Sensitivity of control and Niemann-Pick disease cells to rituximab. EBV-transformed lymphoid cells from NPD patients (including the patient herein described, a patient with NPD type A and 3 patients with NPD type B) and from 6 control subjects (including a cell line from one of the NPD type B patients that had been corrected by retroviral transfer of the SMPD1 cDNA; denoted with an asterisk) were incubated for 72 hours with rituximab (10 μg/mL). Cell viability was assessed by the MTT test and is expressed as a function of cell-surface expression of CD20, as determined by flow cytometry. Data are means ± SEM of at least 3 independent determinations. Similar results were obtained in the presence of non-decomplemented serum (not shown). In addition, analysis of cell cycle by flow cytometry revealed a slight increase in the sub-G1 population both in control and NPD cells treated with rituximab (not shown).
