Alicja Chybicka

Immune reconstitution after haematopoietic cell transplantation in children: immunophenotype analysis with regard to factors affecting the speed of recovery.

Summary.  Immune reconstitution was studied prospectively in 66 children who underwent 77 haematopoietic cell transplantations (HCT): 46 autologous HCTs in 39 patients and 31 allogeneic HCTs in 27 patients. We studied the dynamic analysis of immune recovery with regard to potential factors affecting its speed, including age, type of HCT, diagnosis, graft‐versus‐host disease (GvHD) and cytomegalovirus (CMV) infection reactivation. Absolute counts of different lymphocyte subsets and immunoglobulin serum levels were determined in peripheral blood of patients on d −7 and +16, and then at various intervals up to 24 months post transplant. Common patterns of immune recovery after both allogeneic and autologous HCT were identified: (i) CD4+CD45RO+ peripheral T‐cell expansion on d +16; (ii) inverted CD4+:CD8+ ratio from d +30 onwards; (iii) rapid natural killer (NK) cell (CD16±CD56+) count normalization. We observed prolonged T‐cell lymphopenia (CD3+, CD3+CD4+, CD4+CD45RA+) until 24 months after autologous HCT, whereas in the allogeneic setting CD3+CD4+ cells, including naive CD45RA+ cells, returned to normal values at 9 months post transplant. Age > 10 years and coexistence of GvHD and CMV reactivation were associated with a substantial delay in T‐ (CD4+, including CD45RA+) and B‐cell recovery after allogeneic HCT. Multidrug GvHD prophylaxis resulted in impaired T‐ (CD4+, CD4+CD45RA+) and B‐cell reconstitution only in the early phase after allogeneic HCT (up to 4 months). Our results demonstrated that T‐cell recovery was severely impaired in children after autologous HCT. It should be emphasized that specific approaches to enhance immune reconstitution are necessary to control minimal residual disease and avoid the risk of infectious complications in the autologous setting. Thymic involution after allogeneic HCT seems to be associated with age and coexistence of GvHD and CMV reactivation.

A prospective analysis of immune recovery in children following allogeneic transplantation of t-cell-depleted or non-T-cell-depleted hematopoietic cells from HLA-disparate family donors.

Transplantation of HLA-disparate hematopoietic stem cells from related donors is an alternative for the treatment of patients lacking an HLA-matched family or unrelated donor. In the cases of a single HLA antigen disparity, extensive T-cell depletion (TCD) is not required, yet antithymocyte globulin (ATG) must be administered to prevent GvHD or graft rejection. The major concern after HLA-mismatched transplants remains immune reconstitution. Therefore, we prospectively studied the recovery of lymphocyte subsets among 22 children transplanted from partially HLA-matched family donors. We compared two groups of patients: (1) the TCD group included children (n = 1.3) who received grafts after TCD (MACS) due to an HLA disparity for more than one antigen; (2) The non-TCD group included children with either one HLA-mismatched antigen, n = 7; or more than one disparate antigen (n = 2) who received T-cell-repleted grafts and ATG. The study demonstrated rapid NK cell reconstitution among the TCD group. TCD compromised T-cell reconstitution, thus preventing GvHD, but resulting in a higher incidence of severe infectious complications, graft rejection, and disease relapse. Increasing mixed chimerism required the application of donor T-cell addbacks, thus potentiating the risk of GvHD. Primary graft rejection occurred in eight children, who required further transplants. In the non-TCD group faster T-cell reconstitution (predominantly CD3+CD8+ cells) resulted in a lower rate of relapse and infection, yet a higher rate of GvHD, including two fatal cases. Due to improved immune reconstitution, in spite of an increased risk of GvHD, non-TCD transplants from single HLA-mismatched family donors remain a valuable option for children without matched donors.

Management of familial hypercholesterolemia in children and adolescents. Position paper of the Polish Lipid Expert Forum

Familial hypercholesterolemia (FH) affects on average 1 in 500 individuals in European countries, and it is estimated that FH in Poland may affect more than 80,000 people. However, in Poland, only about 20% of the population is estimated to have been diagnosed with FH, of which only a small number receive adequate treatment. FH results in more rapid development of atherosclerosis and is associated with a high risk of cardiovascular events. Atherosclerosis develops beginning in childhood in patients with FH and reaches advanced stages before clinical manifestations develop. Inadequate diagnostics and treatment of FH in Polish children suggests a need for raising the level of awareness and understanding of the condition in both society and among health professionals. These recommendations present the current epidemiological status, guidelines for diagnosing FH in Polish children and adolescents, and effective treatment options.

