Chimerism analysis by lineage-specific fluorescent polymerase chain reaction in secondary graft failure after allogeneic stem cell transplantation

RETRACTED: The impact of second-donor lymphocyte infusion on secondary graft failure after allogeneic hematopoietic stem cell transplantation through activation of Foxp3 and regulatory T cells

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). The Editor of Cytotherapy has retracted this article. The article duplicates significant parts of a paper that had already appeared in Transplantation and Cellular Therapy, Volume 28, Issue 3, 2022, Pages 152.e1-152.e7, https://doi.org/10.1016/j.jtct.2021.12.017 In accordance with Committee on Publication Ethics (COPE) and Elsevier's policies, the authors have been contacted. After considering the author's response, the decision has been made to retract the paper. Redundant publications overweigh the relative importance of published findings and distort the academic record of the authors. One of the conditions of submission of a paper for publication is therefore that authors declare explicitly that the paper has not been previously published and is not under consideration for publication elsewhere. As such this article represents a misuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

Effect of donor lymphocyte infusion from two types of donors on Mixed Chimerism with Secondary Graft Failure after allogeneic haematopoietic stem cell transplantation

Mixed chimerism (MC) and secondary graft failure (SGF) with recipient-or donor-type chimerism is a major obstacle in allogeneic hematopoietic stem cell transpl- antation (HSCT). Donor lymphocyte infusion(DLI) can eradicate minimal residual disease or be used to rescue a hematologic relapse, being able to induce durable remissions after HSCT.This study aimed to analyse the efficacy and immune mecha- nism of DLI from the original and alternative donor for patients of mixed donor chimerism with SGF . The alternative donor refers to the candidate relative donor who did not initially provide stem cells include HLA-matched sibling donor(MSD) or HLA- haploidentical donor (HID). We conducted a retrospective study of 246 patients with a median age of 37 (9-58) years who were regularly detected MC, complete donor chimera (CC) and regulatory T cells (Treg). The median diagnosis time of SGF was 69 (39-141) days after transplantation . Sixteen patients of SGF received DLI from the alternative donor, including 3 patients who chose DLI from the original donor with no initial response and 13 patients who directly chose DLI from the alternative donor. Sixteen patients with SGF exsisted mixed chimerism synchronously and the rate calculated overall chimerism of MC was 63% (range, 42%-85%) after transplantation. The proportion of Treg decreased significantly in SGF patients from a median of (2.66% ±0.80%) to (0.93%±0.57%) at a time point after transplantation (p=0.02).The DLI of the alternative donor in 14 patients achieved complete response and MC gradually convert to CC state, simultaneously there was significant increase in the Treg fraction [SGF vs CR: (0.93% ± 0.57%) vs (3.61%±0.82%), p=0.01)].For the clinical nonres- ponders from two types of donor there was no significant change in MC and Treg cells. The OS and DFS at 2 years after DLI were 69.7%±3.19 % and 61.3%±4.80%, respectively. DLI from the alternative donor may be an effective treatment for MC with SGF and the mechanism is closely related to the activation of Treg cells level.

Quantitative analysis of chimerism using a short tandem repeat method on a fluorescent automated DNA sequencer

Stem cell transplantation (SCT) is the treatment of choice for a number of malignant and nonmalignant diseases. Monitoring of SC engraftment or microchimerism (MC) is important for diagnosis of relapse, rejection or graft vs. host disease (GVHD). The goal of this study was to develop a sensitive and relatively simple method for MC lineage analysis using the Visible Genetics fluorescence automated sequencer. Sensitivity of the method was studied by polymerase chain reaction (PCR) amplification of informative short tandem repeats (STR) using donor/recipient DNA mixtures as the templates and DNA extracted from donor and recipient CD3+, CD19+ and CD15+ cells mixed at various ratios. Semi-quantitative analysis was performed using the Visible Genetics software and percent of donor specific signal was calculated. The sensitivity of this method varied from 0.8% to 6.2% for both DNA and cellular MC in CD3+, CD19+ and CD15+ subsets. Regression analysis revealed linearity (r = 0.94) between the number of donor cells in the mixture and intensity of MC fluorescent signal. These data indicate that the Visible Genetics polyacrylamide gel sequencer can be successfully used for MC analysis in SC recipients providing a relatively high level of sensitivity.

