CD19-specific CTL clone lyses CD19⁺ primary B-ALL.

CD19-specific effector cells from a CD8⁺ CTL clone and a neuroblastoma-specific CD8⁺ CTL clone (insert) were incubated with ⁵¹Cr-labeled CD19⁺CD10⁺ primary B-ALL blasts (⋄), JM1 CD19⁺ B-ALL line (▵) and CD19⁻Be2 neuroblastoma line (×). Lytic activity was calculated by measuring chromium release after 4 hours. Spontaneous release for each target was 15% or less. Average counts ± SD from triplicates are shown. The percentage, as measured by flow cytometry, of CD19⁺CD10⁺ blasts was 84% and of CD19⁺CD10⁻ B cells was 4%, in the primary sample.