Repetitive testing and storage of human effector cells in natural killing and antibody-dependent cell-mediated...

Daily variation in natural killer (NK) and antibody-dependent cell-mediated cytotoxicity (ADCC) assays is problematic. When fresh peripheral blood mononuclear cells (PBM) from 4 donors were tested repeatedly, the ADCC and NK values tended to fall in the same rank order on each day tested, suggesting that repetitive assay of control donors could serve as an index for daily variation. Cryopreservation of PBM resulted in decreased and quite variable recovery of ADCC and NK. Cryopreservation, therefore, would not be an adequate control for daily variation. Storage of PBM at 4 degrees C for 24 h resulted in better recovery of ADCC and NK activities than did cryopreservation.