Role of HLA in hematopoietic SCT

HLA disparity between hematopoietic stem cell (HSC) donor and recipient triggers T-cell and NK-cell allorecognition, and induces the GVHD, GVL effect and/or may cause an engraftment failure. This review will cover the scope of human genomic variation, the methods of HLA typing and interpretation of high-resolution HLA results. We describe the main subsets of related and unrelated HSC donors and outline the main aspects of HLA disparity and their effect on the outcome of the patients after allogeneic HSC transplantation (HSCT). The HLA match between HSCT donor and recipient is crucial, but for many patients a perfectly matched donor is not available. The HSCT from the alternative mismatched donor with one allele/antigen mismatch (9/10) can be as beneficial as a HSCT from a fully matched donor, especially in younger patients. For the remaining patients, the donors with permissive mismatches may be the option. The permissiveness depends not only on the potential adverse effect of the HLA mismatches, but also on the urgency of the transplantation, the desirable GVL effect and the potential efficacy of the alternative therapy available for the patient.     

Cellular therapy: exploiting NK cell alloreactivity in transplantation

Allogeneic hematopoietic transplantation relies on T-cell alloreactions for engraftment and the graft-versus-leukemia (GVL) effect. In human leukocyte antigen (HLA) haplotype-mismatched transplants, extensive T-cell depletion of the graft is essential to prevent GVHD. This raises the question of whether mismatched transplants exert any GVL effect and whether it will ever be possible to reduce the intensity of preparative regimens. Because natural killer (NK) cells are negatively regulated by MHC class I-specific inhibitory receptors, mismatched transplants may trigger NK-cell alloreactivity. HLA class I disparities driving NK-cell alloreactions in the GVH direction mediate strong GVL effects, produce higher engraftment rates, and do not cause GVHD. In murine MHC-mismatched transplant models with no donor T-cell reactivity against the recipient, the pre-transplant infusion of donor-vs-recipient alloreactive NK cells conditioned the recipients to bone marrow transplantation without GVHD. NK-cell alloreactivity may be a unique therapeutic tool for tolerance induction and clearance of leukemia in hematopoietic transplantation.     

Early emergence of PNH-like T cells after allogeneic stem cell transplants utilising CAMPATH-1H for T cell depletion

CAMPATH-1H (C-1H) is widely used in vivo and / or in vitro for T cell depletion in hematopoietic SCT. This humanised monoclonal antibody is specific for CD52, a marker coexpressed on the majority of human lymphocytes with CD48 and other glycosylphosphatidyl-inositol (GPI) anchored proteins. We detected CD52 / CD48 dual expression on >99% of CD3(+) lymphocytes from normal individuals and all 15 post-SCT patients whose transplants did not utilise C-1H. By contrast, 23 / 26 patients with transplants involving C-1H (in vivo, in vitro or both) exhibited populations lacking CD52 expression that accounted for 49.7% (4.2-86.2%) of the CD3+ lymphocytes (median and range) in samples evaluated at a median of 2 months post-SCT. Most CD52- cells also lacked CD48 expression. These GPI- T cells were of either donor or mixed donor / recipient origin. They were predominant in the early months after SCT at times of profound lymphopenia and inversely correlated with the recovery of the absolute lymphocyte count (r= - 0.663, P<0.0001). The presence of CD52- cells has been correlated previously with clinical outcome after CAMPATH therapy for both malignant and nonmalignant diseases.     

Immunohematological aspects of bone marrow transplantation

Allogeneic bone marrow transplantation (BMT) is an effective treatment for some severe hematologic or nonhematologic diseases. The blood group antigen mismatch between donor and recipient may cause immunohematological complications during or after BMT. In this review, we analyze the ABO, Rh and other red cell antigen mismatches between donor and recipient, the main immunohematological complications and the techniques to prevent them. The data reported are derived from the experience of the authors and from the medical literature. The clinical implications of the immunohematological aspects of BMT emphasize the importance of close immunohematological monitoring in patients undergoing allogeneic BMT with ABO, Rh or other red cell antigen mismatches between donor and recipient.     

