S. Wehner

Chromosomal rearrangements of the human MLL (mixed lineage leukemia) gene are associated with high-risk infant, pediatric, adult and therapy-induced acute leukemias. We used long-distance inverse-polymerase chain reaction to characterize the chromosomal rearrangement of individual acute leukemia patients. We present data of the molecular characterization of 1590 MLL-rearranged biopsy samples obtained from acute leukemia patients. The precise localization of genomic breakpoints within the MLL gene and the involved translocation partner genes (TPGs) were determined and novel TPGs identified. All patients were classified according to their gender (852 females and 745 males), age at diagnosis (558 infant, 416 pediatric and 616 adult leukemia patients) and other clinical criteria. Combined data of our study and recently published data revealed a total of 121 different MLL rearrangements, of which 79 TPGs are now characterized at the molecular level. However, only seven rearrangements seem to be predominantly associated with illegitimate recombinations of the MLL gene (≈ 90%): AFF1/AF4, MLLT3/AF9, MLLT1/ENL, MLLT10/AF10, ELL, partial tandem duplications (MLL PTDs) and MLLT4/AF6, respectively. The MLL breakpoint distributions for all clinical relevant subtypes (gender, disease type, age at diagnosis, reciprocal, complex and therapy-induced translocations) are presented. Finally, we present the extending network of reciprocal MLL fusions deriving from complex rearrangements.

OBJECTIVE: Lipoprotein(a)-hyperlipoproteinemia (Lp(a)-HLP) along with progressive cardiovascular disease has been approved as indication for regular lipoprotein apheresis (LA) in Germany since 2008. We aimed to study the long-term preventive effect of LA and to assess hypothetical clinical correlations of apolipoprotein(a) (apo(a)) by analyzing genotypes and phenotypes. APPROACH AND RESULTS: This prospective observational multicenter study included 170 patients with Lp(a)-HLP and progressive cardiovascular disease (48.9 years median age at diagnosis) despite other cardiovascular risk factors, including low-density lipoprotein cholesterol had maximally been treated (mean baseline low-density lipoprotein cholesterol: measured, 2.56 mmol/L [98.9 mg/dL] and corrected, 1.72 mmol/L [66.3 mg/dL]). Patients were prospectively investigated during a 5-year period about annual incidence rates of cardiovascular events. In addition, apo(a) isoforms and polymorphisms at the apo(a) gene (LPA) were characterized. One hundred fifty-four patients (90.6%) completed 5 years of follow-up. Mean Lp(a) concentration before commencing regular LA was 108.1 mg/dL. This was reduced by a single LA treatment by 68.1% on average. Significant decline of the mean annual cardiovascular event rate was observed from 0.58±0.53 2 years before regular LA to 0.11±0.15 thereafter (P<0.0001); 95.3% of patients expressed at least 1 small apo(a) isoform. Small apo(a) isoform (35.2%) carrying phenotypes were not tagged by single-nucleotide polymorphisms rs10455872 or rs3798220. CONCLUSIONS: Results of 5 years of prospective follow-up confirm that LA has a lasting effect on prevention of cardiovascular events in patients with Lp(a)-HLP. Patients clinically selected by progressive cardiovascular disease were characterized by a highly frequent expression of small apo(a) isoforms. Only Lp(a) concentration seemed to comprehensively reflect Lp(a)-associated cardiovascular risk, however.

Previous reports demonstrated a relationship between proliferation potential and trilineage differentiation in mesenchymal stromal cell-derived clones generated using plastic adherence (PA-MSCs). However, there are no reports presenting a clonal analysis of the proliferative potential, differentiation potential and allosuppressive effects of human mesenchymal stromal cell subsets. In this study, we performed a clonal analysis of mesenchymal stromal cells generated from human CD271(+) bone marrow mononuclear cells (CD271-MSCs). After transfection with the gene encoding green fluorescent protein, the cells were single-cell sorted and cultured for 2-4 weeks. A population doubling analysis demonstrated that 25% of CD271-MSC clones are fast-proliferating clones compared to only 10% of PA-MSC clones. Evaluation of the allosuppressive potential demonstrated that 81.8% of CD271-MSC clones were highly allosuppressive compared to only 58% of PA-MSC clones. However, no consistent correlation was observed between allosuppression and proliferative potential. Prostaglandin E2 levels were positively correlated with the allosuppressive activity of individual clones, suggesting that this molecule may be a useful predictive biomarker for the allosuppressive potential of mesenchymal stromal cells. In contrast, inhibitory studies of indoleamine 2,3 dioxygenase indicated that none of the clones used this enzyme to mediate their allosuppressive effect. Differentiation studies revealed the presence of tripotent, bipotent and unipotent CD271-MSC and PA-MSC clones which suppressed the allogeneic reaction to differing extents in vitro. In conclusion, our findings demonstrate differences between CD271-MSCs and PA-MSCs and indicate that neither proliferation potential nor differentiation potential represents a consistent predictive parameter for the immunomodulatory effects of either type of mesenchymal stromal cells.

Neuroblastoma (NB) is a solid tumor of childhood with a relatively bad prognosis, with the exception of young infants (less than 1 year), in whom spontaneous regression of tumor burden occurs. The reasons for this are still unknown but immune mechanisms may be involved. In this study, we have examined the ability of several monoclonal antibodies (MoAbs), which recognize markers predominantly expressed on human haematopoietic cells, to react with four human neuroblastoma cell lines (UKF-NB 1-4) and SK-N-SH as control cell line. In order to define the phenotype of NB cells, we used a large panel of MoAbs consisting of 2 major groups: a) well characterized MoAbs raised against antigens of neuroectodermal origin from the Kemshead-serie (e.g. UJ 13A, UJ 127.II, UJ 167.11, UJ 181.4, UJ 223.8, A2B5), b) monoclonal antibodies which have been considered to react with haematopoietic cells (HLA-DR and anti-CD-molecules CD1, CD7, CD9, CD10, CD13, CD16, CD19, CD20, CD24, CD57). The phenotypic analyses were performed at various times of culture by an immunoenzymatic procedure (APAAP-technique). Most of the MoAbs used against neuroblastoma cells showed a strong reactivity pattern with the NB cell lines. None of the antibodies against T-lymphocytes bound to any of the NB cells assayed in our study, with the exception of anti-CD 1. On the contrary, B-cell markers BA-2 (CD9) and BA-1 (CD24) cross-reacted with the NB cells just as well as the marker for NK-cells (CD57), but they did not express reactivity with Leu-11b (CD16), anti-CALLA (CD10) and anti-HLA-DR.