Investigation of NK activation during IPH2101 treatment. (A) Activation of NK as measured by CD69 expression after IPH2101 treatment. The expression of the cell-surface activation marker CD69 was performed on NK and T cells before and 24 hours after IPH2101 infusion. The 2 representative patients included received either 0.003 or 3 mg/kg doses. (B) Increased expression of CD69 on NK cells and serum levels of TNF-α and MIP-1β in patients who received IPH2101 infusions of 0.3, 1, and 3 mg/kg compared with patients receiving doses < 0.3 mg/kg. The activation marker CD69 was analyzed by flow cytometry on NK cells before and 24 hours after IPH2101 infusion. Serum levels of TNF-α and MIP-1 β were determined by ELISA before and 24 hours after IPH2101 infusion.