The CD1 profile of monocyte-derived dendritic cells is influenced by the type of serum they are cultured in. The expression of CD1a and CD1d was determined on blood myeloid DCs (MDCs) and Langerhans cells (LCs) in the epidermis of skin. MDCs were identified in PBMCs by gating on size, followed by a gate on cells negative for lineage markers (CD3, CD8, CD14, CD16, CD19, and CD56). CD11c⁺ HLA-DR⁺ MDCs were subsequently identified among the lineage-negative cells, and the CD1a and CD1d profile of MDCs was displayed. To assess the CD1 profile of LCs, cells were allowed to migrate out from epidermis sheets of skin biopsies for 2 to 3 days. The cells were subsequently analyzed by flow cytometry, and LCs were identified by size and high expression of HLA-DR and their expression of CD1a and CD1d was determined. The histograms show 1 representative donor of 10 for MDCs (black) and 1 of 4 for LCs (dotted) (A). The expression of CD1 molecules was determined on monocyte-derived DCs cultured in human adult serum (AS) or fetal calf serum (FCS) and IL-4 and GM-CSF for 6 days to allow differentiation of DCs from monocytes. The mean fluorescence intensity (MFI) of CD1a, CD1b, CD1c, and CD1d on DCs cultured in AS () or FCS () from 18 donors was measured (B). Average CD1 expression is depicted by a line in the graphs. The statistical difference between the CD1 expression on DCs grown in AS and FCS was determined by paired t test. DCs cultured in AS and FCS obtained a similar overall phenotype with respect to expression of MHC class II (HLA-DR), MHC class I (HLA-A2), and DC-SIGN, as well as their lack of CD14 expression as determined by flow cytometry (C). The numbers on the plots are the percentages of dendritic cells that fall within each rectangle. The graphs show data from 1 representative donor of 6. Immature DCs grown in either AS or FCS were irradiated (30 Gy) and cocultured with allogeneic CD3⁺ T cells at a ratio 1:10 for 2, 4, and 6 days, and T-cell proliferation was determined by incorporation of ³H-thymidine (1 μCi [0.037 MBq]/well for 6 hours) and presented as counts per minute (cpm) (D). The graph shows the average proliferation plus or minus standard deviation of triplicates from 1 of 2 donors. To assess the ability of the DCs to mature, both DCs cultured in AS and FCS were exposed to 100 ng/mL LPS for 16 hours and the expression of CD83 was determined by flow cytometry (E). Histograms show unstained DCs (filled), unstimulated DCs (dashed), and LPS-stimulated DCs (solid) on DCs grown in either AS or FCS. One representative experiment of 6 is shown.