Within DC clusters, we found distinct aging manifestations in the cDC2 subsets by comparing DC clusters in the t-SNE map (Fig. 3J). Cells from the YA group grouped together in clusters 0 and 1 (named cDC2-A), whereas cells in AA group grouped distinctively in clusters 3, 4, 10 and 11 (named cDC2-B). The expression signature of cDC2-A cells included antigen presentation-related genes such as AHR, CLEC4E, and CLEC12A, whereas the expression signature of cDC2-B cells included inflammatory and aging-associated genes such as IFN-stimulated genes, IL1B, CDKN2D, DDIT4, CXCL8, and DUSP2 (Fig. S7J and S7K). Moreover, the comparative functional analysis of DEGs between the two clusters indicated that cDC2-A had intact immune regulation and antigen presentation function, while aging-related cDC2-B with high HLA-DQA2 expression exhibited increased inflammatory signaling pathways, such as the response to hypoxia and IL-1 signaling (Fig. 3K). We further confirmed that CLEC12A+ cDC2s were decreased in aging by FACS (Fig. 3L and 3M). Taken together, these findings indicate that aging curtails DC antigen presentation ability and upregulates inflammatory and aging-associated gene expression in DCs.