Graft-versus-host-disease-associated lymphoid hypoplasia and B cell dysfunction is dependent upon donor T cell-mediated Fas-ligand function, but not perforin function

Allogeneic bone marrow transplant recipients often exhibit a graft-versus-host-disease (GVHD)-associated immune deficiency that can be prolonged and lead to life-threatening infections. We have examined the role of donor T cell-mediated cytotoxic function in the development of GVHD-associated immune deficiency. A major histocompatibility complex-matched model of allogeneic bone marrow transplantation was employed in which lethally irradiated C3H.SW mice received a nonlethal dose of T cells from either perforin-deficient (B6-perforin 0/0), Fas-ligand (FasL)-defective (B6-gld), or normal (B6) allogeneic donor mice. T cell-depleted marrow from B6-Ly-5.1 congenic donor mice was transplanted along with the donor T cell populations to determine the effects of donor T cell-mediated cytotoxicity on engraftment. Our results demonstrate that recipients of perforin-deficient or normal allogeneic T cells exhibit profound lymphoid hypoplasia and severely reduced splenic proliferative responses to lipopolysaccharide in vitro. In contrast, GVHD-associated lymphoid hypoplasia is dramatically reduced and in vitro B cell function is intact in recipients of FasL-defective allogeneic T cells. Engraftment of myeloid and erythroid lineage cells occurs irrespective of donor T cell cytotoxic function. Although recipients of perforin-deficient or normal allogeneic T cells exhibited hematopoietic engraftment exclusively of donor origin, recipients of FasL-defective donor T cells exhibited significant mixed chimerism (Ly-5.1/Ly-5.2). Because only marrow of donor origin was transplanted, this finding suggests that Fas-mediated antirecipient cytotoxicity is required for clearance of residual hematopoietic stem cells of host origin that persist following lethal irradiation.     

Characterization of SCML1, a new gene in Xp22, with homology to developmental polycomb genes

BACKGROUND: Mixed hematopoietic chimerism induced with a nonmyeloablative conditioning regimen leads to donor-specific transplantation tolerance. Analyses of specific Vbeta-bearing T-cell families that recognize endogenous superantigens demonstrated that donor-specific tolerance is due mainly to an intrathymic deletional mechanism in these mixed chimeras. However, superantigens are not known to behave as classical transplantation antigens. We therefore used T-cell receptor (TCR) transgenic (Tg) recipients expressing a clonotypic TCR specific for an allogeneic major histocompatibility complex antigen to further assess deletional tolerance. METHODS: 2C TCR Tg mice (H2b), whose Tg TCR recognizes major histocompatibility complex class I Ld, were used as recipients of Ld+ bone marrow cells after conditioning with depleting anti-CD4 and CD8 monoclonal antibodies, 3 Gy whole-body irradiation, and 7 Gy thymic irradiation. Chimerism and deletion of CD8+ 2C recipient T cells was evaluated by flow cytometry and by immunohistochemical staining. Tolerance was tested with in vitro cell-mediated lympholysis assays and in vivo by grafting with donor skin. RESULTS: Intrathymic and peripheral deletion of 2C+ CD8-single-positive T cells was evident in mixed chimeras, and deletion correlated with the presence of donor-type cells with dendritic morphology in the thymus, and with chimerism in lymphohematopoietic tissues. Chimeras showed tolerance to the donor in cell-mediated lympholysis assays and specifically accepted donor skin grafts. CONCLUSIONS: Tolerance to transplantation antigens is achieved through intrathymic deletion of donor-reactive T cells in mixed chimeras prepared with a nonmyeloablative conditioning regimen and allogeneic bone marrow transplantation.     

Chimerism analysis in long-term survivor patients after bone marrow transplantation for severe aplastic anemia

BACKGROUND AND OBJECTIVE: Allogeneic bone marrow transplantation (BMT) is the most common treatment for young patients with severe aplastic anemia (SAA). Late graft failure represents one of the possible unfavorable outcomes in this setting. Mixed chimerism might represent a risk factor for late graft failure. We examined this relationship by studying chimerism in long-term survivor SAA patients after allogeneic BMT. METHODS: We analyzed long-term hematopoietic chimerism in 15 patients who received BMTs for SAA: 9 with an irradiation-based conditioning regimen and 6 with ATG. We used a PCR method targeting VNTR loci. Sensitivity of the technique ranged between 0.5 and 1.5%. RESULTS: All patients conditioned with radiation-based schemes showed complete donor chimerism. Conversely, out of six patients who received cyclophosphamide and ATG as a conditioning regimen, only one of them had late graft failure (day +168). In this patient, durable mixed chimera status was first detected two months after BMT. INTERPRETATION AND CONCLUSIONS: Our results suggest that in long-term survivors of SAA after BMT there is almost always complete donor chimerism in both irradiated and ATG-conditioned recipients. Mixed chimerism might predict graft failure in these patients.     

