Minimal residual disease(MRD)in childhood B-lineage acute lymphoblastic leukemia(B-ALL)is an important indicator for treatment and prognosis. We set up a flow cytometric method with three panels of 4-color antibodies to enhance detection sensitivity and test its clinical application.

Three panels of 4-color fluorochrome monoclonal antibodies(CD₄₅/CD₁₉/CD₁₀/ CD₃₄, CD₄₅/CD₁₉/CD₁₀/CD₁₃ and CD₄₅/CD₁₉/CD₂₂/CD₃₄)were used to detect the leukemia-associated aberrant immunophenotyping(LAIP)cells in 18 bone morrow samples of newly diagnosed B-ALL patients(the group A)and 67 bone morrow samples of clinical remission patients(the group B). All the cases were inpatients or scheduled follow-up patients registered in the Department of Pediatrics, Sichuan Provincial People's Hospital from June 2004 to December 2007. Meanwhile, B cells of 12 normal bone marrows were used as controls(the group C).

Eight panels of the 2-parameter dot plots to monitor the minimal residual disease in the clinical remission patients were set up to tell leukemia-associated aberrant immunophenotype cell populations of B-lineage acute lymphoblastic leukemia from the normal. The positive detection rate for minimal residual disease was 89%(16/18)in the group A and 48%(32/67)in the group B(P<0. 01). The average leukemia-associated aberrant immunophenotype cell levels of the group A(67.8±36.4)%(±s)were obviously higher than those of the group B(0.056±0.083)%(±s)with statistical significance(P<0.01). By analyzing the leukemia-associated aberrant immunophenotype cell results of 3 relapsed patients with regular follow-up, all of them were found minimal residual disease positive at remission stage, and their leukemia-associated aberrant immunophenotype cell level rose sharply immediate before recurrence.

The method described here was a sensitive and rapid method for monitoring minimal residual disease in children with B-lineage acute lymphoblastic leukemia, and it was easy to be standardized for clinical application.