Fluorescence microscopy showing epratuzumab-induced trogocytosis. Purified monocytes labeled with PKH26-Red fluorescence were mixed 1:1 with Daudi cells labeled with PKH67-Green fluorescence and treated with labetuzumab (A-B) or epratuzumab (C-I) at 10 µg/mL. Fluorescent images were captured with an Olympus BX66 microscope (Shinjuko, Tokyo, Japan) equipped with a Mercury-100W laser (Chiu Technical Corp., Kings Park, NY), using an Olympus ×40/0.75 air objective lens and a Kodak DC290 Camera (Rochester, NY) set at ×115 zoom. A WB filter was used to allow simultaneous fluorescence of both red and green fluorochromes. Images were captured and processed using Adobe Photoshop CS3 v10 software with a Kodak Microscopy Documentation System 290 plug-in application. Incubation times are indicated on each panel. Bars represent 5 µm. Images were obtained from 1 of 3 repeat experiments, which gave reproducible results.