Adoptive immunotherapy against kidney targets in dog-leukocyte antigen-identical mixed hematopoietic canine chimeras.

BACKGROUND: Stable mixed-donor-host-hematopoietic chimerism can serve as a platform for adoptive immunotherapy. Infusions of donor lymphocytes (DLI) sensitized against hematopoietic cells converted mixed hematopoietic into full-donor chimerism in dog-leukocyte antigen (DLA)-identical littermates. Whether sensitization against tissue of solid organs leads to organ-specific immunity that can be transferred by DLI was unknown and was investigated in these experiments using the kidney as target. METHODS: DLA-identical recipients with established stable mixed-donor-host-hematopoietic chimerism were used. In five pairs, hematopoietic stem-cell transplant (HSCT) donors were sensitized by kidney transplantation from the respective chimeras. In a second group, five HSCT donors received vaccinations that were generated from kidney cells of the respective mixed chimeras. Twenty-eight days after sensitization, DLI were administered to the mixed-hematopoietic chimeras. RESULTS: All HSCT donors rejected their kidney grafts from their mixed-chimeric recipients within 22 to 45 days. DLI caused no sustained graft-versus-kidney effects in the mixed-chimeric recipients. However, DLI donors sensitized by kidney transplantation converted 4 of 5 mixed chimeras into virtually complete (>95%) donor-type chimeras, compared with 1 of 5 mixed chimeras given DLI by vaccination from sensitized donors. CONCLUSION: Although DLA-identical kidney grafts from mixed-hematopoietic chimeras were readily rejected by their HSCT donors, subsequent transfusions of sensitized-donor lymphocytes into mixed chimeras converted mixed to all-donor chimerism but failed to induce graft-versus-kidney effects. Vaccination strategies in lieu of kidney grafts failed to convert mixed chimerism.

Adoptive immunotherapy to increase the level of donor hematopoietic chimerism after nonmyeloablative marrow transplantation for severe canine hereditary hemolytic anemia.

Severe hemolytic anemia in Basenji dogs secondary to pyruvate kinase deficiency can be corrected by allogeneic hematopoietic cell transplantation (HCT) from littermates with normal hematopoiesis after conventional myeloablative or nonmyeloablative conditioning regimens. If the levels of donor chimerism were low (<20%) after nonmyeloablative HCT, there was only partial correction of the hemolytic anemia. We next addressed whether allogeneic cell therapy after nonmyeloablative HCT would convert mixed to full hematopoietic chimerism, achieve sustained remission from hemolysis, and prevent progression of marrow fibrosis and liver cirrhosis. Three pyruvate kinase-deficient dogs were given HCT from their respective dog leukocyte antigen-identical littermates after nonmyeloablative conditioning with 200 cGy of total body irradiation. Postgrafting immunosuppression consisted of mycophenolate mofetil and cyclosporine. All 3 dogs engrafted and had mixed hematopoietic chimerism with donor levels ranging from 12% to 55% in bone marrow. In 2 of the 3 dogs, there were decreases in the levels of donor chimerism so that at 25 weeks after nonmyeloablative HCT, hemolysis recurred that was associated with increased reticulocyte counts. All 3 dogs then had 2 serial infusions of donor lymphocytes (DLI) from their respective donors at least 20 weeks apart to convert from mixed to full donor chimerism. Both dogs with recurrence of hemolytic anemia after nonmyeloablative HCT achieved higher levels of donor chimerism, with donor contributions ranging from 47% to 62% in the bone marrow and 50% to 69% and 16% to 25% in the granulocyte and mononuclear cell fractions of the peripheral blood, respectively, and with remission of the hemolytic anemia. One dog responded after the first DLI, and 5 weeks after the second DLI, the other dog converted to full donor chimerism. At last follow-up, all these dogs showed clinical improvement, as determined by increasing hematocrits and normal reticulocyte counts. Analysis of the marrow 3 years after HCT showed normal cellularity, a normal myeloid-erythroid ratio, and no or minimal marrow fibrosis. Liver biopsies demonstrated normal histologies with no or minimal fibrosis. We conclude that DLI after nonmyeloablative HCT can increase the levels of donor cells contributing to hematopoiesis in recipients, inducing remissions of the hemolytic process and preventing complications associated with iron overload.

Effect of c-mpl ligands after total body irradiation (TBI) with and without allogeneic hematopoietic stem cell transplantation: low-dose TBI does not prevent sensitization.

This study investigates the potential role of the recombinant c-mpl ligands (recombinant human thrombopoietin [rhTPO] and pegylated recombinant human megakaryocyte growth and development factor [PEG-rhMGDF]) on the recovery of platelet counts after TBI with and without allogeneic hematopoietic stem cell transplantation (HSCT) in an established canine model. Initially, 3 cohorts, each with 2 nonirradiated dogs, received increasing doses of rhTPO (5 microg/kg per day; 10 microg/kg per day; 20 microg/kg per day) for 7 days to determine the optimal dose. The dose of 10 microg/kg per day of rhTPO was selected for subsequent studies. Ten dogs then received either rhTPO or placebo for 28 days after 200 cGy TBI without HSCT. The rhTPO group had fewer days with platelet counts <20,000/microL (9.8 days versus 17.8 days, P < .05) and significantly increased granulocyte counts (n = 5) compared to the controls (n = 5). RhTPO-specific antibodies developed in 2 dogs, which caused a significant but transient decrease of the platelet counts. Retreatment of these sensitized dogs with rhTPO resulted in profound transient decreases in platelet counts. In the next study, 20 dogs received either PEG-rhMGDF or placebo for 21 days after 920 cGy TBI and allogeneic HSCT. The median time to platelet recovery (>20,000/microL) for the PEG-rhMGDF group (n = 10) was 14.0 days compared to 15.5 days for the control group (n = 10; log rank, P = .35). There were no significant differences in the total time to platelet counts <20,000/microL or in the time to recover neutrophil counts >500/microL. The effects of rhTPO on recovery of platelet and granulocyte counts after sublethal TBI were modest, and no effects of PEG-rhMGDF were observed on hematopoietic recovery after high-dose TBI and allogeneic HSCT. The significant effect that rhTPO-specific antibodies had on the platelet counts may limit the clinical role of recombinant c-mpl ligands unless sensitization can be prevented.

