Different binding patterns of LAG-3 and class II-specific mAb on human immature DC. (A,C) Immature DCs were incubated on poly-l-lysine–coated surfaces saturated with PBS–dry milk 3% at 37°C. After 15 minutes of temperature equilibration at 4°C, cells were labeled with LAG-3Ig in green and a class II-specific mAb in red (I3 in panel A, CDw78 in panel C). Bound LAG-3Ig and I3 or CDw78 were revealed using Alexa 488– and Alexa 594–conjugated secondary antibodies, respectively. (B) Cells were pretreated with 10 mM MCD prior to adherence and labeling. Scale bars, 5 μm. DIC indicates differential interferential contrast. The pictures are representative of the results obtained in at least 3 different experiments.