Capacity of OCs to stimulate alloreactive T cells. (A) Allogeneic peripheral blood mononuclear cells (PBMCs; 2 × 10⁵) were cocultured with 10⁴ LPS-matured DCs (mDCs), OCs, macrophages (Mφ), or PBMCs from the same donors (n = 3), and T-cell proliferation was determined on day 4 with ³H-thymidine assay. (B) OC capacity to activate both CD4⁺ and CD8⁺ alloreactive T cells in mixed lymphocyte reaction (MLR) assay. Allogeneic PBMCs or purified CD4⁺ or CD8⁺ T cells (2 × 10⁵) were cocultured with 10⁴ OCs, and T-cell proliferation was determined on day 5. Summarized data (mean ± SEM) of cell proliferation (cpm) of cells from 3 different donors are shown. (C) OC capacity to activate both CD4⁺ and CD8⁺ alloreactive T cells measured by CFSE dilution assay. CFSE-labeled CD3⁺ T cells were cocultured with allogeneic OCs and DCs for 5 days. Representative results from 1 of 3 performed experiments are shown. (D) Major histocompatibility complex (MHC) restriction in MLR assay. Antibodies for HLA-ABC or HLA-DR (10 μg/mL) were added to the culture of MLR assay. Isotype IgG was used as control. Shown are percentages of inhibition (mean ± SD) from 3 independent experiments using cells from 3 different blood donors.