Sequential monitoring of p15 methylation status in peripheral blood from patients with acute leukemia.

(A, B) Results on ethidium bromide-stained agarose gels and Southern blots for patients with L1, L2, M6, M3, and M7 subtypes at diagnosis (lanes 1, 4, 7, 10, and 12) or morphologic remission. The adult with the M6 subtype in whom active leukemia developed had methylatedp15 sequences (panel B, lane 9). The child with the M7 subtype had persistent unmethylated p15 status largely associated with morphologic remission and lack of residual leukemia for 3 months (lanes 13-15). (C, D) Results on agarose gels and Southern blots for patients with M2, ABL, and M4 subtypes at morphologic relapse, during active leukemia or residual leukemia, or in remission. HS-Sultan DNA (HS) served as a methylated control. The 1-kb ladder is the molecular-weight standard. The adult with M2 subtype had p15 methylation at diagnosis and relapse (lanes 1-2). The adult with ABL had p15methylation in association with morphologic relapse (lane 7) and the subsequent stage of active leukemia. p15 methylation was detected at morphologic remission in the adult with M4 subtype, who had relapse 2 weeks later (lanes 9-10).