Luminex® xMAP® technology is an effective strategy for high-definition human leukocyte antigen typing of cord blood units prior to listing.

INTRODUCTION: Allele-level donor-recipient match at HLA-A, HLA-B, HLA-C and HLA-DRB1 loci impacts the outcome after cord blood transplantation for hematologic malignancies and modifies the strategy of donor selection. High definition of both class I and II HLA loci at time of listing is a way to improve the attractiveness of cord blood bank inventories, reducing the time for donor search and procurement and simplifying donor choice, in particular, for patients of non-European heritage. METHODS: In 2014, Luminex® xMAP® technology was introduced in our laboratory practice and was applied to cord blood units typing. In this study, we evaluated the impact of this strategy in comparison with the platform in use until 2013, relying on LiPA reverse polymerase chain reaction-sequence-specific oligonucleotide (revPCR-SSO) plus polymerase chain reaction-sequence-specific primer (PCR-SSP). RESULTS: In 2014, the time for testing was shorter (141 vs 181 days on average), the number of test repetitions was lower (in particular for HLA-A locus, p = 0.026), and the cost reduced (240.7 vs 395.6 euros per unit on average) compared to 2013, demonstrating that Luminex xMAP technology is superior to the previous approach. CONCLUSION: Luminex xMAP platform has useful application in cord blood banking programs, to achieve high-definition HLA typing of cord blood units at the time of banking in a quick, accurate, and cost-effective manner.

The plasma levels of soluble HLA-G molecules correlate directly with CD34+ cell concentration and HLA-G 14bp insertion/insertion polymorphism in cord blood donors.

BACKGROUND: Cord blood provides haematopoietic stem cells for allogeneic transplantation and, thanks to the naivety of its immune system, has several advantages over other sources of stem cells. In the transplantation setting, the presence of immunosuppressive human leucocyte antigen (HLA)-G molecules has been advocated to prevent both rejection and Graft-versus-Host disease. HLA-G is physiologically expressed throughout pregnancy and is contained in cord blood at birth. Moreover, it has recently been reported that not only cord blood mesenchymal cells, but also CD34+ cell progenies produce soluble HLA-G (sHLA-G). We tried to identify the largest producer of sHLA-G among 85 healthy cord blood donors at Pavia Cord Blood Bank, correlating the sHLA-G concentration with the HLA-G 14bp insertion/deletion (INS/DEL) genotype and CD34+ cell concentration. MATERIALS AND METHODS: We measured sHLA-G levels in 36 cord blood plasma stored at -20 °C for 2 months and 49 cord blood plasma stored at -196 °C for 4-6 years, by enzyme-linked immunosorbent assay. All cord blood donors were genotyped for the HLA-G 14bp INS/DEL polymorphism by polymerase chain reaction. For each cord blood unit, we measured the cell concentration by flow cytometry. RESULTS: We did not find differences in sHLA-G levels between cord blood plasma aliquots stored for 4-6 years at -196 °C and cord blood plasma aliquots stored for 2 months at -20 °C. We observed a higher sHLA-G concentration in cord blood plasma donors who carried the HLA-G 14bp INS/INS genotype and had higher CD34+ cell concentrations (P=0.006). DISCUSSION: This is the first report showing that the best cord blood stem cell donor is also the best sHLA-G producer, particularly if genetically characterized by the HLA-G 14bp INS/INS genotype. If the therapeutic role of sHLA-G molecules were to be finally established in the transplantation setting, our data suggest that cord blood plasma donors can provide a safe source of allogeneic sHLA-G immunosuppressive molecules ready for transfusion.