NK cells from PBMCs of the patient in remission and the healthy twin have comparable cytolytic activity. (A) MACS sorted NKs isolated from PBMCs of the patient drawn at diagnosis (left bar), in remission (central bar) and from the healthy twin (right bar) were used in RDL assays against calcein labeled BMMCs from the patient at diagnosis as targets (red). 4 h RDL reactions were run at an E : T ratio of 2.5 : 1 and incubated with a 10 nM dose of SPM-2 versus NKs alone as control. Error bars: arithmetic means over 3 separate experiments (n = 3). (B) The same NK effector populations as in panel A were also used in 3 h ADCC reactions at the same E : T ratios. Target cells were calcein labeled Raji cells (CD20pos). Reactions mediated by 10 μg/ml (approx. 70 nM) of the commercial CD20-antibody RituximabTM (blue). Error bars: arithmetic means over 3 separate experiments (n = 3).