BSHI/BTS guidance on crossmatching before deceased donor kidney transplantation.

All UK H&I laboratories and transplant units operate under a single national kidney offering policy, but there have been variations in approach regarding when to undertake the pre-transplant crossmatch test. In order to minimize cold ischaemia times for deceased donor kidney transplantation we sought to find ways to be able to report a crossmatch result as early as possible in the donation process. A panel of experts in transplant surgery, nephrology, specialist nursing in organ donation and H&I (all relevant UK laboratories represented) assessed evidence and opinion concerning five factors that relate to the effectiveness of the crossmatch process, as follows: when the result should be ready for reporting; what level of donor HLA typing is needed; crossmatch sample type and availability; fairness and equity; risks and patient safety. Guidelines aimed at improving practice based on these issues are presented, and we expect that following these will allow H&I laboratories to contribute to reducing CIT in deceased donor kidney transplantation.

Correlation between microsatellite discrepancy scores and transplant outcome after haemopoietic SCT for pediatric ALL.

Microsatellite analyses show that self-reported ethnicity often correlates poorly with true genetic ancestry. As unknown ancestral differences could potentially have an impact on transplant outcome, we developed an average allele length discrepancy (AALD) score to assess allele length discrepancy between donor/recipient (D/R) using microsatellites analysed routinely in post-transplant chimeric assessment. This was then compared with outcome in a homogeneously treated cohort of pediatric patients undergoing high-resolution sibling or matched unrelated donor transplantation for acute lymphoblastic leukemia (ALL). AALD scores formed a numeric continuum ranging from 0 to 1.4 (median 0.76) for sibling pairs and 0.8-2.17 (median 1.6) for high-resolution matched unrelated donor (HR-MUD) pairs. There was a trend for worse OS with increasing AALD score, which reached statistical significance above a threshold of 1.7 for OS. Patients whose transplants had an AALD score of ⩾1.8 had a risk of non-relapse mortality 4.9 times greater (P=0.025) and relapse risk three times greater (P=0.058) than those scoring <1.8. This approach will now be explored in a Centre International for Blood and Marrow Transplantation Research (CIBMTR) study of 750 D/R pairs across all disease groups; if confirmed, it has the potential to improve donor selection for patients with multiple prospective donors.

Improved survival in matched unrelated donor transplant for childhood ALL since the introduction of high-resolution matching at HLA class I and II.

We present the first detailed study analysing OS in BMT for paediatric ALL following the introduction of high-resolution (HR) HLA matching. A total of 356 consecutive paediatric ALL stem cell transplants performed between 1988 and 2007 were reviewed; 80 of them were performed following the introduction of HR HLA class I and class II matching to the transplant programme in 2002. Comparisons of matched unrelated donor (MUD) transplant outcomes before and after this period were made. Matching at the HR level for HLA-A, -B, -C, -DRB1 and -DQB1 (HR-MUD) correlated with a greater than 25% improvement in 2- and 5-year OS in paediatric ALL patients transplanted with MUDs (P=0.009, P=0.005, respectively). Two-year OS for contemporaneous HLA-matched sibling transplants (80.8%) and HR-MUD transplants (78.8%) was equivalent. At 6%, non-relapse mortality (NRM) in MUD transplants since 2002 was significantly reduced compared with previous epochs. Changes in treatment and epoch-dependent improvements in outcome were reviewed for possible confounders to the influence of HR typing using univariate and multivariate analysis.

HLA-A, -B and -DR antigen frequencies of the London Cord Blood Bank units differ from those found in established bone marrow donor registries.

Patients requiring allogeneic stem cell transplantation who do not have an HLA-matched related donor can sometimes obtain an unrelated donor by searching volunteer registries. The majority of donors in the registries are Caucasoid, which results in a lower probability of a non-Caucasoid patient finding a suitable donor. Cord blood is increasingly used as a source of haematopoietic stem cells for allogeneic bone marrow reconstitution and so far the London Cord Blood Bank has banked almost 3000 cord blood units. An analysis of the first 1500 units banked showed that more than 30% of the London Cord Blood Bank units are derived from UK ethnic minorities compared with only 2% of individuals recruited locally for the British Bone Marrow Registry (BBMR). The HLA types found in these cord blood units reflect their ethnic diversity and include: HLA-A34, A36, A80, B75, B61, B53, B78, B81 and B82. The units stored by the London Cord Blood Bank show an HLA profile which differs considerably from that of locally typed adult volunteers for the BBMR panel and this should help to increase the chances of obtaining acceptably HLA-matched donors for patients from ethnic minorities. Bone Marrow Transplantation (2000) 25, 475-481.