Functional ex vivo analysis of NK-cell lysis ability before and after IL-15 injections. (A) PBMCs from participants with ATL and PTCL before and after IL-15 treatment with equal number of NK cells mixed with CD20-coated Raji target cells and uncoated Raji control cells and incubated for 22 hours. We determined the percentages of lysis based on the ratios of surviving coated vs uncoated Raji cells. (B) PBMC samples from patients with detectable circulating ATL cells were stained for the activation marker CD69 on NK cells. Although percentages of activated NK cells were reduced by IL-15 treatments, their percentages were increased after alemtuzumab infusions. ∗∗P < .001; ∗∗∗P < .0001; NS, not significant.