Response of primary ALL blasts to CpG stimulation. Bone marrow biopsies from precursor B-ALL patients were cultured in the presence or absence of CpG ODN 2006 or 1760 for 72 hours and then analyzed for expression of CD40 (10 patients), CD80 (6 patients), and CD86 (6 patients). Specific gating on leukemic blasts was achieved by CD10 and CD19 costaining. The cumulative results expressed as the mean change (± SE) in the percentage of positive cells following CpG ODN treatment.