Immunohematological Aspects of Bone Marrow Transplantation

Allogeneic bone marrow transplantation (BMT) is an effective treatment for some severe hematologic or nonhematologic diseases. The blood group antigen mismatch between donor and recipient may cause immunohematological complications during or after BMT.

In this review, we analyze the ABO, Rh and other red cell antigen mismatches between donor and recipient, the main immunohematological complications and the techniques to prevent them.

The data reported are derived from the experience of the authors and from the medical literature. The clinical implications of the immunohematological aspects of BMT emphasize the importance of close immunohematological monitoring in patients undergoing allogeneic BMT with ABO, Rh or other red cell antigen mismatches between donor and recipient.     

Transient engraftment of syngeneic bone marrow after conditioning with high-dose cyclophosphamide and thoracoabdominal irradiation in a patient with aplastic anemia

We describe the clinical course of a 16 year old girl with aplastic anemia who was treated by syngeneic bone marrow transplantation. Engraftment was not obtained by simple infusion of bone marrow without immunosuppression. The patient received a high-dose cyclophosphamide and thoracoabdominal irradiation, followed by second marrow transplantation from the same donor. Incomplete but significant hematologic recovery was observed; however, marrow failure recurred 5 months after transplantation. Since donor and recipient pairs were genotypically identical, graft failure could not be attributed to immunological reactivity of recipient cells to donor non-HLA antigens. This case report implies that graft failure in some cases of aplastic anemia might be mediated by inhibitory cells resistant to cyclophosphamide and irradiation.     

Natural killer cells expressing the KIR2DS1-activating receptor efficiently kill T-cell blasts and dendritic cells: implications in haploidentical HSCT

In allogeneic HSCT, NK-cell alloreactivity is determined by the presence in the donor of NK cells expressing inhibitory killer cell Ig-like receptors (KIRs) that recognize HLA class I allotypes present in the donor but lacking in the recipient. Dominant KIR ligands are the C1 and C2 epitopes of HLA-C. All HLA-C allotypes have either the C1 epitope, the ligand for KIR2DL2/L3, or the C2 epitope, the ligand for KIR2DL1/S1. Here, we show that, in alloreactive NK-cell responses, KIR2DS1 expression represents a remarkable advantage as it allows efficient killing of C2/C2 or C1/C2 myelomonocitic dendritic cells (DCs) and T-cell blasts. When DCs or T-cell blasts were derived from C2/C2, Bw4/Bw4 donors, the activating signals delivered by KIR2DS1 could override the inhibition generated by NKG2A or KIR2DL2/L3 expressed on the same NK-cell clone. Furthermore, substantial lysis of C2/C2, Bw4/Bw6 targets was mediated by KIR2DS1(+) NK cells coexpressing KIR3DL1. Importantly, in the case of C1/C2 targets, KIR2DS1(+) NK cells were inhibited by the coexpression of KIR2DL2/L3 but not of NKG2A. Thus, KIR2DS1 expression in HSC donors may substantially increase the size of the alloreactive NK-cell subset leading to an enhanced ability to limit GVHD and improve engrafment.     

NK-cell education is shaped by donor HLA genotype after unrelated allogeneic hematopoietic stem cell transplantation

The rules governing natural killer (NK)-cell education in the allogeneic environment created by unrelated hematopoietic stem-cell transplantation (HSCT) are still largely elusive, especially in an unrelated donor setting. NK-cell inhibitory receptors for self-human leukocyte antigen (HLA) play a central role in the acquisition or maintenance of NK-cell functional competence. Therefore, the responsiveness of different NK-cell subsets was assessed as a function of their expression or absence of expression of self-HLA-specific inhibitory receptors, in a large cohort (n = 60) of unrelated HSCT recipients. A fully effective NK-cell education process was achieved within the first year after allogeneic HSCT and lasted for at least 3 years thereafter. In addition, HLA-mismatched HSCT led to a stable education pattern that was determined by the donor's HLA ligands. These data suggest that the NK cell's education partner could be of hematopoietic rather than extrahematopoietic origin. This donor-ligand-driven NK-cell education model would suggest a sustained graft-versus-leukemia effect after HLA-mismatched HSCT.     