Megachemotherapy followed by autologous stem cell transplantation in children with Ewing's sarcoma.

Abstract:  Twenty‐one children with high‐risk Ewings tumor received high‐dose chemotherapy with a PBSCT. Aim of the study was evaluation of efficiency and safety of this procedure. All but three patients have meta‐static disease at presentation. There were 11 females and the median age at diagnosis was 12 yr (range 4.5–18 yr). Megachemotherapy consisted of melphalan 140 mg/m2/busulfan 16 mg/kg in 12 patients, melphalan 140 mg2/treosulfan 10.0 g/m2 in two patients and melphalan with other drugs in seven patients. Eight of 11 patients transplanted in CR survived with a median follow‐up 24 month (range 14–60) and probability of 2‐year OS is 0.68 and DFS is 0.63. There was no severe regimen‐related toxicity in this group. Children transplanted without remission died: Two of them due to transplant related causes and eight had progression of disease in a median time 7 month after PBSCT. Megachemotherapy with PBSCT is a safe procedure in children with Ewings sarcoma in remission. Autologos transplantation in children with metastatic Ewings sarcoma seems to improve their outcome. Patients with Ewings sarcoma, resistant to conventional therapy and with recurrent disease did not benefit from megachemotherapy. New approaches such as anti‐tumor vaccination or using of imatinib are reasonable to introduce in patients with relapsed or resistant to therapy Ewings tumor.

Immunologic Effects of Intermediate-Dose IL-2 i.v. After Autologous Hematopoietic Cell Transplantation in Pediatric Solid Tumors

Adoptive immunotherapy with interleukin-2 (IL-2) may control minimal residual disease (MRD) and prevent relapse after autologous hematopoietic cell transplantation (AHCT). The objective of this study was to determine the immunologic effects of intermediate doses of intravenous (i.v.) IL-2 after AHCT in children with poor-prognosis solid tumors. Eleven patients received a median five cycles consisting of escalating doses of IL-2 i.v. for 5 days after a median time interval of 94 days post-AHCT. The phenotype of lymphocyte subsets was investigated before and after each cycle, and parallel determination of natural killer (NK) cell activity was performed. Immunotherapy induced a significant increase in total lymphocyte count (TLC), T, NK, and, to some extent, B cells. Among NK cells, CD56+ bright cells expanded more than CD56+ dim cells. High expansion of CD56+ cells with CD94 inhibitory receptor was observed, whereas no difference was recorded in the number of CD3+ CD56+ and CD8+ CD57+ cells. NK activity stabilized after the first cycle of IL-2 and remained elevated during the study period. Cycles of IL-2 immunotherapy induced repeated significant expansion of T cells and NK cells, mostly of the immature CD56+ bright phenotype. Despite enhanced NK activity, relapses occurred frequently, which might have been due to increased CD94 activation and a poor response from the cytotoxic NK T cells and CD8+ CD57+ T cells.

c.1810C>T Polymorphism of NTRK1 Gene is associated with reduced Survival in Neuroblastoma Patients

BackgroundTrkA (encoded by NTRK1 gene), the high-affinity tyrosine kinase receptor for neurotrophins, is involved in neural crest cell differentiation. Its expression has been reported to be associated with a favourable prognosis in neuroblastoma. Therefore, the entire coding sequence of NTRK1 gene has been analysed in order to identify mutations and/or polymorphisms which may alter TrkA receptor expression.MethodsDNA was extracted from neuroblastomas of 55 Polish and 114 Italian patients and from peripheral blood leukocytes of 158 healthy controls. Denaturing High-Performance Liquid Chromatography (DHPLC) and Single-Strand Conformation Polymorphism (SSCP) analysis were used to screen for sequence variants. Genetic changes were confirmed by direct sequencing and correlated with biological and clinical data.ResultsThree previously reported and nine new single nucleotide polymorphisms were detected. c.1810C>T polymorphism present in 8.7% of cases was found to be an independent marker of disease recurrence (OR = 13.3; p = 0.009) associated with lower survival rates (HR = 4.45 p = 0.041). c.1810C>T polymorphisms unfavourable prognostic value was most significant in patients under 18 months of age with no MYCN amplification (HR = 26; p = 0.008). In-silico analysis of the c.1810C>T polymorphism suggests that the substitution of the corresponding amino acid residue within the conservative region of the tyrosine kinase domain might theoretically interfere with the functioning of the TrkA protein.ConclusionsNTRK1 c.1810C>T polymorphism appears to be a new independent prognostic factor of poor outcome in neuroblastoma, especially in children under 18 months of age with no MYCN amplification.

