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Murine B1 B cells require IL-5 for optimal T cell-dependent activation
L D Erickson1, T M Foy, T J Waldschmidt
1Department of Pathology and Immunology Graduate Program, University of Iowa College of Medicine, Iowa City, IA 52242, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|February 13, 2001
Summary
Murine B cell activation differs by subset. While most B cells need CD40-CD40L interactions and IL-4, B1 cells utilize IL-5 and can respond independently, explaining immune responses in certain deficiencies.
Area of Science:
- Immunology
- Cell Biology
Background:
- T helper cell activation of B cells typically relies on CD40-CD40 ligand (CD40L) and specific cytokines.
- Previous studies focused on conventional splenic B cells, leaving the responses of other B cell subsets unclear.
Purpose of the Study:
- To investigate the differential dependence of various murine B cell subsets on CD40-CD40L interactions and T cell-derived cytokines.
- To compare the activation requirements of splenic follicular, marginal zone, peritoneal B2, and B1 B cells.
Main Methods:
- Sort purification of splenic and peritoneal B cell subsets based on CD23 expression.
- Culture of purified B cells with recombinant CD40L and cytokines or with T helper 2 (Th2) cells.
Main Results:
- Follicular, marginal zone, and peritoneal B2 B cells require CD40-CD40L and IL-4 for optimal activation, proliferation, differentiation, and isotype switching.
- Peritoneal B1 B cells use IL-5 with CD40-CD40L for maximal T cell-dependent responses.
- B1 B cells exhibit CD40-CD40L-independent activation, proliferation, differentiation, and isotype switching, mediated by IL-4 and IL-5.
Conclusions:
- B cell activation pathways vary significantly among different B cell subsets.
- The unique CD40-CD40L-independent response of B1 B cells, driven by IL-4 and IL-5, may account for residual antibody responses in CD40L/CD40-deficient individuals and X-linked hyper-IgM patients.