Analysis of modulation and coating of the CD48 antigen induced by the ex vivo incubation of splenocytes or BM cells with CD48 MoAb. Single-cell suspensions of spleen (top panels) and BM (bottom panels) from non-BMT B6 control mice were incubated with CD48 MoAb (CD48aby) (20 μg/mL) for 30 minutes on ice. Cells were washed and then incubated with goat anti-hamster FITC (anti-H) or CD48-FITC (CD48). The thin lines are the isotype-specific negative control MoAb staining and the dark lines are the staining with either CD48-FITC or anti-hamster FITC. The proportion of CD48^hiBM cells and splenocytes was markedly reduced after CD48 MoAb. Only a low proportion of BM or spleen cells exposed to CD48 MoAb bound goat anti-hamster IgG FITC.