Low-Frequency Blood Group Antigens in Switzerland.

BACKGROUND: High-frequency blood group antigens (HFA) are present in >90% of the human population, according to some reports even in >99% of individuals. Therefore, patients lacking HFA may become challenging for transfusion support because compatible blood is hardly found, and if the patient carries alloantibodies, the cross-match will be positive with virtual every red cell unit tested. METHODS: In this study, we applied high-throughput blood group SNP genotyping on >37,000 Swiss blood donors, intending to identify homozygous carriers of low-frequency blood group antigens (LFA). RESULTS: 326 such individuals were identified and made available to transfusion specialists for future support of patients in need of rare blood products. CONCLUSION: Thorough comparison of minor allele frequencies using population genetics revealed heterogeneity of allele distributions among Swiss blood donors which may be explained by the topographical and cultural peculiarities of Switzerland. Moreover, geographically localized donor subpopulations are described which contain above-average numbers of individuals carrying rare blood group genotypes.

MNSs genotyping by MALDI-TOF MS shows high concordance with serology, allows gene copy number testing and reveals new St(a) alleles.

Results of genotyping with true high-throughput capability for MNSs antigens are underrepresented, probably because of technical issues, due to the high level of nucleotide sequence homology of the paralogous genes GYPA, GYPB and GYPE. Eight MNSs-specific single nucleotide polymorphisms (SNP) were detected using matrix-assisted laser desorption/ionization, time-of-flight mass spectrometry (MALDI-TOF MS) in 5800 serologically M/N and S/s pre-typed Swiss blood donors and 50 individuals of known or presumptive black African ethnicity. Comparison of serotype with genotype delivered concordance rates of 99·70% and 99·90% and accuracy of genotyping alone of 99·88% and 99·95%, for M/N and S/s, respectively. The area under the curve of peak signals was measured in intron 1 of the two highly homologous genes GYPB and GYPE and allowed for gene copy number variation estimates in all individuals investigated. Elevated GYPB:GYPE ratios accumulated in several carriers of two newly observed GYP*401 variants, termed type G and H, both encoding for the low incidence antigen St(a). In black Africans, reduced GYPB gene contents were proven in pre-typed S-s-U- phenotypes and could be reproduced in unknown specimens. Quantitative gene copy number estimates represented a highly attractive supplement to conventional genotyping, solely based on MNSs SNPs.

Peripheral blood CD56(bright) NK cells respond to stem cell factor and adhere to its membrane-bound form after upregulation of c-kit.

CD56(bright) NK cells express receptors for IL-2, IL-7, IL-15, and SCF. We found that human peripheral blood CD56(bright) NK cells responded to IL-2, IL-7, IL-15 by phosphorylating STAT-5, ERK, and Akt but did not respond to SCF. However, CD56(bright) NK cells in culture upregulated c-kit transcription three to fourfold, which led to a steady increase in c-kit and a concomitant acquisition of responsiveness to SCF. After 44 h, CD56(bright) NK cells had upregulated c-kit approximately 20-fold and phosphorylated ERK and Akt in response to SCF concentrations well below levels present in plasma. CD56(bright) NK cells cultured in IL-15 maintained c-kit transcription/expression at ex vivo levels and did not become responsive to SCF. Furthermore, SCF-responsive, CD56(bright) c-kit(high) NK cells swiftly downregulated c-kit and stopped responding to SCF after IL-15 stimulation. However, commitment of CD56(bright) NK cells to a c-kit-negative, SCF-unresponsive state did not occur, as after 5 days of culture, withdrawal of IL-15 restored c-kit to maximal levels and reestablished SCF-responsiveness. CD56(bright) NK cells that had upregulated c-kit firmly adhered to COS cells transfected with the membrane form of SCF. Furthermore, SCF signaling significantly increased the capacity of CD56(bright) NK cells to degranulate. Collectively, our data suggest that c-kit on human CD56(bright) NK cells is a functional receptor that is downregulated in peripheral blood, possibly to render CD56(bright) NK cells unresponsive to the SCF therein.

Comprehensive metagenomic analysis of glioblastoma reveals absence of known virus despite antiviral-like type I interferon gene response.

Glioblastoma is a deadly malignant brain tumor and one of the most incurable forms of cancer in need of new therapeutic targets. As some cancers are known to be caused by a virus, the discovery of viruses could open the possibility to treat, and perhaps prevent, such a disease. Although an association with viruses such as cytomegalovirus or Simian virus 40 has been strongly suggested, involvement of these and other viruses in the initiation and/or propagation of glioblastoma remains vague, controversial and warrants elucidation. To exhaustively address the association of virus and glioblastoma, we developed and validated a robust metagenomic approach to analyze patient biopsies via high-throughput sequencing, a sensitive tool for virus screening. In addition to traditional clinical diagnostics, glioblastoma biopsies were deep-sequenced and analyzed with a multistage computational pipeline to identify known or potentially discover unknown viruses. In contrast to the studies reporting the presence of viral signatures in glioblastoma, no common or recurring active viruses were detected, despite finding an antiviral-like type I interferon response in some specimens. Our findings highlight a discrete and non-specific viral signature and uncharacterized short RNA sequences in glioblastoma. This study provides new insights into glioblastoma pathogenesis and defines a general methodology that can be used for high-resolution virus screening and discovery in human cancers.