Authors:
Burles A. Johnson III, David J. Kahler, Babak Baban, Phillip R. Chandler, Baolin Kang, Michiko Shimoda, Pandelakis A. Koni, Jeanene Pihkala, Bojan Vilagos, Meinrad Busslinger, David H. Munn, and Andrew L. Mellor
Summary:
A discrete population of splenocytes with attributes of dendritic cells (DCs) and coexpressing the B-cell marker CD19 is uniquely competent to express the T-cell regulatory enzyme indoleamine 2,3-dioxygenase (IDO) in mice treated with TLR9 ligands (CpGs). Here we show that IDO-competent cells express the B-lineage commitment factor Pax5 and surface immunoglobulins. CD19 ablation abrogated IDO-dependent T-cell suppression by DCs, even though cells with phenotypic attributes matching IDO-competent cells developed normally and expressed IDO in response to interferon γ. Consequently, DCs and regulatory T cells (Tregs) did not acquire T-cell regulatory functions after TLR9 ligation, providing an alternative perspective on the known T-cell regulatory defects of CD19-deficient mice. DCs from B-cell–deficient mice expressed IDO and mediated T-cell suppression after TLR9 ligation, indicating that B-cell attributes were not essential for B-lymphoid IDO-competent cells to regulate T cells. Thus, IDO-competent cells constitute a distinctive B-lymphoid cell type with quintessential T-cell regulatory attributes and phenotypic features of both B cells and DCs.
Source:
Proceedings of the National Academy of Sciences of the United States of America; Vol. 107, No. 23, 10644-10648 (06/08/10)