Impact of HLA-A,B,C allele mismatches on outcome after unrelated blood stem cell transplantation in whites.

At our institution the selection of unrelated donors for hematopoietic stem cell transplantation (HSCT) relies on low resolution human leukocyte antigen (HLA)-A,B and high resolution HLA-DRB1,DQB1 DNA-based typing. To answer the question of whether routine high resolution HLA-A,B,C typing might improve HSCT outcome, 171 white "HLA-identical" donor/recipient pairs, as stated by our pretransplant tissue typing routine, were retyped for HLA-A,B,C using sequence based typing (SBT). The numbers of HLA-A,B,C allele mismatches detected by SBT were correlated to established clinical endpoints of HSCT outcome. We found 33.9% of the study transplants to be fully HLA-A,B,C matched, whereas 66.1 % exhibited one through four donor/recipient HLA-A,B,C allele mismatches. However, statistical analysis could not demonstrate an impact of the number of HLA-A,B,C allele mismatches on overall survival and other analyzed endpoints. Thus, our series of white donor/recipient pairs does not suggest the routine use of HLA-A,B,C SBT to improve HSCT outcome substantially.

ATG as part of the conditioning regimen reduces transplant-related mortality (TRM) and improves overall survival after unrelated stem cell transplantation in patients with chronic myelogenous leukemia (CML).

Matched unrelated donor transplants have an increased risk of severe graft-versus-host disease and transplant-related mortality (TRM). ATG has been introduced to decrease GvHD and to facilitate engraftment. We conducted a retrospective analysis of 333 patients with chronic myelogenous leukemia, who were treated with Fresenius ATG (n=145, average=90 mg/kg bw, range 40-90 mg/kg bw) or standard immunosuppression without ATG (n=188). Both groups were comparable regarding distribution of age, sex, HLA-matched vs mismatched donors. ATG Fresenius led to a faster leukocyte engraftment, decreased the incidence of acute GvHD and TRM (P=0.01 and P=0.03) and led to a significant better overall survival (70 vs 57%, P=0.03). We concluded that a prospective randomized study is needed to evaluate the definite role of ATG in hemopoietic stem cell transplantation.

Second German consensus on immunogenetic donor search for allotransplantation of hematopoietic stem cells.

The present paper summarizes the results of the second German consensus meeting on immunogenetic donor search for allotransplantation of hematopoietic stem cells held in Essen in November 1999 under the auspices of the German Society for Immunogenetics (DGI) and the German Working Party for Blood and Marrow Transplantation (DAG-KBT). Immunogeneticists and transplant physicians from all over the country agreed to update the national standards for: (1) search strategy including the role of unrelated and extended family donor search after unsuccessful core family donor search, (2) histocompatibility loci to be typed, (3) histocompatibility typing techniques to be used (HLA serology vs DNA-based HLA typing, cellular tests, serum cross-match), and (4) acceptable HLA mismatches in the context of a defined underlying disease, donor type, and conditioning regimen.

Transplant activities in Germany in 1998--a survey facilitated by the National Registry for Hemopoietic Stem Cell Transplantation.

To improve the infrastructure of hemopoietic stem-cell transplantations in our country, the German Registry for Hemopoietic Stem-Cell Transplantations (DRST) was established in 1998. The present paper summarizes the current status of the DRST and gives a survey of transplant activities in Germany in 1998 in terms of transplant units, transplant types, transplant frequencies and underlying diseases.

German consensus on immunogenetic donor search for transplantation of allogeneic bone marrow and peripheral blood stem cells.

In Germany allotransplantation of bone marrow or peripheral blood stem cells is presently performed by 34 different teams operating more or less independently. Thus, strategies of immunogenetic donor search, use of the various tissue typing techniques and policy on acceptable HLA mismatches in related and unrelated settings may vary considerably from one transplant centre to another. This paper summarises the results of the first German consensus meeting on immunogenetic donor search for bone marrow/peripheral blood stem cell grafting. The main goal of the participating transplant physicians and immunogeneticists was to define national standards for the above issues.

