Immunophenotypic Profile of Blast Cells as a Marker for Diagnosis of Relapsed Children Acute Lymphoblastic Leukemia

Abstract

Immunophenotyping of leukemia cells was studied in this work; minimal residual disease was monitored among children with acute lymphoblastic leukemia under conditions of relapse and complete remission after the application of ALLIC-BFM 2009 cytostatic therapy. The study showed that after application of ALLIC-BFM 2009 therapy, 88% of children had complete remission, and 12% had relapses. Among patients with relapses, the number of blast cells in the bone marrow was at a high level (more than 6%). Monitoring of patients during therapy established an increase in the minimal residual disease level of more than 1% after treatment in patients with recurrent disease. Immunophenotyping of blast cells among patients with relapse showed the expression of linear independent antigens HLA (93%), Auti-TdT (91%), CD10 (78%), CD38 (91%) and CD34 (57%) and B-linear antigens: CD19, CD22, CD58, CD79a, the highest expression was found for the CD19 antigen. A low level of expression of CD45 (28%) was recorded with relapses of acute lymphoblastic leukemia and high (89%) level was with complete remission of the disease. We did not detect expression of antigens characteristic of T-cell acute lymphoblastic leukemia in bone marrow of patients with acute lymphoblastic leukemia, both with relapses and with remission. At the same time, the expression of myeloid antigens (CD33 and CD13) was noted among acute lymphoblastic leukemia patients. Among patients, the incidence of acute lymphoblastic leukemia was the most pronounced in children aged from 3 to 6 years – 37 patients (35.2%) and aged from 6 to 9 years – 26 (24.8%) patients. The highest accidence was found among patients with chromosomal translocation TEL / AML – 22 (21%) patients with a median age 5 years. In second place, the frequency of mutations is the translocation of E2A / PBX1. BCR / ABL translocation was less common. It was noted in 1.9% of patients, but the expression of this gene indicated a bad course of the disease, as patients after cytostatic therapy under the ALLIC BFM 2009 program had a recurrence. Recurrence was also observed in patients with TEL/AML chromosomal translocation. Determination of minimal residual disease showed its increased level in patients with chromosomal aberrations BCR / ABL and TEL/AML throughout the treatment phase. In addition, patients in these groups were diagnosed with initial leukocytosis followed by leukopenia after a course of chemotherapy. Patients of all groups showed a decrease in hemoglobin. The biggest changes in clinical and laboratory parameters were found between patients with chromosomal translocations BCR/ABL and TEL/AML, as evidenced by the development of relapses in patients of these groups. The low level of association between karyotype disorders, with the formation of AF4/MLL and E2A/PBX1, and clinical and laboratory parameters in patients with acute lymphoblastic leukemia may indicate that the isolated clonal disorders are independent prognostic factors for the course of the disease