Expression of CD22 and cytotoxicity of immunotoxin BL22 in B-CLL cells.

(A) B-CLL cells were cultured for 48 hours with DSP30 or without ODN. They were then stained with a fluorochrome-labeled monoclonal antibody to CD22 or with a labeled isotype control antibody. Cellular fluorescence was assessed by flow cytometry. (B) B-CLL cells were incubated with DSP30 and indicated concentrations of immunotoxin BL22. After 5 days in culture, cell viability was assessed with an MTS assay as described in the text. Results represent means plus or minus SEM from triplicates. Shown is a representative experiment; 2 additional experiments gave similar results. ♦ indicates LMB-2; ■, LMB-9.