Related Experiment Videos
Functional responses and costimulator dependence of memory CD4+ T cells
C A London1, M P Lodge, A K Abbas
1Immunology Research Division, Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA. calondon@ucdavis.edu
Journal of Immunology (Baltimore, Md. : 1950)
|December 22, 1999
Summary
Memory CD4+ T cells mount rapid recall responses to antigens, producing effector cytokines quickly without extensive cell division. These memory cells require less stimulation and are resistant to tolerance induction, indicating a lower activation threshold.
Area of Science:
- Immunology
- Cellular immunology
Background:
- Memory CD4+ T cells are crucial for adaptive immunity.
- Understanding their activation threshold is key to predicting secondary immune responses.
Purpose of the Study:
- To compare the functional characteristics of memory CD4+ T cells with naive CD4+ T cells.
- To investigate the activation requirements and effector functions of memory T cells in vivo.
Main Methods:
- Adoptive transfer system to generate Ag-specific memory and naive CD4+ T cells in mice.
- Comparison of cellular localization, recall responses, cytokine production, proliferation, costimulation dependency, and tolerance induction between memory and naive cells.
Main Results:
- Memory CD4+ T cells exhibited rapid recall responses and localized to lymphoid organs.
- They produced effector cytokines (IFN-gamma, IL-4, IL-5) within 12-24 hours without multiple cell divisions.
- Memory cells proliferated at lower Ag concentrations, were less dependent on B7 and CD40 costimulation, and resisted tolerance induction.
Conclusions:
- Memory CD4+ T cells possess a lower activation threshold compared to naive cells.
- This facilitates rapid effector function during secondary immune responses, even with low antigen and costimulation levels.