Engraftment kinetics after nonmyeloablative allogeneic peripheral blood stem cell transplantation: full donor T-cell chimerism precedes alloimmune responses.

Nonmyeloablative allogeneic stem cell transplantation has recently been explored as a safer alternative to conventional high-dose transplant regimens. Although a high incidence of mixed chimerism after nonmyeloablative procedures has been reported, the exact kinetics of engrafting donor cells in specific cellular lineages has yet to be defined. We investigated lineage-specific chimerism in 15 patients receiving an allogeneic peripheral blood stem cell (PBSC) transplant from an HLA-identical (n = 14) or a 5/6 antigen-matched sibling donor after a preparative regimen of cyclophosphamide and fludarabine. Donor chimerism was assessed weekly in T lymphocytes and myeloid cells by polymerase chain reaction (PCR) of minisatellite regions. Eight patients survived between 121 to 409 days after transplant. Ten of 14 patients surviving more than 30 days (71.4%) had delayed disease regression consistent with a graft-versus-malignancy (GVM) effect. One patient rejected the transplant with subsequent recovery of autologous hematopoiesis. Hematological recovery was rapid (median, 11 days to >/=500 neutrophils/microL) and was initially predominantly recipient in origin. Donor myeloid chimerism gradually supplanted recipient hematopoiesis and became fully donor in all survivors by 200 days after transplantation. In contrast, T-cell engraftment was more rapid, with full chimerism in 7 patients by day 30 and in 6 further patients by day 200 after cyclosporine withdrawal and donor lymphocyte infusion. Full donor T-cell engraftment preceded donor myeloid engraftment, acute graft-versus-host disease, and disease regression, consistent with a requirement for 100% donor T-cell chimerism for full expression of the alloresponse. These results emphasize the importance of lineage-specific chimerism analysis to successfully manipulate engraftment after nonmyeloablative allogeneic PBSC transplantation.     

Distribution of marrow repopulating cells between bone marrow and spleen early after transplantation

Whether hematopoietic stem cells (HSCs) home selectively to bone marrow (BM) early after transplantation remains an issue of debate. Better understanding of homing mechanisms may benefit BM transplantation protocols in cases of limited graft cell number or nonmyeloablative conditioning regimens. Using flow cytometry and serial transplantation to stringently identify HSCs, trafficking patterns of long-term engrafting cells were mapped between BM and spleen early after transplantation. Low-density BM cells were tracked in irradiated or nonirradiated mice 1, 3, 6, and 20 hours after transplantation, at which time recipient BM and spleen were analyzed for recovery of primitive donor cells by phenotype and adhesion molecule expression. In addition, phenotypically defined HSC-enriched or HSC-depleted grafts were tracked 20 hours after transplantation in recipient BM and spleen and analyzed for recovery and long-term repopulating potential in mice undergoing serial transplantation. Regardless of irradiation status, recovery of donor Sca-1+ lin- cells was higher at most time points in recipient BM than in spleen, while recovery of total Sca-1+ cells was variable. A significantly higher percentage of BM-homed donor Sca-1+ cells expressed CD43, CD49e, and CD49d 20 hours after transplantation than spleen-homed cells, which contained significantly more non-HSC phenotypes. Furthermore, BM-homed cells were significantly enriched for cells capable of secondary multilineage hematopoiesis in mice undergoing serial transplantation compared with spleen-homed cells. These results support the notion of specific homing of HSCs to BM by 20 hours after transplantation and provide a basis for the enhanced engraftment potential afforded some Sca-1+ lin- cells subfractionated on the basis of adhesion molecule expression.     