Stable mixed chimerism without relapse after related allogeneic umbilical cord blood transplantation in a child with severe aplastic anemia

Umbilical cord blood (UCB) cells from HLA-matched donors are used as an alternative to bone marrow for allogeneic transplantation and reports of successful UCB transplantation in patients with severe aplastic anemia (SAA) are scarce. SAA was discovered in a 4-year-old girl in February 1990. Transfusion support started in August 1990 and standard treatments were unsuccessful. The birth of an HLA-compatible brother in October 1993 permitted the cryopreservation of UCB. In December 1994 UCB transplantation was decided upon. No toxicity occurred. G-CSF was started at day 28. WBC and PMN reached 0.5 x 10(9)/l at days 33 and 37. RBC and platelet transfusion independence were reached at days 50 and 52. Mixed chimerism was demonstrated in blood cells at 1.5, 4 and 6 months after UCBT by molecular biology (VNTR). FISH studies yielded similar results at 15 and 18 months. Twenty months after UCBT, molecular biology showed full donor chimerism. Clinical follow-up (last follow-up: 32 months post transplant) is unremarkable. We suggest that CY and ATG may be a suitable regimen for related HLA-compatible UCBT in patients with SAA. Residual recipient cells can disappear even very late after UCBT, permitting the establishment of complete donor chimerism.     

Pretransplant injection of allograft recipients with donor blood or lymphocytes permits allograft tolerance without the presence of persistent donor microchimerism

Donor-recipient microchimerism has recently been suggested to play a critical role in the induction and maintenance of allograft tolerance. In this study we sought evidence for this hypothesis using the LEW-to-ACI cardiac allograft as a model system. Donor-specific tolerance to cardiac allografts was induced by intravenous or intraportal injection of graft recipients with donor peripheral blood, T cells, or B cells 7 days before transplantation. All the graft recipients injected with donor antigens accepted donor heart grafts indefinitely when compared with control recipients that rejected donor allografts in 12 days. Long-term graft survivors rejected third-party BN heart allografts in 14 days without an adverse effect on the survival of the first LEW heart allografts, demonstrating the specificity of the tolerance. Tissue lysates prepared from heart, kidney, liver, bone marrow, thymus, lymph nodes, and spleen of tolerant (>120 days) graft recipients were analyzed for the presence of donor DNA using LEW T cell receptor C beta gene-specific primers for polymerase chain reaction that detects donor DNA at > or = 1:10,000 dilution. Donor DNA was detected in 77% of tolerant graft recipients. Chimeric recipients showed variations in the levels and presence of donor DNA in different tissues. The status of donor microchimerism, with respect to its presence and tissue distribution, was dependent upon the donor cell type and route of injection used for the induction of tolerance. Intraportal injection of the graft recipients with donor peripheral blood resulted in the highest degree of chimerism, whereas intravenous injection with donor B cells did not induce detectable microchimerism in this group of recipients. These data clearly demonstrate that the presence of microchimerism is common following administration of donor cells, but that its presence is not an absolute requirement for the long-term survival of allografts.     

Proliferative activity and loss of function of tumour suppressor genes as ''biomarkers'' in diagnosis and prognosis of benign and preneoplastic oral lesions and oral squamous cell carcinoma

