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Acquisition of cytotoxic T lymphocyte-specific carbohydrate differentiation antigens
Abstract:
Cytotoxic T cell (CTL)-specific activation antigens, termed CT determinants, have been detected by monoclonal antibodies (mAb) that inhibit CTL function. At the cell surface, the CT antigens are associated with the T200 glycoproteins and two other proteins of Mr 140,000 and 85,000 and are present on a secreted protein, gp155. Periodate treatment followed by binding analysis and immunoprecipitation experiments using tunicamycin-treated cells indicated that carbohydrate is necessary for CT antigen expression. Furthermore, gp155 is secreted in the presence of tunicamycin while retaining the CT antigens, and the CT determinants are added late in T200 biosynthesis, suggesting that the CT glycans are O-linked. Finally, interleukin 2 was shown to dramatically influence the expression of the CT mAb-reactive oligosaccharides present at the CTL cell surface.
Insights
Cytotoxic T cell (CTL) activation antigens require specific carbohydrates for expression, suggesting O-linked glycosylation. Interleukin 2 significantly impacts these crucial cell surface markers.
Area of Science:
- Immunology
- Molecular Biology
- Glycobiology
Background:
- Cytotoxic T lymphocytes (CTLs) play a critical role in adaptive immunity.
- CTL-specific activation antigens (CT determinants) are recognized by monoclonal antibodies (mAbs) that can inhibit CTL function.
- These CT antigens are cell surface molecules involved in immune cell recognition and signaling.
Purpose of the Study:
- To investigate the molecular nature and biosynthesis of CT determinants.
- To determine the role of carbohydrates in CT antigen expression.
- To elucidate the influence of cytokines, such as interleukin 2, on CT antigen presentation.
Main Methods:
- Monoclonal antibody (mAb) binding assays.
- Periodate treatment to assess carbohydrate involvement.
- Immunoprecipitation experiments with tunicamycin-treated cells.
- Analysis of protein association and secretion.
- Assessment of interleukin 2 effects on oligosaccharide expression.
Main Results:
- CT antigens are associated with T200 glycoproteins and other cell surface proteins, as well as a secreted protein gp155.
- Carbohydrate moieties are essential for CT antigen expression, as indicated by periodate treatment and tunicamycin experiments.
- gp155 retains CT antigens upon secretion even with tunicamycin treatment, and CT determinants are added late in T200 biosynthesis, suggesting O-linked glycosylation.
- Interleukin 2 significantly modulates the expression of CT mAb-reactive oligosaccharides on the CTL surface.
Conclusions:
- CT antigen expression is critically dependent on specific O-linked glycans.
- The biosynthesis of CT antigens involves late-stage glycosylation events.
- Interleukin 2 is a key regulator of CT antigen presentation, influencing immune responses.