Christa Hackl

Mesenchymal stem cells (MSCs) are multipotent progenitor cells exerting immunomodulatory effects on cells of the innate and adaptive immune system. It has been shown that an inflammatory milieu is required for the activation of MSC-mediated immunomodulation, and interferon-γ (IFN-γ) plays an important role in this process. We determined the influence of IFN-γ on human adipose-derived stem cells (ASCs) and human amniotic mesenchymal stromal cells (hAMSCs). We further evaluated the effect of MSCs on stimulated T-cells and peripheral blood mononuclear cells (PBMCs) in a cell-contact independent setting. On IFN-γ treatment, ASCs and hAMSCs possessed significantly higher antiproliferative properties and showed surface characteristics of nonprofessional antigen presenting cells (HLA-DR(+)CD40(med+)CD54(high)) with a possible regulatory phenotype (PD-L1(+)PD-L2(+)). The effect of ASCs and hAMSCs on cytokine secretion and T-cell activation was dependent on stimulation method and cellular context. Although ASCs and hAMSCs highly inhibited cytokine secretion of stimulated PBMCs, this was not observed in the case of purified T-cells. The presence of ASCs even favored the secretion of pro-inflammatory cytokines including IFN-γ by T-cells, although T-cell proliferation was efficiently inhibited. Further, ASCs enhanced the number of CD69(+) T-cells independent of the stimuli and cellular context. Interestingly, ASCs significantly suppressed CD25 expression on phytohemagglutinin stimulated PBMCs but had no effect on αCD3/αCD28 stimulated cells. Depending on the stimulation method and cellular context, immune cells create a specific cytokine milieu in vitro, thus differently influencing MSCs and, in turn, affecting their action on immune cells.

BACKGROUND: Hematopoietic stem-cell transplantation is a well-established treatment in various hematologic malignancies, but the outcome depends on disease relapse, infections, and the development and severity of acute and chronic graft-versus-host disease. Some evidence has revealed an important role for the nonclassical major histocompatibility complex class I molecules in transplantation, most notably human leukocyte antigen (HLA)-E. This study evaluates the impact of HLA-E alleles on transplantation outcome after HLA-matched allogeneic HSCT. METHODS: We genotyped DNA for HLA-E polymorphism from 83 recipients and their respective donors by real-time polymerase chain reaction after melting curve analysis and compared the results with clinical outcome. RESULTS: HLA-E*0103 homozygous patients showed a higher probability of overall survival (P=0.003) and disease-free survival (P=0.001) in a univariate model. Cox regression analysis confirmed HLA-E*0103, 0103 (P=0.006; relative risk 1.12; 95% confidence interval 0.31-1.94) and early stage of disease (P=0.005; relative risk 1.16; 95% confidence interval 0.45-1.86) as independent factors improving overall survival. Moreover, homozygosity for HLA-E*0103 was associated with a significant decreased incidence of transplant-related mortality (P=0.01). CONCLUSIONS: We found an association between HLA-E*0103 homozygosity and the significant reduction of transplant-related mortality in related and unrelated HSCT. The risk of posttransplant complications was significantly reduced when the donor possesses the HLA-E*0103, 0103 genotype, and this was translated in a better overall survival.

BACKGROUND AND OBJECTIVES: Molecular variations of the RHD gene may result in the reduced expression of the D antigen and altered Rh phenotypes. In many occasions, they cannot be typed reliably by standard serological methods. Sequence-based typing is the gold standard to determine rare and unknown RHD genotypes. For this pilot study, sequence-based typing by standard Sanger sequencing was compared to a newly established next-generation sequencing approach based on pyrosequencing. MATERIALS AND METHODS: Twenty-six DNA samples were selected after primary serological testing exhibiting a weak reaction in Rh phenotype. Parallel sequence analysis of the complete coding sequence including adjacent intronic sequences allowed a comparison of the methodical potency in mutation detection of Sanger with next-generation sequencing. RESULTS: Sanger sequencing revealed 39 RHD polymorphisms in 21 of 26 samples in the RHD coding region, while pyrosequencing detected all but two alterations resulting in a concordance rate of 94·9% and clearly revealed a heterozygous compound mutation in one sample with RHDψ and Weak D type 4 alleles. The resolution of cis/trans linkage of polymorphisms and exact characterization of a 37 bp duplication was achieved by next-generation sequencing. CONCLUSION: Our data suggest that next-generation sequencing offers a new development for high-throughput and clonal sequencing for molecular RHD genotyping. However, further attempts in the methodical set-up have to be undertaken prior to validation and introduction as a routine service.