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Activation of T cells by superantigen in class II-negative mice
A C Avery1, J S Markowitz, M J Grusby
1Department of Pathology, Harvard Medical School, Dana-Farber Cancer Institute, Boston, MA.
Abstract:
The ability of the staphylococcal enterotoxins to stimulate T cells has been thought to depend on their association with class II MHC products. Here, we demonstrate that a subgroup of staphylococcal enterotoxins, which includes staphylococcal enterotoxin C and staphylococcal enterotoxin E, stimulates strong MHC-independent responses, thereby resulting in T cell expansion and generation of CTL. The immunologic consequences of MHC-independent activation of T cells by superantigens differ from those of class II-dependent activation, inasmuch as this pathway does not result in detectable T cell deletion. These findings delineate a novel MHC-independent T cell activation pathway that leads to both clonal expansion and expression of CTL effector function in response to a subgroup of bacterial superantigens.
Insights
Certain staphylococcal enterotoxins activate T cells independently of MHC class II, promoting T cell expansion and cytotoxic T lymphocyte (CTL) generation without T cell deletion. This reveals a new superantigen activation pathway.
Area of Science:
- Immunology
- Microbiology
- Molecular Biology
Background:
- Staphylococcal enterotoxins (SEs) are potent immune activators.
- T cell stimulation by SEs was traditionally believed to require interaction with MHC class II molecules.
Purpose of the Study:
- To investigate the mechanism of T cell activation by a specific subgroup of SEs.
- To determine if MHC class II is essential for SE-induced T cell responses.
Main Methods:
- Utilized staphylococcal enterotoxin C (SEC) and staphylococcal enterotoxin E (SEE) in T cell activation assays.
- Assessed T cell expansion and cytotoxic T lymphocyte (CTL) generation.
- Compared MHC-dependent and MHC-independent activation pathways.
Main Results:
- Demonstrated that SEC and SEE can stimulate strong T cell responses independently of MHC class II.
- Observed significant T cell expansion and generation of CTLs via this MHC-independent pathway.
- Found no detectable T cell deletion in MHC-independent activation, unlike MHC-dependent pathways.
Conclusions:
- Identified a novel MHC-independent T cell activation pathway induced by a subgroup of bacterial superantigens.
- This pathway leads to clonal T cell expansion and effector CTL function.
- Highlights distinct immunologic consequences between MHC-dependent and independent superantigen activation.