CD11b^hiIa^lo DCs exhibit a limited or no capacity of stimulating CD4 T-cell proliferation in allo-MLR and auto-MLR. (A) CD4⁺ T cells (H-2^d) were cultured with imDCs (H-2^b), mDCs (H-2^b), CD11b^hiIa^lo DCs (H-2^b), or LPS-treated CD11b^hiIa^lo DCs (H-2^b) at various APC/T cell ratios, and the relative cell number of viable CD4⁺ T cells in each well was measured on day 5 by FACS. (B-D) CD11b^hiIa^lo DCs, LPS-treated CD11b^hiIa^lo DCs, imDCs, or mDCs were cocultured with OVA_323-339 peptide–specific congenetic CD4 T cells in the presence of OVA_323-339 peptides. After 5 days, the relative number of viable CD4⁺ T cells in each well (B) and the activation-related markers CD25 and CD69 expression on CD4 T cells (C) were detected by FACS, and the levels of IFN-γ in the supernatant (D) were assayed by ELISA. Data in panels A, B, and D represent mean ± SD. Plots in panel C are labeled with the percentage of double-positive cells.