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Stimulator cell type influences the response of T cells to staphylococcal enterotoxins
J Yagi1, T Uchiyama, C A Janeway
1Department of Microbiology and Immunology, Tokyo Women's Medical College, Japan.
Abstract:
Responses to the superantigen Mls are characterized by proliferation of a significant percentage of T cells expressing receptors encoded by one or a few V beta gene segments. Apparently similar responses are elicited by the staphylococcal enterotoxins (SEs) and other bacterial superantigens. We have observed that T cells can be stimulated by the bacterial superantigen SEs presented by either spleen cells or fibroblasts transfected with the appropriate MHC class II genes. However, the results in this study showed that T cells required more than 100-fold higher concentrations of SEA in the presence of L cell transfectants than spleen APC, although T cell responses to SEB and several other toxins presented by the two types of APC were equivalent. Thus, L cell transfectants have a selective defect in presenting SEA. These data suggest that fibroblasts lack a component required by SEA to stimulate certain T cells, and lead us to propose an alternative model for bacterial superantigen mitogenesis in which the superantigen binds to and modifies the behavior of an endogenous co-ligand.
Insights
Bacterial superantigens like staphylococcal enterotoxins (SEs) activate T cells. Fibroblast cells show a defect in presenting SEA, suggesting a missing co-ligand is needed for T cell stimulation.
Area of Science:
- Immunology
- Microbiology
Background:
- Bacterial superantigens, such as staphylococcal enterotoxins (SEs), induce T cell proliferation.
- T cell receptor (V beta) usage is restricted during superantigen responses.
Purpose of the Study:
- To investigate the antigen-presenting cell (APC) requirements for bacterial superantigen-mediated T cell stimulation.
- To identify potential differences in the presentation of staphylococcal enterotoxin A (SEA) by various APCs.
Main Methods:
- T cell stimulation assays using spleen cells and L cell transfectants expressing MHC class II.
- Comparison of T cell responses to different staphylococcal enterotoxins (SEs) presented by distinct APCs.
Main Results:
- T cells were stimulated by SEs presented by both spleen cells and transfected fibroblasts.
- Fibroblasts required over 100-fold higher concentrations of SEA compared to spleen APCs for T cell stimulation.
- T cell responses to SEB and other SEs were equivalent between spleen cells and fibroblasts.
Conclusions:
- Fibroblasts exhibit a selective defect in presenting SEA, indicating a lack of a crucial component for SEA-mediated T cell activation.
- A model is proposed where superantigens bind and modify an endogenous co-ligand, influencing T cell activation.