Activating receptor–mediated triggering of NK cell cytolysis is not cyclosporin A sensitive.

(A-B) Killing assay using the murine FcγR⁺ P815 cell line with the NK cell clone 262 ([A] CD158a⁺activating) or the NK cell clone 10 ([B] CD94⁺activating) at the effector-target ratio (E/T) of 2:1 in the presence of anti-CD158a mAb (A) or anti-CD94 mAb (B) with 3 μg/mL CMA or 500 ng/mL CsA. Results obtained with anti-CD16 mAb are shown for comparison. “nil” indicates NK cell cytolysis in the absence of mAb. Cytolytic activity of the NK cell clone 45 against K562 (C) or 721.221 (D) or Jurkat (E) target cells in medium alone (○) or in the presence of either 3 μg/mL CMA (▪) or 500 ng/mL CsA (▴) was evaluated in a 4-hour ⁵¹Cr-release cytotolytic assay at the indicated E/T ratio. Results are expressed as the percentage of specific ⁵¹Cr release and are representative of 3 independent experiments using different NK cell clones.