Patients with hematologic malignancy or severe aplastic anemia after myeloablative chemo- and radiotherapy were given granulocyte colony-stimulating factor (G-CSF)-mobilized, cryopreserved allogeneic peripheral blood stem cells (PBSCs) from 15 healthy donors who were either human leukocyte antigen (HLA)-matched siblings (n = 13) or haploidentical offspring (2). Polymerase chain reaction-amplified short tandem repeat genotyping was used for early confirmation of donor engraftment after PBSC transplantation (PBSCT). A standard cyclosporine A/methotrexate combination was used to prevent acute graft-versus-host disease (GVHD). All donors, including one in the third trimester of pregnancy, tolerated G-CSF administration and 3-day PBSC harvesting procedures well. Engraftment was prompt for all patients; it was verified using a panel of 12 human polymorphic short tandem repeat loci from bone marrow as early as 7 days posttransplantation. This status was maintained until relapse, when mixed chimerism was detected using the polymerase chain reaction. A minimum resurgence of recipient cells to 1% of the population was required to detect chimerism. The median times to recovery of the absolute neutrophil count to greater than 0.5 x 10(9)/L and the sustained platelet count to greater than 20 x 10(9)/L without transfusion were 10 and 12 days after PBSCT, respectively. Six patients experienced acute GVHD, Grade I in two patients and Grade II in four, including two HLA-haploidentical recipients. Chronic GVHD was noticed in three of the 11 patients who were followed for at least 100 days after PBSCT. Ten patients were still alive at the latest follow-up and have been disease free for a median of 278 days (range 60-671). Five patients died from causes other than graft failure: three from leukemia relapse and two from transplant-related complications. The results confirm that G-CSF can be safely administered to healthy donors and that engraftment after allogeneic PBSCT is fast and durable. Complete chimerism can be detected early by genomic analysis. PBSCT may offer an alternative to bone marrow transplantation.     

Long-term engraftment following in utero T cell-depleted parental marrow transplantation into fetal rhesus monkeys

A major concern with allogeneic BMT for treating most inherited diseases is the need to overcome graft rejection with conditioning chemotherapy which is associated with a relatively high morbidity and mortality. This can be eliminated if the transplant is done in utero when the fetus is unable to reject donor hematopoietic stem cells (HSC). We studied the efficacy of T cell-depleted (TCD) parental bone marrow as a source of HSC for transplantation into early gestation non-defective fetal rhesus monkeys. Thirteen opposite sexed TCD transplants were done into 44 day fetal recipients and 12 into 61 day recipients (165 day total gestation). The procedure-related mortality was 8%, all in the earlier age group. The overall survival was 60% at birth with a projected survival of 44 +/- 10% at 1.5 years with no difference between the two age groups. We used a PCR assay for the rhesus Y chromosome to detect male donor cells in female recipients (six animals transplanted at 44 days and five at 63 days). The overall engraftment rate was 73% with no difference as a function of gestational age at transplant. In six long-term surviving engrafted females we detected donor cells in the peripheral blood and bone marrow up to 3 years of age. We found a delay in the appearance of donor cells in the peripheral blood in engrafted animals, in some cases for up to 6 months post-BMT. In vitro mixed lymphocyte reaction and cell-mediated lymphocytotoxicity studies between the recipient and donor cells indicate that tolerance was induced to donor cells. Individual and pooled erythroid and myeloid marrow colonies grown in methyl cellulose were collected and analyzed for donor origin by PCR. The amount of donor cells in marrows from long-term engrafted animals was < 0.1%. In a fetal recipient studied at 35 days post-BMT, donor cells were detected in bone marrow and liver in both erythroid and myeloid lineages. These results indicate that TCD parental marrow can durably engraft in utero. While the engraftment rate is similar to that seen with fetal liver as the source of HSC, the degree of peripheral blood engraftment (percent donor cells) in this non-defective primate model is low. It will require increasing the percent pre-or postnatally for this approach to be clinically relevant in those disorders in which there is no selective survival advantage for normal engrafted donor cells.     

Autologous stem cell transplantation. From bone marrow to selected blood stem cells: 100 consecutive procedures at a single center

One hundred consecutive autologous stem cell transplants are reported: Non-Hodgkin's lymphoma 51 cases, Hodgkin's disease 27 cases, acute leukaemia 14 cases, multiple myeloma seven cases and chronic myeloid leukaemia one case. Most patients were in their second or later remission. The overall three-year survival for all patients was 60% and the three-year disease-free survival was 50% for lymphoma patients and 30% for acute leukaemia patients. The dominant source of stem cells was bone marrow during 1993, but from 1994 it has been peripheral blood, now totalling 33 cases. There were 12 toxic deaths, all among patients who were heavily treated before bone marrow harvest and transplantation. The patients transplanted with blood stem cells had significantly shorter duration of pancytopenia, and hospital stay, but their disease-free survival was not longer than that of a comparable group of bone marrow transplanted patients. Six patients were transplanted with purified CD34+ cells (selected by avidity column (Ceprate (R)), and had duration of thrombocytopenia and hospital stay similar to the patients transplanted with unmanipulated blood stem cells, but slightly longer duration of neutropenia. We conclude that high-dose therapy with autologous stem cell transplantation in not too heavily pretreated patients is a safe procedure irrespective of the source of stem cells.     

