Expression analysis of surface molecules on human thymic dendritic cells with the 10th HLDA Workshop antibody panel

Dendritic cells (DC) in the thymus have an important role in the establishment of central tolerance by promoting negative selection of autoreactive T cells and regulatory T-cell differentiation. Whereas human DC have recently been studied in various tissues in more detail, thymic DC subsets are still ill-defined. In the present work, we studied the binding of 71 monoclonal antibodies (mAb) submitted to the HLDA10 workshop to human CD123(+) plasmacytoid DC and the two subsets of conventional DC (cDC, CD141(+) and CD11b(+)) isolated from thymus tissue of infants undergoing corrective heart surgery. Within the panel, we found mAb binding to thymic pDC and both cDC subsets (for example, anti-Clec12A, TIM-3, Clec4A, CCR5, Axl, FLT3), but most of them additionally reacted with other thymic cell types. MAb directed to CD85h (ILT1) and the C-type lectin Clec7A (now CD369) reacted selectively with both cDC subsets, but not with other cells. Only one mAb directed to CD85g (ILT7) stained thymic pDC in a highly specific manner. Clec9A (DNGR1, now CD370) was the only tested HLDA10 antigen exclusively expressed on thymic CD141(+) cDC. The present report summarizes all data obtained.