Different E-rosetting properties of human peripheral blood NK- and K-cells

Mononuclear, non-adherent blood leukocytes were separated into the spontaneously E-rosetting (E+) and non-E-rosetting (E-) fraction. NK- and K-cell activity was determined simultaneously in a 4 h assay against 51Cr-labeled K 562 cell line cells and rabbit antiserum coated mouse leukemia cells (Gr/E) respectively. In each case E- exhibited a significantly higher K-cell activity than E+ [M16 donors E-:E+ = 46 +/- 11:10 +/- 6 (% specific cytotoxicity)]. With regard to NK-cell activity E- of only 7 donors was significantly more active than E+ [M7 donors E-:E+ = 49 +/- 15:20 +/- 10]. Six times the activities of the two fractions were not significantly different [M6 donors E-:E+ = 46 +/- 15:39 +/- 14]. On the other hand E+ of 3 donors displayed a significantly stronger activity than E-[M3 donors E-:E+ = 13 +/- 10:36 +/- 9]. These results confirm the heterogeneity of NK-cells with respect to E-rosetting properties and indicate that NK- and K-cells of at least 3 donors may belong to different cellular subsets [NK:E- less than E+; K:E- greater than E+].