Patients with early relapse of primary hemophagocytic syndromes or with persistent CNS involvement may benefit from immediate hematopoietic stem cell transplantation

Primary hemophagocytic syndromes represent a group of rare immunodeficiencies, which are characterized by development of life-threatening systemic inflammatory manifestations, so-called accelerated phases. Immunosuppressive therapies are only temporarily effective to control this complication and the prognosis is dismal unless treated by hematopoietic SCT (HSCT). At present, optimal modalities of this potentially curative approach remain incompletely defined. In this study, we analyzed our experience in 18 patients with primary hemophagocytic syndromes treated since 1984 in our center by HSCT. Ten of these patients had previously developed accelerated phases and were in remission at the time of HSCT, whereas five patients had findings of active disease, with two cases in early phases of recurrences of less than 2 weeks duration and three cases with persistent central nervous system disease, whereas three patients had never experienced accelerated phases. In the group with active disease, four of five patients are long-term survivors and are well, whereas one patient died of CMV pneumonia. This outcome compares favorably with results in patients transplanted in remission, where 6 of 10 are long-term survivors. Our findings indicate that HSCT can have a favorable prognosis even in patients with active disease of primary hemophagocytic syndrome.

Genotype-phenotype study of familial haemophagocytic lymphohistiocytosis due to perforin mutations

BACKGROUND

PRF1 gene mutations are associated with familial haemophagocytic lymphohistiocytosis type 2 (FHL2). Genotype-phenotype analysis, previously hampered by limited numbers of patients, was for the first time performed by data pooling from five large centres worldwide.

PATIENTS AND METHODS

Members of the Histiocyte Society were asked to report cases of FHL2 on specific forms. Data were pooled in a common database and analysed.

RESULTS

The 124 patients had 63 different mutations (including 15 novel mutations): 11 nonsense, 10 frameshift, 38 missense and 4 in-frame deletions. Some mutations were found more commonly: 1122 G-->A (W374X), associated with Turkish origin, in 32 patients; 50delT (L17fsX22) associated with African/African American origin, in 21 patients; and 1090-91delCT (L364fsX), in 7 Japanese patients. Flow cytometry showed that perforin expression was absent in 40, reduced in 6 and normal in 4 patients. Patients presented at a median age of 3 months (quartiles: 2, 3 and 13 months), always with fever, splenomegaly and thrombocytopenia. NK activity was absent in 36 (51%), <or=2% in 18 (26%), 3-<or=5% in 10 (14%), >5% in 4 (6%), "reduced" in 2 (3%) (not reported, n = 54). Nonsense mutations were significantly associated with younger age at onset (p<0.001) and absent natural killer activity (p = 0.008).

CONCLUSION

PRF1 mutations are spread over the functional domains. Specific mutations are strongly associated with Turkish, African American and Japanese ethnic groups. Later onset and residual cytotoxic function are observed in patients with at least one missense mutation.

Denaturing HPLC for identification of clonal T-cell receptor gamma rearrangements in newly diagnosed acute lymphoblastic leukemia

BACKGROUND

Denaturing HPLC (DHPLC) can be used to screen DNA for known and unknown mutations. We describe a novel, HPLC-based method for discrimination among polyclonal, oligoclonal, and/or clonal T-cell receptor gamma (TCR-gamma) rearrangements in samples from children with newly diagnosed acute lymphoblastic leukemia.

METHODS

TCR rearrangements were PCR amplified from initial leukemic samples and, after heteroduplex-induction, the clonality status of each product was evaluated. To attain this, we used DHPLC on a high-resolution micropellicular matrix. Running conditions were established by melting-curve analysis of known clonal and polyclonal products and melting-point prediction software. Elution profiles were studied at 50 degrees C (native) and, to achieve optimal separation, at different column temperatures between 56 and 64 degrees C.

RESULTS

For VgammaI-Jgamma1.3/2.3 rearrangements, an analysis temperature of 60 degrees C with a linear triethylammoniumacetate-acetonitrile gradient separated clonal bands from the polyclonal background amplification. Less than 15% clonal PCR product was detectable in mixtures of initial leukemic cell DNA and polyclonal DNA. Biallelic rearrangements produced two sharp peaks. Clonality of PCR products from 100 initial leukemic samples was completely identified in all investigated cases.

CONCLUSIONS

Heteroduplex analysis with standardized DHPLC conditions simplifies the detection of unknown clonal or polyclonal TCR rearrangements in newly diagnosed leukemias. Clonal targets for detection of minimal residual disease are available after a short, automated analysis of PCR amplified rearrangements.