Anti-asialo GM1 antiserum treatment of lethally irradiated recipients before bone marrow transplantation: evidence that recipient natural killer depletion enhances survival, engraftment, and hematopoietic recovery

Natural killer (NK) cells are reported to have an important role in the resistance of lethally irradiated recipients to bone marrow transplantation (BMT). Therefore, we investigated the effects of recipient NK depletion on survival, chimerism, and hematopoietic reconstitution after lethal irradiation and the transplantation of limiting amounts of T-cell-deficient bone marrow (BM). When administered before BMT, anti-asialo GM1 (ASGM1) antiserum treatment, effective in depleting in vivo NK activity, was associated with a marked increase in survival in 3 of 3 allogeneic combinations (BALB/c into C3H/HeN, C57B1/6, or C3B6F1). This enhanced survival was independent of the susceptibility of each recipient strain to accept BALB/c BM. Moreover, recipient anti-ASGM1 treatment was also effective in increasing survival in recipients of syngeneic BM, suggesting that NK cells can adversely affect engraftment independent of genetically controlled polymorphic cell surface determinants. Analysis of chimerism in surviving animals 2 months post-BMT showed that recipient NK depletion significantly increased the level of donor engraftment when high doses of BM were transplanted. These studies also demonstrated that anti-ASGM1 pretreatment mainly resulted in an increase in extramedullary hematopoiesis in the second and third week after irradiation. Anti-ASGM1 treatment also dramatically accelerated the rate of appearance of donor-derived cells with a higher level of donor-cell engraftment apparent at a time when the differences in survival between NK-depleted and control BMT recipients became significant. Peripheral cell counts were also affected by NK depletion, with significantly enhanced platelet and red blood cell recovery and a moderate increase in granulocyte recovery. The overall favorable influence of anti-ASGM1 recipient treatment on hematopoietic events post-BMT suggests that, in humans, pretransplant regimens aimed toward NK depletion should be evaluated.     

Successful adoptive transfer and in vivo expansion of human haploidentical NK cells in patients with cancer

We previously demonstrated that autologous natural killer (NK)-cell therapy after hematopoietic cell transplantation (HCT) is safe but does not provide an antitumor effect. We hypothesize that this is due to a lack of NK-cell inhibitory receptor mismatching with autologous tumor cells, which may be overcome by allogeneic NK-cell infusions. Here, we test haploidentical, related-donor NK-cell infusions in a nontransplantation setting to determine safety and in vivo NK-cell expansion. Two lower intensity outpatient immune suppressive regimens were tested: (1) low-dose cyclophosphamide and methylprednisolone and (2) fludarabine. A higher intensity inpatient regimen of high-dose cyclophosphamide and fludarabine (Hi-Cy/Flu) was tested in patients with poor-prognosis acute myeloid leukemia (AML). All patients received subcutaneous interleukin 2 (IL-2) after infusions. Patients who received lower intensity regimens showed transient persistence but no in vivo expansion of donor cells. In contrast, infusions after the more intense Hi-Cy/Flu resulted in a marked rise in endogenous IL-15, expansion of donor NK cells, and induction of complete hematologic remission in 5 of 19 poor-prognosis patients with AML. These findings suggest that haploidentical NK cells can persist and expand in vivo and may have a role in the treatment of selected malignancies used alone or as an adjunct to HCT.     

Constitutional pericentric inversion of chromosome 9 and hematopoietic recovery after allogeneic stem cell transplantation

Recent reports suggest that hemopoietic stem cells with constitutional pericentric inversion of chromosome 9 [inv(9)] may be related to delayed engraftment or hemopoietic defect after stem cell transplantation (SCT). We conducted a retrospective study on five allogeneic SCT in which constitutional inv(9) was detected either in the donor or the recipient. The results showed that hematologic recovery was within the expected time range for all our patients. However, one patient exhibited decreasing blood counts between day +45 and +272 after transplantation, possibly due to protracted cytomegalovirus (CMV) infection and gansiclovir and imatinib treatment. Our findings suggest that constitutional inv(9) may not be associated with delayed hemopoietic recovery after SCT.     