Transplantation of filgrastim-mobilized peripheral blood stem cells from HLA-identical sibling or alternative family donors in patients with hematologic malignancies: a prospective comparison on clinical outcome, immune reconstitution, and hematopoietic chimerism.

The clinical results, cellular immune reconstitution, and hematopoietic chimerism obtained after transplantation of recombinant human granulocyte colony-stimulating factor mobilized allogeneic peripheral blood stem cells (PBSCs) from genotypically human leukocyte antigen (HLA)-identical sibling (n = 36) or alternative family donors (n = 24) were prospectively compared in patients with hematologic malignancies. Thirty-two of 34 evaluable patients with HLA-identical sibling donors and all patients with alternative family donors achieved trilineage engraftment. The median time intervals to reach peripheral neutrophil counts <500/microL (13 v 17 days) or <1,000/microL (16 v 19 days) and unsupported platelet counts <20,000/microL (11 v 15 days) or <50, 000/microL (19 v 24 days) as well as red blood cell and platelet transfusion requirements were not significantly different between both patient subsets. The cumulative probability of grades II through IV acute graft-versus-host disease (GVHD) for the 60 study patients was 48% +/- 10% but ranged between 86% +/- 12% in patients whose donors had at least one HLA-A,B,DR,DQ,DP antigen disparity in direction to acute GVHD, and 25% +/- 9% in recipients of GVHD-matched transplants (P < .003). The 2-year survival estimates were 54% +/- 10% for patients with alternative family donors and 65% +/- 9% for patients with HLA-identical sibling donors. Multivariate analysis identified the pretransplantation disease stage, patient age, and acute GVHD as independent predictors of overall and disease-free survival, whereas alternative family donors alone had no adverse effect on these clinical endpoints. Monthly monitoring of peripheral blood T-helper cell subsets, B cells, and monocytes during the first year posttransplantation showed a nearly identical course of immune cell reconstitution in both patient subsets. In addition, no differences in the proportions of complete chimeric patients were detectable between the two patient subsets by sex chromosome and variable number of tandem repeats analysis up to 12 months posttransplantation. In conclusion, PBSCs from alternative family donors represent an attractive source for allogeneic transplantation in patients lacking HLA-identical sibling donors and should be further evaluated in comparison with marrow transplants from alternative family donors.

Improved immune reconstitution after allotransplantation of peripheral blood stem cells instead of bone marrow.

Clinical studies are evaluating possible advantages of allogeneic peripheral blood stem cell transplantation (PBSCT) over bone marrow transplantation (BMT). We compared immune reconstitution after PBSCT (n = 20) and BMT (n = 20) in terms of lymphocyte subset counts and proliferative in vitro responses to mitogens and recall antigens (follow-up: 5 to 11 months posttransplant). Additionally, 10 PBSC harvests and 10 marrow harvests were analyzed for their composition of immunocompetent cells. Compared with BMT patients, PBSCT recipients had PB counts of naive (CD4+CD45RA+) and memory (CD4+CD45RO+) helper T cells and of B cells (CD19+) that were elevated (P < .003, P < .001, and P < .004, respectively) and proliferative responses to phytohemagglutinin (P < .0001), pokeweed mitogen (P < .02), Tetanus toxoid (P < .0005), and Candida (P < .004) that were increased. PBSCT recipients received a mean of 188 (range, 44 to 280) x 10(6) naive helper T cells and 169 (range, 18 to 296) x 10(5) memory helper T cells per kilogram; the corresponding numbers for BMT recipients were 11 (range, 4 to 24) and 10 (range, 1 to 22) x 10(5) cells per kilogram, respectively. The question of whether the documented improved in vitro immune competence after PBSCT is associated with a lower incidence of infectious complications in vivo still needs further study.