D6 expression is upregulated by IL-6 and IFN-γ. (A) IL-6, in concert with its soluble receptor (IL6/sIL6-R at a 1:5 molar ratio) induces significant and prolonged upregulation of D6 expression in LECs (*P < .05). (B) IL-6/sIL-6R dose dependently enhances D6 expression in LECs as assessed by QPCR. (C) IFN-γ rapidly enhances D6 expression in lymphatic endothelial cells as assessed by QPCR. (D) D6 protein expression is upregulated by 24 hours following IL-6 stimulation of LECs as demonstrated by immunostaining of IL-6 treated LEC monolayers (scale bar, 100 μm). (E-F) Quantitation of the number of D6-positive cells per field of view for IL-6– and IFN-γ–treated LECs. Note that each point represents the average of 5 field-of-view counts. GAPDH, glyceraldehyde-3-phosphate dehydrogenase; PBS, phosphate-buffered saline.