Living donor liver transplants: potential disadvantages

Abstract   Living donor liver transplants (LDLTs) have provided many patients with a lifesaving option. Yet this option remains a significant undertaking, with potentially serious consequences for both the donor and the recipient. The donor is obviously the individual with the most to lose. The exact risks to the donor are difficult to quantify because reporting adverse donor events is not mandatory and no registry exists. The risk to the donor also depends on the extent of the donor resection. By some estimates, the risk of donor mortality is 0.3% to 1.0%. The reported risk of donor complications varies greatly in the literature—ranging from 5 to 60%. Reported complications are usually short-term complications, since most donors are not followed by the transplant center after the first year. Very few studies have examined other issues that are important for the donor, such as the quality of life after donation, the time to full recovery, and the financial impact of donation. For the recipient, an LDLT is a lifesaving procedure. Especially in countries where deceased donation is scarce, the benefits of an LDLT for the recipient are obvious. However, analysis of national data from the United States demonstrates that, at least for adults, results of an LDLT may be inferior, as compared with a whole-liver transplant from a deceased donor. Moreover, the surgical complication rate after an LDLT is significantly higher. As LDLTs continue to gain in popularity, careful evaluation and re-evaluation of both donor and recipient outcomes are necessary to optimize results.     

The reconstitution of CD45RBhiCD4+ naive T cells is inversely correlated with donor age in murine allogeneic haematopoietic stem cell transplantation

A high incidence of opportunistic infections after unrelated bone marrow transplantation has been reported. Delayed lymphocyte recovery may be associated with opportunistic infections. Immune reconstitution is influenced by recipient age and graft-vs-host disease (GVHD). In fact, children develop GVHD less frequently than adults. However, the role of donor age is largely unknown. We examined the effect of donor age on lymphocyte reconstitution after transplant. Three-month-old BALB/c recipient mice were lethally irradiated and transplanted with allogeneic haematopoietic stem cells from A/J donor mice of different ages, ranging from 0 d to 12 months. The recovery of absolute lymphocyte counts and those of CD3+ T cells, CD4+ T cells and CD45RBhi CD4+ naive T cells in the early post-transplant period correlated inversely with donor age. Recipient mice transplanted with haematopoietic stem cells from younger donors showed significantly higher survival rates and mitogenic responses than adult donors. As T cells, especially CD4+ naive T cells, play an important role in host defence, faster recovery of CD4+ naive T cells in younger donors may contribute to reduced mortality in the early post-transplant period. The results suggest that it could be better to choose a younger donor if sufficient cell dose is available.     

Living donor hepatectomy in a pregnant woman

Liver transplantation with a live donor is an effective way to expand the donor pool. Restrictive selection of living donors may assure donor safety but limit the utility of this resource. A 12-month-old recipient with biliary atresia was rapidly deteriorating with hepatic encephalopathy, massive ascites and coagulopathy. Her mother, the only possible living donor, expressed a strong desire to donate part of liver to her baby, although she was found to be pregnant. The donor hepatectomy was then undertaken at 18 weeks of gestation. A left lateral segmentectomy was performed. Her postoperative course was uneventful and she was discharged 7 days after the operation. She gave birth to a healthy term baby without any complications 5 months later. Both recipient and her younger brother are well 12 months after the operation. Despite the limited experience reported herein, pregnancy may no longer be considered an absolute contraindication for live liver donation.     

