Crucial contribution of thymic Sirpα+ conventional dendritic cells to central tolerance against blood-borne antigens in a CCR2-dependent manner

T Baba, Y Nakamoto, N Mukaida - The Journal of Immunology, 2009 - journals.aai.org
T Baba, Y Nakamoto, N Mukaida
The Journal of Immunology, 2009journals.aai.org
Thymic dendritic cells (DCs) as well as thymic epithelial cells are presumed to be major
sentinels in central tolerance by inducing the apoptosis of autoreactive T progenitor cells.
The thymic DC population is composed of heterogeneous subsets including CD11c+ B220+
plasmacytoid DCs, CD11c+ B220− CD8α+ signal regulatory protein α (Sirpα)− and CD11c+
B220− CD8α− Sirpα+ conventional DCs (cDCs). However, the distinctive role of each DC
subset remains undefined. We show herein that Sirpα+ cDCs, a minor subpopulation, was …
Abstract
Thymic dendritic cells (DCs) as well as thymic epithelial cells are presumed to be major sentinels in central tolerance by inducing the apoptosis of autoreactive T progenitor cells. The thymic DC population is composed of heterogeneous subsets including CD11c+ B220+ plasmacytoid DCs, CD11c+ B220− CD8α+ signal regulatory protein α (Sirpα)− and CD11c+ B220− CD8α− Sirpα+ conventional DCs (cDCs). However, the distinctive role of each DC subset remains undefined. We show herein that Sirpα+ cDCs, a minor subpopulation, was disseminated in the thymic cortical area with some of them uniquely localized inside perivascular regions and nearby small vessels in the thymus. The Sirpα+ but not Sirpα− cDC subset can selectively capture blood-circulating Ags. Moreover, in CCR2-deficient mice, the thymic Sirpα+ cDC subset, but not other thymic cell components, was moderately decreased especially in the perivascular regions. Concomitantly, these mice exhibited a modest impairment in intrathymic negative selection against blood-borne Ags, with the reduced capacity to uptake blood-borne Ags. Given their intrathymic cortical localization, CD11c+ B220− CD8α− Sirpα+ cDCs can have a unique role in the development of central tolerance against circulating peripheral Ags, at least partially in a CCR2-dependent manner.
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