Enhanced cytotoxicity of myeloma patients’ PBMC. A chromium release cytotoxicity assay was used to test the activity of patients’ mobilized effector cells against a human myeloma cell line, RPMI8226 at an E:T of 20:1 (n= 5 patients per group) (a) and against a human CML cell line, K562, at an E:T of 20:1 (n= 5 patients per group) (b). (Percent specific lysis of tumor cells were comparable in each IL-2 dose group, therefore, cytotoxicity results were combined. P values represent statistical significance in comparing day 7 and day 11 to day 0 (baseline) specific lysis.