Variant translocations in sporadic Burkitt's lymphoma detected in fresh tumour material: analysis of three cases

Burkitt's lymphoma/Burkitt cell leukaemia (BL) is characterized by one of the reciprocal translocations involving the MYC oncogene on chromosome 8 and one of the immunoglobulin (Ig) loci on chromosomes 14, 2 or 22. In the few cell lines with the variant translocations t(2;8) and t(8;22) reported to date, the breakpoints on chromosome 8 were located downstream of MYC at a distance of up to 300 kb and more. Here, we describe three new cases with variant translocations. Fresh tumour material from paediatric patients, negative for the common translocation t(8;14), was analysed using a long-distance (LD) polymerase chain reaction (PCR) approach. On chromosome 8, primers were derived from several different regions 3' of MYC, and on chromosomes 2 and 22 from the constant regions of the Ig kappa (Igkappa) and lambda (Iglambda) genes. One translocation t(2;8) and two t(8;22) were detected. In the t(2;8) translocation, the chromosome 8 breakpoint was located 2 kb 3' of the MYC exon 3 and the chromosome 2 breakpoint within an unrearranged Igkappa locus. The breakpoints of the two translocations t(8;22) were detected 16 kb for one and 58 kb for the other downstream of MYC. Sequencing the t(8;22) translocation in one of the cases showed hypermutation of the translocated variable Vlambda4b gene. The presence of hypermutated variable regions in the t(8;22) case suggests germinal centre B cells as the origin of this translocation. The t(2;8) translocation is the first description of a translocation t(2;8) involving an unrearranged Igkappa gene. A mechanism different from V-J recombination and somatic hypermutation has to be proposed for this translocation.

[Minimal residual disease analysis in acute lymphoblastic leukemia of childhood within the framework of COALL Study: results of an induction therapy without asparaginase]

The detection of minimal residual disease (MRD) is a major prognostic factor for treatment in acute lymphoblastic leukemia (ALL) of childhood. Several groups showed the predictive value of MRD after 5 weeks of chemotherapy (at the end of induction therapy). Patients with more than 1 leukemic cells in 100 cells (> or = 10(-2)) at this time-point have a significantly higher relapse rate. The MRD measurement has been shown to be an independent prognostic factor at several time points in the BFM study (ALL-BFM 90) as well as in the EORTC study. The aim of our investigations was the detection of MRD at the end of induction therapy within the COALL studies which is different from the above studies. In the COALL studies, therapy starts with a 1 week DNR prephase (24 h infusion on day one) and i.th. MTX. Induction therapy consisted of 3 drugs over a period of 4 weeks (Prednisolone, Vincristine and Daunorubicin), asparaginase is given later in consolidation. At the end of induction therapy, bone marrow was obtained for cytomorphologic and molecular analysis.

PATIENTS AND METHODS

We investigated bone marrow samples from 76 patients. All patients were in morphologic remission at the end. of induction therapy. For MRD analysis, DNA was isolated from bone marrow mononuclear cells. Clonal T-cell-receptor (TCR) or immunoglobulin gene (IgH) rearrangements were identified by PCR. Monoclonal products were either sequenced directly (TCR) or after excision from high resolution agarose gels. Subsequently patient-specific oligonucleotides for allele-specific PCR were generated. PCR analysis was performed with 1 microgram DNA for each reaction within a semiquantitative matter. This method reached sensitivities down to 10(-5).

RESULTS

Eighty-four percent of the analysed samples were MRD positive at the end of induction therapy. 20 out of 76 patient samples (26%) were highly positive (> or = 10(-2)), 28 patients had levels of about 10(-3) (37%), 16 had levels around 10(-4) (21%) and 12 patients had no detectable residual cells (16%). All analysed 15 T-ALL patients had detectable residual disease at this timepoint. Until now, 5/20 patients with very high MRD level at the end of induction therapy suffered a relapse.

DISCUSSION

Patients with very high MRD level at the end of induction therapy showed an elevated risk of relapse, but the predictive value is much poorer than for example in the BFM 90 MRD-study. We suggest, that a high MRD level at this timepoint results from a different induction therapy compared to the BFM 90 study. In the COALL studies asparaginase is given only after induction therapy to decrease the risk of thrombosis. We would like to conclude that this differences were compensated later during therapy as the event free survival of both studies is similar. In conclusion, an optimal information from MRD studies is strongly associated with the given therapy. Therefore we initiated an additional MRD time-point after the first chemotherapy block in consolidation.

