Fig. 6
Natural killer (NK) cells exposed to rituximab (RTX) can become hypo-responsive in a donor-dependent fashion. Freshly isolated peripheral blood mononuclear cells (PBMCs) from 11 healthy donors were cultured overnight with or without (w/o) RTX in medium without human serum. After washing, PBMCs (effector cells (E)) and 51Cr-labeled K562 (target (T)) cells were co-cultured for 4 hours. Percent specific lysis was determined by measuring 51Cr in the supernatant. For every donor a ratio of the % specific lysis with and without RTX ((RTX)/(w/o RTX)) was calculated for each E/T and statistically analyzed by comparison with a hypothetic mean value of 1 using the one-sample t test. a Although eight donors had no significant changes in NK cell cytotoxicity (b) we observed that RTX significantly inhibited NK cell cytotoxicity in three donors (p < 0.05). c To compare all donors, we calculated the area under the curve (AUC) for each cytotoxicity assay with and without RTX pretreatment. Shown is log10 (AUC with RTX)/(AUC w/o RTX). Data were analyzed using the one-sample t test (not significant, p = 0.0593; bar mean)