Patients' psychosocial concerns following stem cell transplantation

Information regarding the nature, frequency, correlates and temporal trajectory of concerns of stem cell transplantation (SCT) recipients is critical to the development of interventions to enhance quality of life (QOL) in these individuals. This study examined psychosocial concerns in 110 SCT (87% autologous) recipients drawn from two SCT centers. Participants were a mean of 46 years of age and 17 months post-SCT (range 3-62 months). Information regarding current and past SCT-related concerns, performance status, and demographic characteristics was collected by telephone interview or questionnaire. Recipients reported a wide variety of psychosocial concerns following SCT. Recipients who were younger, female and evidenced a poorer performance status reported a larger number of post-SCT concerns. Examination of the temporal trajectory of concerns suggests that some concerns are salient throughout the course of post-SCT recovery (eg disease recurrence, energy level, 'returning to normal'), some are salient early in the course of recovery (eg quality of medical care, overprotectiveness by others), and others emerge later in the course of recovery (eg feeling tense or anxious, sexual life, sleep, relationship with spouse/partner, ability to be affectionate). Implications for the development of interventions to enhance post-SCT QOL are identified.     

Transfer and persistence of viral antibody-producing cells in bone marrow transplantation

Antiviral humoral reactivity was studied after bone marrow transplantation. Antiviral IgG--reflecting the presence of functional B cells--was found for a substantial period after transplantation. However, most patients unexpectedly stopped producing antibody after an extended period of observation (i.e., for more than three months and up to as long as 12 months). This cessation was noted whether the viral reactivity involved was of donor or recipient origin. The transferred viral antibody-producing cells thus usually persisted for only a moderate length of time and seemed to have a finite life span. The findings indicate that donor and recipient memory cells are susceptible to the conditioning regimen or to the treatment that follows transplantation. In a few cases transferred immunity of long duration was seen; this finding indicated the occasional engraftment of memory cells.     

Interrelation between donor and recipient heart rates during exercise after heterotopic cardiac transplantation.

The interrelation between the rates of the innervated recipient heart and the denervated donor heart at rest, on standing, and during the different phases of maximal exercise was studied in nine patients 1-6 months after heterotopic cardiac transplantation. The resting heart rate was significantly higher in the donor heart compared with the recipient heart. Eight of the nine recipient hearts and none of the donor hearts showed an increase in heart rate on standing up. All patients were exercised using a Bruce protocol until fatigued. The increase in heart rate during the first three minutes of exercise was lower in the donor hearts (10.7(6) beats/min) than in the recipient hearts (30(4.8) beats/min) but the peak heart rates were almost identical (donor hearts 152.7(2.9) and recipient hearts 152(2.8) beats/min). Five of the nine donor hearts and none of the recipient hearts showed a significant increase in heart rate after cessation of exercise. Three minutes after exercise heart rate had decreased by only 0.2(5.7) beats/min in the donor hearts compared with 33.6(6) beats/min in the recipient hearts. In spite of these differences in response between the donor hearts and recipient hearts, there were significant correlations between the two heart rates in the same patient at rest, after the first three minutes of exercise, at peak exercise, and during recovery.     

Interrelation between donor and recipient heart rates during exercise after heterotopic cardiac transplantation

The interrelation between the rates of the innervated recipient heart and the denervated donor heart at rest, on standing, and during the different phases of maximal exercise was studied in nine patients 1-6 months after heterotopic cardiac transplantation. The resting heart rate was significantly higher in the donor heart compared with the recipient heart. Eight of the nine recipient hearts and none of the donor hearts showed an increase in heart rate on standing up. All patients were exercised using a Bruce protocol until fatigued. The increase in heart rate during the first three minutes of exercise was lower in the donor hearts (10.7(6) beats/min) than in the recipient hearts (30(4.8) beats/min) but the peak heart rates were almost identical (donor hearts 152.7(2.9) and recipient hearts 152(2.8) beats/min). Five of the nine donor hearts and none of the recipient hearts showed a significant increase in heart rate after cessation of exercise. Three minutes after exercise heart rate had decreased by only 0.2(5.7) beats/min in the donor hearts compared with 33.6(6) beats/min in the recipient hearts. In spite of these differences in response between the donor hearts and recipient hearts, there were significant correlations between the two heart rates in the same patient at rest, after the first three minutes of exercise, at peak exercise, and during recovery.