[Detection of translocation t(8;14)(q24;132) in pediatric Burkitt's lymphomas using "long distance" polymerase chain reaction: a new method for diagnosis of Burkitt's lymphomas]

The pediatric Non-Hodgkin's lymphomas are a heterogeneous group of malignancies of B- or T-cell origin. Approximately half of them are characterized as Burkitt's lymphomas. Typically, one of the reciprocal translocations t(8;14)(q24;q32), t(2;8)(p11;q24) or t(8;22)(q24;q11) is seen in the tumor cell, each involving the protooncogene c-myc on chromosome 8. Characteristically, in most patients the translocation occurs between the distal end of the long arm on chromosome 8 (c-myc) and chromosome 14 (immunoglobulin heavy chain locus, IgH). The breakpoint regions are distributed over a wide range of more than 10 Kb on chr. 8 and over several hundred Kb on chr. 14. With standard-PCR, fragments can only be amplified to a size of about 2 Kb. The development of PCR-applications to generate long products up to 20 Kb now allows a detection of these breakpoints. Several primer pairs from different regions of the IgH-gene and the c-myc-gene were tested in each patient. Until now, 20 patients with Burkitt's Lymphoma or B-ALL characterized by L3 morphology were examined. All patients were treated according the protocols of the NHL-BFM '90 or '95 study. In 11/20 patients, recombinations between chromosomes 8 and 14 could be detected with our primer pairs. In serial dilutions of DNA from malignant cells in DNA from healthy controls, sensitivities of one malignant cell in 2 x 10(4) normal cells could be obtained. This method will now allow us to characterize the involved breakpoints more exactly and to analyze patient samples (blood, bone marrow, aphereses products and residual tumors) during or after therapy for the existence of minimal residual tumor cells.

Absence of IL-6 receptor expression in fresh childhood Burkitt's lymphoma cells and induction of IL-6 receptors by Epstein-Barr virus in vitro

Interleukin-6 (IL-6) is a cytokine which is necessary for the differentiation of activated B cells and growth of early haemopoietic progenitors. It is used for ex-vivo expansion of myeloid progenitors in the setting of high-dose chemotherapy with autologous bone marrow transplantation (BMT). Expression of the IL-6 receptor (IL-6R) was examined in six fresh Burkitt's lymphoma (BL) cell preparations and 12 BL cell lines by reverse transcriptase polymerase chain reaction (RT-PCR) and flow cytometry (FCM). Inducibility of IL-6R mRNA expression by Epstein-Barr virus (EBV) was studied by comparing two uninfected cell lines with the same cell lines infected by EBV The phenotype of the BL cells lines was analysed by FCM and by proliferation assays in the presence of anti-IgM antibodies. None of the fresh BL cells expressed the IL-6 receptor. The BL cell lines expressed varying degrees of IL-6R mRNA and protein. In vitro infection of EBV-negative BL cell lines resulted in up-regulation of IL-6R mRNA. There was no proliferative response of the BL cell lines to IL-6, including the cells that expressed the receptor. Compared to uninfected BL cell lines, EBV-infected cell lines and lymphoblastoid cell lines (LCLs) showed a weaker or no response to anti-IgM antibodies, indicating a more mature phenotype of these cells. We conclude that the IL-6 receptor is not expressed in fresh childhood BLs, but only in BL cell lines. EBV infection in vitro leads to an up-regulation of IL-6R mRNA but not to increased proliferation. This makes growth stimulation of contaminating BL cells in the setting of autologous BMT unlikely.

Application of long PCR to detect t(8;14)(q24;q32) translocations in childhood Burkitt's lymphoma and B-ALL

BACKGROUND

Burkitt's lymphoma (BL) and B-ALL are characterized by chromosomal translocations juxtaposing the c-myc gene on chromosome 8 to one of the immunoglobulin loci. Translocations involving the immunoglobulin heavy chain (IgH) on chromosome 14 are found in approximately 75%-90% of these tumors. The breakpoint regions are located over a wide range on both chromosomes.

PATIENTS AND METHODS

To detect the translocations, we developed a PCR method to generate long products. After extraction of genomic DNA (QiaAmp System, Qiagen, Hilden, Germany), DNA was amplified using a mixture of Taq and Pwo polymerases (Boehringer Mannheim, Germany). Several primer pairs from the S mu, JH, CH1 and the C alpha regions on IgH and from exon 1 and intron 1 of the c-myc gene were tested in each patient.

RESULTS

Lymphoma cells from 20 children with Burkitt's lymphoma and B-ALL characterized by FAB-L3 morphology were examined. In 11/20 patients, recombinations between chromosomes 8 and 14 could be detected with our primer pairs. PCR products from 800 to 3700 bp in length were obtained reproducibly. After amplification, the products were characterized by restriction enzyme digestion, hybridization, and in part by direct sequencing.

CONCLUSIONS

This PCR-based method will allow us (1) to determine the localization of chromosomal breakpoints in primary tumor material, (2) to investigate whether distinct breakpoints are associated with treatment outcome, and (3) to detect the presence of minimal residual tumor cells during or after therapy.