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Activated B cells express CD28/B7-independent costimulatory activity
1Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|August 15, 1996
Summary
Activated B cells provide T cell costimulation independent of the CD28/B7 pathway. This novel pathway, triggered by CD40 or LPS activation, enhances T cell proliferation, even in CD28-deficient mice.
Area of Science:
- Immunology
- Cell Biology
Background:
- Resting B cells are poor accessory cells, while activated B cells can trigger T cell activation.
- The B7 family molecules are thought to be key drivers of this functional switch in B cells.
Purpose of the Study:
- To investigate a novel costimulatory activity for T cell proliferation in activated B cells.
- To determine if this activity is independent of the CD28/B7 costimulatory pathway.
Main Methods:
- Comparing the capacity of B cells activated by different stimuli to activate CD4+ T cells from CD28-deficient mice.
- Assessing the expression of costimulatory and adhesion molecules (B7-1, B7-2, HSA, ICAM-1).
Main Results:
- B cells activated via CD40, and to a lesser extent LPS, exhibited potent B7/CD28-independent costimulatory activity.
- This activity significantly augmented IL-2-mediated proliferation of CD4+ T cells from CD28-deficient mice.
- Naive CD4+ T cells from CD28-deficient mice responded vigorously to costimulation from CD40L-activated B cells.
Conclusions:
- B cell activation induces a novel costimulatory pathway for T cell proliferation, independent of CD28/B7.
- This pathway is capable of activating naive CD4+ T cells, highlighting a new mechanism in immune cell interactions.