Late-onset idiopathic thrombocytopenic purpura correlates with rapid B-cell recovery after allogeneic T-cell-depleted peripheral blood progenitor cell transplantation in children ☆

IDIOPATHIC THROMBOCYTOPENIC PURPURA (ITP) is mediated by IgG or IgM autoantobodies, which bind to the platelet membrane, leading to platelet destruction by the reticuloendothelial system. In the posttransplant setting thrombocytopenia is mostly associated with GvHD, CMV infection, or both. True ITP, independent from GvHD, has been observed occasionally and treated with different modalities: steroids, high-dose intravenous immunoglobulin (IvIG), vincristine, anti-D immunoglobulin, splenectomy, and androgens. There are no data in the literature indicating possible association between ITP and a pattern of immune recovery after allogeneic hematopoietic cell transplantation (HCT). Therefore, two cases of ITP late posttransplant are reported and discussed below.

Standard and intermediate risk acute lymphoblastic leukemia in Poland: A report of the Polish Children's Leukemia/Lymphoma Study Group

A total of 527 children with acute lymphoblastic leukaemia (ALL) from the most frequent risk groups: standard risk group (SRG) and intermediate risk group (IRG) were treated between 1987 and 1991 according to an intensified treatment program (based on the BFM protocol) including the use of an intermediate dose of methotrexate in the IRG. A comparison of the treatment results in this group from 513 children treated between 1981 and 1987 indicates that the chance for a 6 year event‐free survival has increased to 73% (previously 55%).

Clinical value of the flow cytometric method for measuring lymphocyte subset activation: spontaneous activation of T-cell subpopulations is associated with acute GvHD.

Thymidine ((3)H-TdR) incorporation remains the most commonly used method to quantifying T-cell proliferation. This method, however, does not provide information about specific lymphocyte subpopulations responding to different stimuli. In our study, we modified previously described nonradioactive flow-cytometric T-cell activation assay measuring the expression of a CD69+ antigen on T-cell subsets and applied it to analysis of lymphocyte subsets activation/proliferation in children after allogeneic hematopoietic cell transplantation (HCT). We compared the percentage of spontaneously activated lymphocyte subpopulations (background) and the percentage of PHA-P, PWM, and SEB-stimulated cell subsets from two groups of patients: group 1, children with Graft versus Host Disease (GvHD) and group 2, children without any signs of GvHD at the time of analysis. High rate of spontaneous T-cell subset activation was found in group 1 with CD3+CD8+Ts cells being the most affected cell population. High background activation of Th and B cells correlated with the occurrence of autoimmune phenomena posttransplant. Rapid quantification of CD69+ expression on unstimulated and stimulated T-cell subsets proved to be a valuable method for monitoring children after allogeneic HCT. High proportion of activated, unstimulated Ts cells observed in the GvHD group may underline the critical role of CD3+CD8+ cells in the pathogenesis of GvHD. Thus in future immunosuppressive therapy may be adjusted according to the proportion of activated Ts cells.

Monitoring of hematopoietic chimerism after sex-mismatched allogeneic stem cell transplantation (alloSCT) by dual-color FISH analysis of X and Y chromosomes

Hematopoietic chimerism was monitored in 18 patients with various diseases after gender-mismatched allogeneic stem cell transplantation (alloSCT). To detect host and donor cells, FISH analysis of sex chromosomes was applied. X and Y chromosomes were detected simultaneously in interphase nuclei by two-color probes. Chimerism was examined sequentially in post-transplant peripheral blood and bone marrow as well as in purified T cells. Patients with complete donor or decreasing host chimerism have not rejected or relapsed but experienced a high incidence of acute graft versus host disease (aGvHD). The clinical value of stable mixed chimerism detection remains uncertain. However, it appears to be associated with a lower risk of aGvHD. Three patients with an increase in host cells rejected their grafts. The immunotherapy was introduced to four other patients with increasing host chimerism. All of them responded, however, one relapsed in CNS despite the conversion to complete donor chimerism in both bone marrow and peripheral blood. We concluded that two-color FISH analysis of sex chromosomes was a valuable tool for chimerism monitoring and provided significant clinical data.