Freshly purified monocytes (mono), myeloid dendritic cells (mDC) and plasmacytoid dendritic cells (pDC) and in vitro cultured immature (IL-4, GM.CSF; iDC) and maturing monocyte-derived dendritic cells (IL-4, GM.CSF, LPS; matDC) from healthy control heterozygous carriers of Hap 4 (n = 3, each in triplicate; except for pDCs, each in duplicate) were incubated +/− IFNβ (1000 IU/ml; with the exception of pDCs at 2000 IU/ml) for 24 h. IL7Rα was measured by RTPCR relative to GAPDH; mean +/− SEM is shown; *significantly different from media condition by paired t test (iDC, p = 0.006; mDC, p = 0.005); bars represent significant differences between subsets under the same condition by Student's t test (p<0.05).