Volume 50, Issue 10 pp. 3211-3220
Research Article

Involvement of inducible costimulator in the exaggerated memory B cell and plasma cell generation in systemic lupus erythematosus

Andreas Hutloff

Andreas Hutloff

Robert Koch Institute, Berlin, Germany

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Kerstin Büchner

Kerstin Büchner

Robert Koch Institute, Berlin, Germany

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Karin Reiter

Karin Reiter

University Hospital Charité, Berlin, Germany

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Hans J. Baelde

Hans J. Baelde

Leiden University Medical Center, Leiden, The Netherlands

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Marcus Odendahl

Marcus Odendahl

University Hospital Charité, Berlin, Germany

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Annett Jacobi

Annett Jacobi

University Hospital Charité, Berlin, Germany

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Thomas Dörner

Thomas Dörner

University Hospital Charité, Berlin, Germany

Drs. Dörner and Kroczek contributed equally to this work.

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Richard A. Kroczek

Corresponding Author

Richard A. Kroczek

Robert Koch Institute, Berlin, Germany

Drs. Dörner and Kroczek contributed equally to this work.

Molecular Immunology, Robert Koch Institute, Nordufer 20, D-13353 Berlin, GermanySearch for more papers by this author
First published: 08 October 2004
Citations: 167

Abstract

Objective

In systemic lupus erythematosus (SLE), the increased generation of memory B cells and plasma cells leads to autoimmune hypergammaglobulinemia and destructive immunoglobulin deposits in the kidneys. We undertook this study to determine the biologic mechanism driving this overactivation of the B cell compartment, which is the central issue in SLE.

Methods

We used flow cytometry to analyze expression of the T cell–specific inducible costimulator (ICOS) and its ligand (ICOS-L) on B cells obtained from the peripheral blood of SLE patients. We correlated ICOS-L expression with the differentiation status of the B cells using a large panel of surface antigens. In addition, SLE kidneys were analyzed by immunohistology.

Results

We found an increased expression of ICOS on CD4+ as well as CD8+ T cells in SLE. At the same time, we documented a down-regulation of ICOS-L on a high proportion of peripheral blood memory B cells. Based on in vitro experiments, we inferred that this ICOS-L down-regulation on B cells was a signature of recent interaction with ICOS+ T cells in vivo. In the kidneys of SLE patients, we found clusters of B cells and plasma cells in close contact with ICOS+ T cells.

Conclusion

Detailed analysis of B cells with down-regulated ICOS-L suggests that ICOS is one of the forces driving the formation of memory B cells and plasma cells in SLE. Furthermore, our identification of plasma cells in areas of T cell–B cell interaction in kidneys suggests that components of a T cell–driven B cell activation process may take place in peripheral tissues in SLE.

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