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Early steps of IgA B cell differentiation.
W Strober1, G R Harriman, D R Kunimoto
1Mucosal Immunity Section, LCI, National Institute of Allergy and Infectious Diseases, Bethesda, Md.
Immunologic Research
|January 1, 1991
Summary
Virgin B cells in Peyer's patches initiate IgA differentiation via a microenvironment. Subsequent stages involve dual sIgM/sIgA expression and committed IgA B cells responding to terminal factors.
Area of Science:
- Immunology
- Cell Biology
Background:
- Peyer's patches are crucial inductive sites for mucosal immunity.
- B cell differentiation into IgA-producing plasma cells is vital for mucosal defense.
Purpose of the Study:
- To elucidate the sequential steps of IgA B cell differentiation within Peyer's patches.
- To identify the microenvironmental factors and cellular intermediates involved in IgA isotype switching.
Main Methods:
- Analysis of B cell populations within Peyer's patches.
- Characterization of surface immunoglobulin (sIg) and mRNA expression during differentiation.
Main Results:
- Initial IgA switch differentiation occurs in sIgM+ B cells, likely mediated by stromal cells, independent of TGF-beta.
- A transitional stage with co-expressed sIgM and sIgA, producing C mu and C alpha mRNA, was observed.
- Committed IgA B cells emerge, expressing only sIgA, and can migrate to respond to terminal differentiation factors like IL-5, IL-6, and IFN-gamma.
Conclusions:
- Peyer's patch microenvironment drives primary IgA differentiation.
- A novel intermediate B cell stage with dual sIgM/sIgA expression exists.
- Sequential differentiation leads to committed IgA B cells capable of terminal differentiation.