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Functional expression of B7/BB1 on activated T lymphocytes
M Azuma1, H Yssel, J H Phillips
1DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, California 94304.
The Journal of Experimental Medicine
|March 1, 1993
Summary
Activated T cells express B7, a molecule that binds to CD28, potentially enabling T cells to costimulate themselves through an autocrine pathway. This finding impacts understanding of T cell activation and immune responses.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- B7/BB1 is a known costimulatory molecule binding CD28 on T cells, crucial for T cell activation.
- This interaction enhances T cell responses initiated by the CD3/T cell receptor complex.
Purpose of the Study:
- To investigate the expression of B7 on activated human T cells.
- To determine if activated T cells can provide costimulatory signals to other T cells.
Main Methods:
- Flow cytometry to detect B7 expression on various activated immune cells.
- Immunoprecipitation of labeled activated T cells to confirm B7 presence.
- Detection of B7 gene transcripts.
- Mixed lymphocyte response assays using T cell clones.
Main Results:
- B7 was found to be expressed on activated human peripheral blood T cells, including CD4+, CD8+, and natural killer cell clones.
- B7 expression on T cells appears later in the activation process and is present on antigen-specific T cell clones.
- An activated B7+ CD4+ T cell clone could stimulate allogeneic T cells, with responses partially inhibited by anti-B7 antibodies.
Conclusions:
- Activated T cells can express B7, a molecule typically found on antigen-presenting cells.
- The coexpression of CD28 and B7 on activated T cells suggests a potential for autocrine T cell costimulation.
- This autocrine signaling may play a role in regulating T cell proliferation and cytokine production.