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Updated: Apr 18, 2026
Phenotypic and Functional Analysis of Activated Regulatory T Cells Isolated from Chronic Lymphocytic Choriomeningitis Virus-infected Mice
Published on: June 22, 2016
A transendocytosis model of CTLA-4 function predicts its suppressive behavior on regulatory T cells
Tie Zheng Hou1, Omar S Qureshi2, Chun Jing Wang1
1Division of Infection and Immunity, Department of Immunology, Institute of Immunity and Transplantation, University College London, Royal Free Hospital, London NW3 2PF, United Kingdom; and.
Abstract:
Manipulation of the CD28/CTLA-4 pathway is at the heart of a number of immunomodulatory approaches used in both autoimmunity and cancer. Although it is clear that CTLA-4 is a critical regulator of T cell responses, the immunological contexts in which CTLA-4 controls immune responses are not well defined. In this study, we show that whereas CD80/CD86-dependent activation of resting human T cells caused extensive T cell proliferation and robust CTLA-4 expression, in this context CTLA-4 blocking Abs had no impact on the response. In contrast, in settings where CTLA-4(+) cells were present as "regulators," inhibition of resting T cell responses was dependent on CTLA-4 expression and specifically related to the number of APC. At low numbers of APC or low levels of ligand, CTLA-4-dependent suppression was highly effective whereas at higher APC numbers or high levels of ligand, inhibition was lost. Accordingly, the degree of suppression correlated with the level of CD86 expression remaining on the APC. These data reveal clear rules for the inhibitory function of CTLA-4 on regulatory T cells, which are predicted by its ability to remove ligands from APC.
Insights
The CD28/CTLA-4 pathway regulates T cell responses. CTLA-4 (cytotoxic T-lymphocyte-associated protein 4) effectively suppresses T cells when regulatory cells are present, particularly with limited antigen-presenting cells (APCs).
Area of Science:
- Immunology
- Cellular Biology
- Molecular Medicine
Background:
- The CD28/CTLA-4 pathway is crucial for immunomodulation in autoimmunity and cancer.
- CTLA-4 (cytotoxic T-lymphocyte-associated protein 4) is a known regulator of T cell responses, but its precise functions in different immunological contexts remain unclear.
Purpose of the Study:
- To define the immunological contexts governing CTLA-4's inhibitory function.
- To elucidate the relationship between antigen-presenting cell (APC) numbers, ligand availability, and CTLA-4-mediated T cell suppression.
Main Methods:
- Investigated the impact of CTLA-4 blocking antibodies on human T cell activation.
- Assessed T cell proliferation and CTLA-4 expression under varying conditions of APC numbers and CD80/CD86 ligand levels.
Main Results:
- CD80/CD86-dependent activation of resting T cells led to proliferation and CTLA-4 expression, but CTLA-4 blocking antibodies had no effect in this setting.
- In the presence of regulatory T cells, CTLA-4-dependent suppression of resting T cells was observed and was dependent on APC numbers.
- Suppression efficacy decreased with higher APC numbers or ligand levels, correlating with remaining CD86 expression on APCs.
Conclusions:
- CTLA-4's inhibitory function on regulatory T cells is highly dependent on the availability of ligands on APCs.
- The ability of CTLA-4 to remove ligands from APCs predicts its suppressive capacity, providing clear rules for its function.
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