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J Clin Invest. 2004 Oct;114(7):979-87.

Costimulation controls diabetes by altering the balance of pathogenic and regulatory T cells.

Author information

1
UCSF Diabetes Center, University of California at San Francisco, San Francisco, California 94143, USA.

Abstract

The development of autoimmune diabetes in the nonobese diabetic (NOD) mouse results from a breakdown in tolerance to pancreatic islet antigens. CD28-B7 and CD40 ligand-CD40 (CD40L-CD40) costimulatory pathways affect the development of disease and are promising therapeutic targets. Indeed, it was shown previously that diabetes fails to develop in NOD-B7-2-/- and NOD-CD40L-/- mice. In this study, we examined the relative role of these 2 costimulatory pathways in the balance of autoimmunity versus regulation in NOD mice. We demonstrate that initiation but not effector function of autoreactive T cells was defective in NOD-B7-2-/- mice. Moreover, the residual proliferation of the autoreactive cells was effectively controlled by CD28-dependent CD4+CD25+ regulatory T cells (Treg's), as depletion of Treg's partially restored proliferation of autoreactive T cells and resulted in diabetes in an adoptive-transfer model. Similarly, disruption of the CD28-B7 pathway and subsequent Treg deletion restored autoimmunity in NOD-CD40L-/- mice. These results demonstrate that development of diabetes is dependent on a balance of pathogenic and regulatory T cells that is controlled by costimulatory signals. Thus, elimination of Treg's results in diabetes even in the absence of costimulation, which suggests a need for alternative strategies for immunotherapeutic approaches.

PMID:
15467837
PMCID:
PMC518661
DOI:
10.1172/JCI20483
[Indexed for MEDLINE]
Free PMC Article

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