Engraftment of early erythroid progenitors is not delayed after non-myeloablative major ABO-incompatible haematopoietic stem cell transplantation.

We hypothesized that patients undergoing major ABO-incompatible non-myeloablative haematopoietic stem cell transplantation (nm-HSCT) might experience prolonged haemolysis after transplant due to the delayed disappearance of host plasma cells producing anti-donor isohaemagglutinins (HAs). To address this question, we analysed data from 107 consecutive patients transplanted with allogeneic peripheral blood stem cells from human leucocyte antigen-matched (related, n = 84; unrelated, n = 23) donors after non-myeloablative conditioning (200 cGy total body irradiation +/- fludarabine). In total, 23 out of the 107 patients received major or major/minor ABO-incompatible transplants. Red blood cell (RBC) transfusion requirements during the first 120 d post transplant were higher in major ABO-mismatched than in ABO-matched recipients (0.12 vs 0.03 median units RBC concentrate/d, P = 0.04). Two patients developed transient pure red cell aplasia, which had resolved spontaneously by 9 months after transplant. Major ABO incompatibility did not influence rates of engraftment. Patients with sustained engraftment experienced gradual declines of anti-donor HAs, and the estimated median time to reaching IgM and IgG titres of < 1:1 was at least 133 d in evaluable patients, approximately twice longer than reported after myeloablative conditioning. There was a strong correlation between degrees of donor chimaerism in erythroid burst-forming units, granulocyte macrophage colony-forming units and granulocytes, indicating that donor erythroid engraftment, defined by early erythroid progenitors, was as prompt as myeloid engraftment. In conclusion, our data suggest that major ABO-incompatibility is not a barrier to successful non-myeloablative HSCT.

Performance of a new clinical grading system for chronic graft-versus-host disease: a multicenter study.

We recently reported 3 risk factors (RFs) at diagnosis of chronic graft-versus-host disease (cGVHD) that were significantly associated with increased nonrelapse mortality. These included extensive skin involvement (ESI), thrombocytopenia (TP), and progressive type of onset (PTO). The hazard ratio (HR) for mortality of the patients with prognostic score (PS) between 0 and 2 (intermediate-risk; 1 RF) compared to those with PS 0 (favorable-risk; 0 RF) was 3.7 (95% CI, 1.4, 9.3); the HR for patients with PS equal to or more than 2 (high-risk; > 1 RF) compared with intermediate-risk group was 6.9 (3.8, 12.4). A rare presentation of TP and PTO without ESI yielded a PS of 1.8 (intermediate-risk). This paper reports the performance of the prognostic model and the individual RFs using data from an additional 1105 patients from University of Nebraska (n = 60), International Bone Marrow Transplantation Registry (n = 708), Fred Hutchinson Cancer Research Center (n = 188), and University of Minnesota (n = 149). The extent of skin involvement was quantified in 3 cohorts using the available data collected in different formats before the analysis. Although the HR for mortality of the patients in the intermediate-risk group versus those in the favorable-risk group ranged from 2.3 to 8.9 across the centers, it was between 1.6 to 6.9 for patients in the high-risk group versus those in the intermediate-risk group. Although TP itself was uniformly associated with increased risk of mortality across all test samples, ESI and PTO showed statistically significant associations with mortality in 1 and 2 cohorts, respectively. In conclusion, the model was predictive of cGVHD-specific survival, but the mortality hazard associated with ESI was lower in each of these test samples compared with the learning sample. Although the new clinical grading based on the model is promising because of its utility across multiple independent data sets, prospective validation is needed.

Toxoplasmose cerebral após transplante alogênico de medula óssea / Central nervous system toxoplasmosis after bone marrow transplantation

As cpmplicaçöes relacionadas ao sistema nervoso central nos pacientes submetidos a transplante autólogo ou alogênico de medula óssea apresentam uma incidência média de 2 a 8 por cento, que correlacionam com o grau de imunossupressäo, doença enxerto contra o hospedeiro e a doença de base. Por este motivo observa-se maior incidência dessas complicaçöes nos tranplantes alogênicos. Dentre as mais comumentes encontradas, destacam-se as de causas infecciosas, como encefalites secundárias, o toxoplasma, aspergilus, cândida, citomegalovírus e outros vírus. Excluindo-se as infecçöes, destacam-se as hemorragias e a encefalopatia metabólica. Apesar da incidência de 3 a 8 por cento, a mortalidade dos pacientes acometidos atinge 67 por cento dos casos. Por este motivo é que torna-se importante a avaliaçäo sorológica dos pacientes previamente ao transplante e a investigaçäo dos agentes etiológicos em pacientes imunocomprometidos, após o transplante de medula óssea.