Expression of T11-3 on activated HMC-1 cells.

HMC-1 cells were incubated with mAb 39C1.5 directed against the T11-1 epitope of CD2 (top), with mAb 6F10.3 directed against the T11-2 epitope (bottom), or with control medium (dotted lines). Cells were incubated with mAb or control medium at 37°C for 6 hours. Cells were then washed and stained with FITC-conjugated T11-3 mAb VIT-13 (bold lines). As visible, incubation of HMC-1 cells with T11-1– or T11-2–specific mAbs was followed by expression of the T11-3 epitope. Interestingly, the amounts of expressed T11-3 were significantly higher in HMC-1 cells incubated with T11-1 mAb compared with stimulation with the T11-2 antibody. The dotted line indicates the background control (without antibodies).