Lineage-specific chimaerism after stem cell transplantation in children following reduced intensity conditioning: potential predictive value of NK cell chimaerism for late graft rejection

Chimaerism of FACS-sorted leucocyte subsets (CD14+, CD15+, CD3-/56+, CD3+/4+, CD3+/8+, CD19+) was monitored prospectively between days +14 and +100 in 39 children undergoing allogeneic stem cell transplantation with reduced intensity-conditioning regimens. Cell subsets exceeding 1% of nucleated cells were subject to cell sorting. Chimaerism was analysed by dual-colour FISH and/or by short tandem repeat-polymerase chain reaction. The chimaerism pattern on day +28 was evaluated with regard to its correlation with graft rejection. Of 39 patients, nine patients had donor chimaerism (DC) in all subsets. Mixed/recipient chimaerism (MC/RC) was detectable within T cells in 62%, within NK cells in 39% and within monocytes and granulocytes in 38% of the patients. The correlation of secondary graft rejection with the chimaerism pattern on day +28 revealed the strongest association between RC in NK-cells (P<0.0001), followed by T cells (P=0.001), and granulocytes and monocytes (P=0.034). Notably, patients with RC in T cells rejected their graft only if MC or RC was also present in the NK-cell subset. By contrast, none of the children with DC in NK cells experienced a graft rejection. These observations suggest that, in the presence of recipient T-cell chimaerism, the chimaerism status in NK-cells on day +28 might be able to identify patients at high risk for late graft rejection.

Serial quantification of lymphoid and myeloid mixed chimerism using multiplex PCR amplification of short tandem repeat-markers predicts graft rejection and relapse, respectively, after allogeneic transplantation of CD34+ selected cells from peripheral blood

We used multiplex amplification of nine microsatellite sequences (PCR-STR) to analyse chimerism in pure populations of T cells and neutrophils from peripheral blood from 40 patients submitted to an allogeneic transplant, 22 having received a T-cell depleted (TCD) peripheral blood graft by means of CD34(+) selection (allo-PBT/CD34(+)), and 18, an unmodified graft (allo-SCT; 13 allogeneic bone marrow transplants and five allo-PBT). T-cell mixed chimerism (TcMC) was observed in 16 of the 22 (72.3%) patients receiving an allo-PBT/CD34(+), but in only one of the 18 (5.5%) patients receiving an allo-SCT (P=0.0001). TcMC was transient (n=6), stable (n=7), and associated with poor haematopoietic engraftment (n=4). All patients with TcMC who developed graft failure had more than 30% of host T cells. Myeloid MC (MyMC) was observed in four (19%) allo-PBT/CD34(+) patients and in three (17%) allo-SCT patients (P=NS). Five out of seven (71%) patients with MyMC relapsed, all of them diagnosed with myeloid malignancies, as compared with two of the 20 (10%) patients with complete donor chimerism (P&<0.0001). In conclusion, TcMC appears in a significant number of allo-PBT/CD34(+) patients and may be associated with poor engraftment when the percentage of host T cells is >30%; likewise, MyMC appears in a small percentage of recipients of both allo-PBT/CD34(+) and allo-SCT patients, and is associated with leukaemia relapse in myeloid malignancies.

Quantitative assessment of hematopoietic chimerism after bone marrow transplantation by real-time quantitative polymerase chain reaction

We have developed a real-time quantitative polymerase chain reaction (PCR) assay using TaqMan technology (Applied Biosystems, Foster City, CA) for monitoring donor cell engraftment in allogenic hematopoietic stem cell transplant recipients. For this purpose, we selected 19 specific sequence polymorphisms belonging to 11 human biallelic loci located on 9 different chromosomes. Using a set of specially designed primers and fluorogenic probes, we evaluated the 19 markers' informativity on a panel of 126 DNA samples from 63 recipient/donor pairs. In more than 90% of these pairs, discrimination between recipient and donor genetic profile was possible. By using serial dilutions of mixed DNAs, we evaluated the linearity and sensitivity of the method. A linear correlation with r higher than 0.98 and a sensitivity of 0.1% proved reproducible. Fluorescent-based PCR of short tandem repeats (STR-PCR) and real-time PCR chimerism assay were compared with a panel of artificial cell mixtures. The main advantage of the real-time PCR method over STR-PCR chimerism assays is the absence of PCR competition and plateau biases, and results evidenced greater sensitivity and linearity with the real-time PCR method. Furthermore, different samples can be tested in the same PCR run with a final result in fewer than 48 hours. Finally, we prospectively analyzed patients who received allografts and present 4 different clinical situations that illustrate the informativity level of our method. In conclusion, this new assay provides an accurate quantitative assessment of mixed chimerism that can be useful in guiding early implementation of additional treatments in hematopoietic stem cell transplantation.

Autologous reconstitution combined with durable leukemic remission after allogeneic BMT for CML: absence of persistence of a donor-derived T cell effector population

We report a case of autologous hematopoietic recovery with durable leukemic remission after BMT from a phenotypically HLA-identical donor in a 30-year-old male with CML. Graft loss was diagnosed from day 60 post-BMT by VNTR PCR. To assess for the presence of a minor donor-derived T cell population that could exert an anti-leukemic effect, we serially applied a sensitive process of chimerism analysis by fluorescent PCR on sorted T cells. No residual donor T cells could be detected. We also showed retrospectively that a very sensitive method of MRD analysis by real-time quantitative PCR could have permitted prediction of relapse in this case.