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Recently activated T cells are costimulation-dependent in vitro.
F M Marelli-Berg1, O Barroso-Herrera, R I Lechler
1Department of Immunology, Imperial College School of Medicine at the Hammersmith Hospital, London, W12 0NN, United Kingdom.
Cellular Immunology
|August 6, 1999
Summary
Primed T cells still require B7 costimulation for immune response amplification. Without B7, T cells become unresponsive, but this state can be reversed with IL-2.
Area of Science:
- Immunology
- Cellular immunology
- T cell activation
Background:
- B7-mediated signaling is crucial for naive T cell activation.
- The role of costimulation in amplifying initiated immune responses remains unclear.
Purpose of the Study:
- Investigate costimulation requirements for recently activated alloreactive CD4(+) T cells.
- Determine the outcome of allorecognition of B7-deficient epithelial cells.
Main Methods:
- Developed a multistep in vitro culture system.
- Used allogeneic costimulation-rich antigen-presenting cells for priming.
- Examined T cell reactivation upon encountering B7-deficient cells.
Main Results:
- Primed T cells require B7 costimulation for reactivation and proliferation.
- Recognition of antigen on B7-negative cells induced allospecific nonresponsiveness.
- Nonresponsiveness was reversible with IL-2, without IL-4 secretion.
Conclusions:
- "Primed" T cells remain B7-dependent in vitro.
- Costimulation-deficient antigen presentation can lead to functional inactivation of primed T cells.