Search

One hundred and ninety-one patients with acute leukaemia who received bone marrow from HLA-A, -B and -DR identical unrelated donors and were reported to EBMT and/or IMUST, were matched with 382 patients receiving autologous bone marrow for diagnosis, age, stage of disease and year of transplantation. Transplant-related mortality (TRM) was significantly higher in recipients of unrelated marrow compared to autograft recipients, 44 +/- 4% (+/- 95% confidence interval) and 15 +/- 3% at 2 years in the two groups, respectively (P < 10(-4)). In contrast, relapse probability was lower in recipients of unrelated marrow, being 32 +/- 5% at 2 years compared to 55 +/- 3% in recipients of autografts (P < 10(-4)). Two-year leukaemia-free survival (LFS) in patients with acute lymphoblastic leukaemia was 39 +/- 5% and 32 +/- 3% in the two groups, respectively. Among patients with acute myeloid leukaemia (AML), the corresponding figures were 36 +/- 6% and 46 +/- 5% in the two groups, respectively (P = NS). In AML in first remission (CR-1), the 2-year survival was 42 +/- 10% in recipients of unrelated bone marrow, compared to 69 +/- 8% in autograft recipients (P = 0.008). When all patients with acute leukaemia were included, the 2-year LFS was 38% in recipients of unrelated marrow, compared to 37% in autograft recipients (NS). In conclusion, this retrospective analysis supports the design of a prospective randomized study in patients with high-risk/advanced acute leukaemia who lack a suitable related bone marrow donor, to ascertain which of the two strategies, if any, should be favoured.

Cryopreservation techniques for umbilical cord blood (UCB) have been based on methods established for marrow (BM) and peripheral blood progenitor cells (PBPC) with varying degrees of success. The aim of this study was to optimise cryopreservation of UCB haemopoietic cells based on sound cryopreservation principles. UCB samples were cryopreserved with different combinations of DMSO and hydroxyethyl starch (HES) by a variety of freezing protocols. After cooling at 1 degree C/min in solutions containing 4% HES and various concentrations of DMSO there was a dramatic fall in CD34+ recovery from 85.4% (s.d. 28.4) to 12.2% (s.d. 10.0) as DMSO concentration was reduced from 5 to 2.5%. Varying HES concentration in solutions containing 5% DMSO did not have a significant effect on CD34+ cell recovery. Increasing cooling rate from 1 to 10 degrees C/min significantly reduced CD34+ recovery (P < 0.0001) while increasing DMSO concentration up to 10% had little effect (P = 0.8, two-way ANOVA). Good recovery of UCB CD34+ cells can be achieved with 5-10% DMSO at a controlled cooling rate of 1 degrees C/min. There was a significant difference (P < 0.0001) in the apparent recovery of CD34+ cells between paired aliquots thawed in the presence (recovery = 76.8%, s.d. 26.0) and absence (32.5%, s.d. 18.7) of DNase. In conclusion, conditions for cryopreserving UCB for clinical banking that yield optimal recovery of CD34+ cells have been established.

Unrelated donor bone marrow transplantation is increasingly used to treat haemopoietic disorders where no HLA-identical sibling is available. The International Marrow Unrelated Search and Transplant Study has collected core data on consecutive unrelated donor BMT (UD-BMT) and HLA-identical sibling donor BMT (ID-BMT) performed in 46 participating centres world-wide between March 1989 and February 1993. Eighteen UD-BMT were performed in the first 6-month period in 14 participating centres, while in the last period there were 103 UD-BMT in 46 centres. The percentage of BMT recipients with the following diagnoses were: bone marrow failure UD-BMT 15% and ID-BMT 11%; AML 13% and 27%; ALL 18% and 17%; CML 48% and 31%; and other diseases 7% and 14%. Thirty-eight per cent of UD-BMT recipients had advanced disease compared with only 23% of ID-BMT recipients. Thirty six per cent of UD-BMT compared with 21% of ID-BMT recipients were under 16 years old. More extreme differences in pre-transplant clinical characteristics between UD and ID-BMT recipients were found when diagnosis and stage of disease were considered together. This survey indicates how UD and ID-BMT are currently used in the treatment of haematological disease; however, longer follow-up is required to assess the value of UD-BMT in the management of patients with bone marrow disorders.

We have used a high responder rat model to examine the role that non-MHC antigens play in corneal graft rejection. Recipients were backcross animals derived from a cross between two inbred strains, which mimicked the human outbred population in that donor and recipient could be matched or mismatched for MHC antigens, while non-MHC mismatches were variable and unknown. All mismatched grafts and 87% of matched grafts were rejected (median survival 11 and 17 days respectively). The high incidence of rejection of matched grafts indicates that several independently segregating non-MHC genes play a role in rejection. Moreover, the immune response to matched grafts appeared resistant to immunosuppression, suggesting that matching does not permit reduced dosage of immunosuppressants. A mechanism is discussed whereby matching at the class II locus may enhance presentation of mismatched histocompatibility antigens or viral peptides derived from infected graft cells, thereby prejudicing graft survival.

