aAPC-expanded CB-NK cells form immunological synapses with and are cytotoxic against myeloma targets.

<p>A. CMAC-labeled tumor targets (blue) were incubated at a 1∶1 ratio with aAPC-expanded CB-NK cells for 15 minutes. Conjugates were then fixed, permeabilized and stained for NK effector cell F-actin with rhodamine-phalloidin (red). Confocal and brightfield images were acquired; representative images from each slide are shown. aAPC-expanded CB-NK cells form immune synapses with the classic NK target K562 as well as a variety of MM cell lines. B. aAPC-expanded CB-NK cells were co-incubated in triplicate for 4 hours with ⁵¹Cr-labeled target cells at ratios as shown. Supernatants were then harvested and analyzed the next day for ⁵¹Cr content. % Cytotoxicity = (sample value-spontaneous lysis)/(max-lysis-spontaneous lysis) x 100%. CB-NK cells demonstrate dose-dependent cytotoxicity against K562 (classic NK cell target) and MM cells lines RPMI 8266, ARP-1 and U266 (representative of n>3 assays for each cell line). C. aAPC-Expanded CB-NK cells displayed equal or more cytotoxicity against K562 cells versus CB-NK cells expanded with IL-2 alone (representative from n = 4 assays).