Addition of immunoglobulins to FCS-based cultures results in a similar CD1 profile of dendritic cells as observed after culture in adult serum. The expression of CD1a and CD1d was analyzed on DCs after 6 days of culture in IL-4 and GM-CSF and AS, FCS, or FCS with a high dose of IVIg (20 mg/mL). The IVIg was dissolved in 0.2 M glycine, which was included as control. The graphs show the average MFI of CD1a and CD1d cell surface expression (± standard deviation) from 6 individual donors (A). The expression of CD1 molecules on DCs cultured for 6 days in the presence of IL-4, GM-CSF, and FCS with increasing doses of IVIg (0.004 to 10 mg/mL IVIg) was measured by flow cytometry (B). Three representative donors of 6 are plotted as individual lines (■, ○, and ◆). As references, vertical lines depict the average levels of IgG added to the AS DC cultures (∣) and found in serum of healthy individuals (¦). Furthermore, the effect of adding Fc fragments instead of intact immunoglobulins, or equimolar amounts of bovine serum albumin (BSA) instead of IVIg, to the FCS cultures was assessed by determining the expression levels of CD1a and CD1d on DCs after 6 days of culture. The graphs show the average MFI of CD1a and CD1d cell surface expression (± standard deviation) from 4 individual donors (C). Statistical differences were assessed by paired t test and considered significant when *P < .05; **P < .01 and ***P < .001.