FIG. 5.

ADA binds to cell surface DPP4 in human DC/macrophages. Human PBMCs were cultured on six-well plates for 4 h and were incubated with ADA (50 ng/mL) for 30 min, following which the cells were washed and stained with anti-ADA and DPP4 Abs. A: Representative confocal micrograph showing expression of DPP4, ADA, and their colocalization. B: The binding of ADA to DPP4 was investigated in cultured PBMCs by competition assays in which in exogenous ADA was added, followed by the competitive inhibition of ADA binding by exogenously added soluble DPP4 and assessment of ADA content on cell surface. The flow cytometric contour plots depict inhibition of ADA binding to cells by exogenously added soluble DPP4 (sDPP4). C: Representative mean fluorescent intensity of ADA on DPP4⁺ cells are shown. *P < 0.05 when compared with control; #P < 0.05 when compared with ADA-treated cells. (A high-quality digital representation of this figure is available in the online issue.)