antiapoptotic cellular FLICE-inhibitory protein (c-FLIP), Bcl-XL, and Bcl-2. Thus, at the time of T-cell activation there is a subtle balance in the effects of Fas ligation that differs on a cell-to-cell basis. Factors that predict cell survival include expression levels of Fas, TCR, CD4, and IL-2R. Early death of some cells and a pronounced response of the surviving cells suggest that Fas ligation can both up- and down-regulate a primary T-cell response.

scholarly journals Activation of Human T Cells by Major Histocompatability Complex Class II Expressing Neutrophils: Proliferation in the Presence of Superantigen, But Not Tetanus Toxoid

Blood ◽  
1997 ◽  
Vol 89 (11) ◽  
pp. 4128-4135 ◽  
Author(s):  
Neil A. Fanger ◽  
Chunlei Liu ◽  
Paul M. Guyre ◽  
Kathleen Wardwell ◽  
Jerome O'Neil ◽  
...  
Keyword(s):  
T Cell ◽  
Mhc Class Ii ◽  
T Cell Activation ◽  
Tetanus Toxoid ◽  
Cell Activation ◽  
Class Ii ◽  
Polymorphonuclear Neutrophils ◽  
Gm Csf ◽  
Ifn Γ ◽  
Mhc Class Ii Molecules

Abstract The primary function of polymorphonuclear neutrophils (PMN) in the immune response appears to be acute phagocytic clearance of foreign pathogens and release of inflammatory mediators. Consistent with their assumed lack of major histocompatibility complex (MHC) class II expression, PMN have not been considered to play a role in antigen presentation and T-cell activation. However, recent reports have shown that human PMN can express MHC class II molecules both in vitro and in vivo after stimulation with either granulocyte-macrophage colony-stimulating factor (GM-CSF ) or interferon-γ (IFN-γ). Thus, under appropriate conditions, PMN could play a significant role in immune regulation, including T-cell activation. In this report, we demonstrate that human class II–expressing PMN can serve as accessory cells in superantigen (SAg)-mediated T-cell activation. This accessory activity for SAg presentation was present only after induction of MHC class II expression, and was especially pronounced following culture of PMN with GM-CSF plus IFN-γ, which acted synergistically to induce MHC class II molecules on PMN. Moreover, the level of MHC class II expression and the magnitude of SAg-induced T-cell responses were found to be highly correlated and distinctly donor dependent, with PMN from some donors repeatedly showing fivefold higher responses than PMN from other donors. On the other hand, culture of PMN with GM-CSF plus IFN-γ under conditions that resulted in optimal MHC class II expression did not enable them to function as antigen-presenting cells for either intact tetanus toxoid (TT) or for a TT peptide. These results delineate a new pathway for T-cell activation by SAg that may play an important role in the severity of SAg-induced inflammatory responses. They also identify a donor-specific polymorphism for induction of PMN MHC class II expression which may be of significance for therapies involving GM-CSF and IFN-γ.

Decreased expression of MHC class II and cathepsin E in dendritic cells might contribute to impaired induction of antigen-specific T cell response in NC/Nga mice

2012 ◽  
Vol 59 (1,2) ◽  
pp. 95-101 ◽  
Author(s):  
Tohru Sakai ◽  
Emi Shuto ◽  
Tomoyo Taki ◽  
Honami Imamura ◽  
Miku Kioka ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
T Cell ◽  
Mhc Class Ii ◽  
Cell Response ◽  
Class Ii ◽  
T Cell Response ◽  
Cathepsin E
Sign in / Sign up

Export Citation Format

Share Document