Relative expression of different Ikaros isoforms in childhood acute leukemia.

Ikaros is a zinc-finger transcriptional factor playing an essential role in lymphoid lineage commitment and differentiation. Animal models and analysis of human Ikaros in leukemic cells demonstrate deregulation of Ikaros expression. Short isoforms with a truncated DNA-binding domain suppress functions of Ikaros in a dominant-negative manner. Previous studies demonstrated that human leukemias are heterogeneous for Ikaros expression. We estimate the relative level of Ikaros mRNA transcripts in 80 childhood ALL cases in comparison with AML and healthy donor groups. We detected eight major isoforms and several minor mutant isoforms in most patients with acute lymphoblastic and myeloid leukemia and in healthy donors, but the relative level of expression varied. The relatively high level of Ik4A isoform, rarely mentioned in previous reports, was detected in all analyzed groups. The ratio between functional and all isoforms was used to determine functional activity of Ikaros. The ratio was significantly less in AML (p=0.027) and BCR-ABL positive ALL (p=0.0028) than in healthy bone marrow. We found a negative association between the Ikaros ratio and myeloid coexpression in B-cell ALL, the most prominent was for CD15. The Ikaros ratio positively correlates with CD5 and negatively with CD7 expression in T-ALL. We suggest that an anti-proliferation and anti-activation effect of full-length Ikaros may be mediated through regulation of CD5 and CD7.

The incidence of T-cell receptor gene rearrangements in childhood B-lineage acute lymphoblastic leukemia is related to immunophenotype and fusion oncogene expression.

Immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangement is conventionally used for assessment of lymphoid malignant cells. TCR genes rearrangements were reported to occur at high frequency in B-lineage acute lymphoblastic leukemia (ALL). Therefore, we have analyzed 83 children with acute B-lineage ALL (67 de novo patients and 19 relapses) by PCR analysis for clonal IgH, incomplete TCRD (Vdelta2-Ddelta3 and Ddelta2-Ddelta3) and TCRG rearrangements. It was shown that clonal cross-lineage TCR rearrangements were associated with more immature immunophenotype (CD34+, CD117+, CyIgM-) of leukemic cells from patients' bone marrow (BM) samples as compared to cell samples without cross-lineage TCR rearrangements. That was equally detected both in de novo and relapsed cases of disease. Low frequency of clonal TCRG rearrangements was associated with expression of E2A/PBX chimeric oncogene. We suggest that TCRG and TCRD clonal rearrangements in leukemic B-cells are associated with early stages of their differentiation.

Aberrant expression of tumor suppressor genes and their association with chimeric oncogenes in pediatric acute lymphoblastic leukemia.

Aberrant expression of tumor suppressor genes WT 1, RB 1, p53, homozygous deletion of p16 gene and their relationship with expression of oncogenes BCR-ABL, TEL-AML 1, MLL-AF 4, E2A-PBX 1, SIL-TAL 1 were determined in bone marrow samples of children with de novo B-lineage (n=170) and T-lineage (n=25) acute lymphoblastic leukemia (ALL). In contrast to expression of chimeric oncogenes alterations in p16, WT 1, RB 1 and p53 expression were T/B-lineage-unrestricted. Significant association between expression of MLL-AF 4 and WT 1, E2A-PBX 1 and p53; SIL-TAL 1 and homozygous deletion of p16 has been demonstrated.

Late-onset combined immune deficiency associated to skin granuloma due to heterozygous compound mutations in RAG1 gene in a 14 years old male.

We report a male with atypical severe combined immunodeficiency caused by heterozygous compound mutations c.256-257del and c.C1331T in RAG1 gene. The patient presents with recurrent bronchopneumonias with obstruction, chronic fibrosing alveolitis, complicated by respiratory failure, pulmonary hypertension and hepatosplenomegaly. He was diagnosed with agammaglobulinemia at the age of 9. His condition was complicated by granulomatous skin disease at the age of 12 despite regular IVIg substitution. Immunological presentation included profound hypogammaglobulinemia and absence of B cells. Under immunoglobulin substitution for 5 years patient has permanent lymphopenia, skewed phenotype of T cells and diminished number of recent thymic emigrants.

Genetic and demographic features of X-linked agammaglobulinemia in Eastern and Central Europe: a cohort study.

Primary immunodeficiency disorders are a recognized public health problem worldwide. The prototype of these conditions is X-linked agammaglobulinemia (XLA) or Bruton's disease. XLA is caused by mutations in Bruton's tyrosine kinase gene (BTK), preventing B cell development and resulting in the almost total absence of serum immunoglobulins. The genetic profile and prevalence of XLA have not previously been studied in Eastern and Central European (ECE) countries. We studied the genetic and demographic features of XLA in Belarus, Croatia Hungary, Poland, Republic of Macedonia, Romania, Russia, Serbia, Slovenia, and Ukraine. We collected clinical, immunological, and genetic information for 122 patients from 109 families. The BTK gene was sequenced from the genomic DNA of patients with a high susceptibility to infection, almost no CD19(+) peripheral blood B cells, and low or undetectable levels of serum immunoglobulins M, G, and A, compatible with a clinical and immunological diagnosis of XLA. BTK sequence analysis revealed 98 different mutations, 46 of which are reported for the first time here. The mutations included single nucleotide changes in the coding exons (35 missense and 17 nonsense), 23 splicing defects, 13 small deletions, 7 large deletions, and 3 insertions. The mutations were scattered throughout the BTK gene and most frequently concerned the SH1 domain; no missense mutation was detected in the SH3 domain. The prevalence of XLA in ECE countries (total population 145,530,870) was found to be 1 per 1,399,000 individuals. This report provides the first comprehensive overview of the molecular genetic and demographic features of XLA in Eastern and Central Europe.

Significance of serum immunoglobulin G for leukocytosis and prognosis in childhood B-lineage acute lymphoblastic leukemia.

BACKGROUND: This study was conducted to evaluate the significance of serum level of immunoglobulins (Igs) and particularly IgG for leukemic cell persistence in peripheral blood (PB) and prognosis for childhood acute lymphoblastic leukemia (ALL). PROCEDURE: Human sera were obtained from 68 children with primary B-lineage ALL at diagnosis and 46 healthy children (control). Serum level of IgM, IgG, IgA, IgG1, IgG2, IgG3, IgG4, antitumor antibody, homogeneous IgG were quantified by turbidimetric or enzyme-linked immunosorbent assays. RESULTS: The mean values of serum IgM, IgG, IgA at diagnosis were not differed significantly in ALL patients and control children. The level of IgM and IgG1 inversely correlated with white blood cell (WBC) count in PB of patients. Normal range of serum IgG, separated by 25th and 75th percentiles of IgG variables, was associated in patients with decreased WBC count in PB but not in bone marrow (BM) versus patients with low concentration of IgG. Normal range of IgG also favors low frequency of homogeneous IgG and antitumor antibodies. Patients with high level of IgG, besides increased frequency of homogeneous IgG and antitumor antibodies, had worse 3-year overall survival (OS) rate as compared to patients with normal level of IgG (58.8 vs. 91.2%, P = 0.014). CONCLUSIONS: The normal level of serum IgG at diagnosis is a beneficial prognostic factor associated with lower rate of leukemic cell persistence in PB and better outcome of childhood B-lineage ALL.