Outcomes of searches for unrelated bone marrow donors were analysed to identify factors influencing the probability of identifying an HLA-matched donor and proceeding to an unrelated donor bone marrow transplant (UD-BMT). Between March 1989 and January 1991, 649 unrelated marrow donor searches were entered into the study. Searches were referred from transplant centres in Europe and North America to the Anthony Nolan Research Centre panel and/or the British Bone Marrow and Platelet Donor Panel, two predominantly Caucasian donor registries. Patient immunogenetic and clinical characteristics were documented on study search request forms and search outcomes were monitored at the donor registry. Data were analysed using proportional hazards regression. Major factors predicting favourable search outcomes were patient common Caucasian HLA phenotype and Caucasian ethnic group. Probability of search failure was increased by advanced disease, rare Caucasian HLA phenotype and referral to the smaller registry. Search failure frequently occurred at the mixed lymphocyte reaction stage. This study illustrates the relative roles of clinical, immunogenetic and registry factors in determining the outcome of searches. The information may be used to devise strategies to locate HLA-matched donors for a higher proportion of patients for whom UD-BMT is the preferred treatment.

The International Marrow Unrelated Search and Transplant (IMUST) Study has prospectively assessed outcome of unrelated donor BMT (UD-BMT) in comparison with a matched cohort of patients treated by HLA-identical sibling BMT (ID-BMT). We report an interim analysis of the first 165 UD-BMT and 368 ID-BMT. Eighty-two percent of UD-BMT pairs were matched by serology for HLA-A, B and DR, 10% were less well matched and HLA matching data was incomplete in 8%. The Kaplan-Meier estimated probability of survival until day 400 was 0.42 (95% confidence limits 0.33-0.51) after UD-BMT and 0.62 (0.56-0.68) after ID-BMT (p = < 0.001). Probability of engraftment by day 100 was 0.90 (0.85-0.95) and 0.95-0.99) after UD-BMT and ID-BMT, respectively (p = < 0.001). Cumulative probability of acute GVHD by day 100 was 0.52 (0.45-0.60) and 0.42 (0.37-0.47) after UD-BMT and ID-BMT, respectively (p = 0.009). After UD-BMT, 52% of patients with early disease survived until day 400 (40-64%) and 27% (14-40%) with advanced disease (p = < 0.001). Multifactorial analysis of survival showed success was related to the centre's experience of UD-BMT and this effect was modified by conditioning protocol. Increased probability of survival after UD-BMT in centres with most experience of the procedure is novel finding. We conclude UD-BMT is a more difficult procedure than ID-BMT but results are acceptable in patients with early disease and when UD-BMT is carried out in experienced centres.

The use of DNA restriction fragment length polymorphism (DNA-RFLP) typing for HLA-DR and DQ genes was assessed in 96 patients who were HLA-A,B and DR matched by serology with one or more potential unrelated marrow donors (UD). Two hundred recipient-donor pairs from 10 transplant centres in the UK were studied. DNA-RFLP revealed serological errors in HLA-DR typing and identified additional recipient-donor mismatches. Of the 200 allegedly serologically matched pairs, 55 (28%) were mismatched for HLA-DR and/or DQ by DNA-RFLP typing. Of the 200 pairs, 68 (34%) mixed lymphocyte reactions (MLR) were negative and 132 (66%) positive. There was a significant correlation between DNA-RFLP defined mismatch and MLR positivity. However quantitative studies revealed no trend towards increasing MLR relative response index (RRI) with cumulative RFLP defined mismatch (i.e. for DR plus DQ compared with DR or DQ alone). RFLP matching for HLA-DR and DQ failed to predict a negative MLR. The RRI in the graft-versus-host direction was greater in RFLP matched pairs who carried HLA-DR4 than in matched pairs lacking DR4, suggesting that failure of RFLP to characterize DR4 subtypes was one reason why routine prediction of a negative MLR was not possible. Despite these limitations we have shown that DNA-RFLP is a reliable method for HLA-DR, DQ typing in routine UD searches in diverse clinical centres. By reducing the number of UD tested in MLR, RFLP typing can substantially reduce the work involved in donor selection.

In a preliminary study we have shown that optimally collected human umbilical cord (HUC) blood cells grow significantly better in long term cultures (LTC) than normal adult marrow cells (NBM) p = 0.0007. The LTC findings are supported by the observation in clonogenic assay that a similar number of GM-CFC colonies can be grown from HUC blood and NBM mononuclear cells (MNC). Also there is a trend towards a higher proportion of primitive erythroid (BFU-E) and primitive megakaryocyte colonies (MK-CFC containing greater than 20 cells) in HUC blood compared with NBM. We suggest that further work on the feasibility of a HLA typed, cryopreserved HUC blood bank as a source of unrelated haemopoietic 'stem' cells for clinical transplantation is indicated.

Eleven leukaemic patients and 43 potential unrelated marrow donors were typed serologically, tested in mixed lymphocyte reaction (MLR) and typed by restriction fragment length polymorphism (RFLP) analysis. RFLP typing data were compared with DR serology and MLR results. Eleven of the 54 individuals showed discrepancies between DR serology and RFLP DR assignment. RFLP DR/DQ mismatch always correlated with positive MLR, but RFLP identity was present in both MLR negative and MLR positive pairs. RFLP typing cannot reliably predict a negative MLR response, but we suggest that it should be used in the selection of unrelated marrow donors to exclude mismatched donors from testing in the MLR. This will facilitate donor searches by reducing the number of MLR performed.