IL-21R expression, STAT phosphorylation, and growth inhibition in human B lymphoma lines treated with rIL-21.

1Mean fluorescence intensity (MFI) minus background staining with isotype-matched control antibody.2Ratio of MFI for P-STAT staining in stimulated versus control cells after 15 minute treatment with 10 ng/mL rIL-21. Mean and SD are from 2 experiments. Following rIL-21 stimulation, STAT5 phosphorylation was detected in only two cell lines, MC-116 and IM-9.3Percentage growth inhibition was determined by live cell counts after 7 days culture with 50 ng/mL rIL-21 or control media (representative data from one of two experiments). Similar results were observed with 3H incorporation.