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Microvilli structures on B lymphocytes: inducible functional domains?
Gediminas Greicius1, Lisa Westerberg, Edward J Davey
1Department of Cell and Molecular Biology, Karolinska Institutet, 17177 Stockholm, Sweden.
International Immunology
|January 22, 2004
Summary
T cell signals like IL-4 induce B cell microvilli, which are specialized membrane domains. These microvilli help organize cell surface proteins, enhancing B cell-T cell interactions crucial for immune responses.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- B lymphocyte and T cell interaction is vital for immune responses.
- T cell signals (e.g., IL-4, CD40) drive B cell differentiation.
- Previous work linked these signals to B cell microvilli formation and adhesion.
Purpose of the Study:
- To investigate if IL-4 induces protein segregation into B cell microvilli and lipid rafts.
- To analyze the role of lipid rafts in microvilli formation and protein localization.
Main Methods:
- Immuno-electron microscopy to study cell-surface molecule distribution.
- Sucrose gradient centrifugation to analyze recruitment to detergent-resistant membrane fractions.
- Cholesterol depletion using beta-methyl-cyclodextrin to assess lipid raft dependence.
Main Results:
- Microvilli were enriched in ICAM-1 and MHC class II; LFA-1 and CD40 were on smooth surfaces; B7-2 was randomly distributed.
- Cholesterol depletion reduced microvilli, indicating lipid raft requirement.
- IL-4 stimulation, alongside LPS, led to GM(1) (lipid raft marker) enrichment on microvilli.
Conclusions:
- B cell microvilli are inducible membrane domains that segregate specific cell-surface receptors.
- Lipid rafts are essential for microvilli expression.
- Microvilli can regulate B-T cell interactions by organizing and presenting receptors in 3D.