Transient contralateral hypoglossal nerve palsy following third molar surgery under day-case general anaesthesia: a case report and review of the literature

We have noticed that bone marrow transplanted in a vascularized limb graft providing a continuous supply of donor BMC may prolong the survival time of skin graft from the same donor. The question arises whether the raised microchimerism plays a role in the prolonged survival of skin allograft. The aim of the study was to follow the development of microchimerism after allogeneic vascularized bone marrow transplantation (VBMTx) concomitantly with the rejection processes of transplanted skin. The BN rats served as donors and LEW rats as recipients of VBMTx and free skin flap allograft. Hind limb was transplanted followed by a full-thickness skin graft on the dorsum. Cellular microchimerism was investigated in recipients of VBMTx and skin grafts in blood, spleen, mesenteric lymph node and bone marrow with monoclonal antibody OX27 directed against MHC class I polymorthic RTI on BN cells and quantitatively analysed in FACStar. In VBMTx group free skin flap survived 70 days after weaning of CsA. Intravenous infusion of BMC in suspension equivalent to that grafted in hind limb did not prolong skin graft survival after cessation of CsA therapy. Donor-derived cells could be detected in VBMTx recipients as long 70 days after wearing of CsA but not in recipients of i.v. suspension BMC grafting.     

A nonlethal conditioning approach to achieve engraftment of xenogeneic rat bone marrow in mice and to induce donor-specific tolerance

BACKGROUND: The supply of solid organs for transplantation will never meet the growing demand. Xenotransplantation is considered to be a potential solution for the critical shortage of allografts. However, xenograft rejection is currently not controlled by conventional immunosuppressive agents. Bone marrow chimerism induces donor-specific tolerance without the requirement for chronic immunosuppressive therapy. The aim of this study was to develop a nonlethal recipient-conditioning approach to achieve mixed bone marrow chimerism and donor-specific tolerance. METHODS: C57BL/10SnJ mice were conditioned with total body irradiation followed by a single injection of cyclophosphamide on day +2. On day 0, mice were reconstituted with untreated bone marrow cells from Fischer 344 rats. Recipients were analyzed by flow cytometry for donor bone marrow engraftment and multilineage chimerism. Donor-specific tolerance was tested by skin grafting. RESULTS: One hundred percent of recipients engrafted after irradiation with 600 cGy total body irradiation, transplantation with 80 x 10(6) Fischer 344 bone marrow cells, and injection with 50 mg/kg cyclophosphamide intraperitoneally. Donor chimerism was detectable in all engrafted animals for up to 11 months. This conditioning was nonlethal, because conditioned untransplanted animals survived indefinitely. Mixed xenogeneic chimeras were tolerant to donor-specific skin grafts but rejected third-party (Wistar Furth) grafts as rapidly as naive C57BL/10SnJ mice. In contrast, animals that received less efficacious conditioning regimens and did not exhibit detectable chimerism showed prolonged graft survival, but delayed graft rejection occurred in all animals within 10 weeks. CONCLUSION: The induction of bone marrow chimerism and donor-specific tolerance after nonlethal conditioning might be useful to prevent the vigorous cellular and humoral rejection response to xenografts.     

Status of microchimerism in recipients 15 years after living related kidney transplantation

To study the relevance of microchimerism to the long-term outcome of renal allografting, we analyzed the frequency of microchimerism in kidney transplant recipients who had stable graft function for 15 years or longer. Among the 104 recipients who underwent kidney transplantation between 1971 and 1980, 27 renal allografts (26%) are still functioning. Among these 27 patients, 13 recipients whose donor was still alive and cooperative were investigated for the presence of microchimerism in the peripheral blood and for their immunological status. Microchimerism was tested using the polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) method. To test the sensitivity of PCP-SSCP, the peripheral blood obtained within 5 weeks after transplantation (four kidney transplants, three liver transplants) was also examined. Microchimerism was detectable in five patients within 5 weeks of transplantation (kidney transplantation, 3/4; liver transplantation 2/3. However, in the patients studied 15 years after transplantation, microchimerism was detected in only one recipient (1/13). In this chimeric patient, mixed lymphocyte response revealed high responsiveness against donor antigen. In contrast, some patients who did not have chimerism showed donor-specific hyporesponsiveness in mixed lymphocyte response assay and did not develop antidonor antibody, according to flow cytometric analysis. Microchimerism is an infrequent state in the long-term survivors of kidney allografting, and this state is irrelevant to donor-specific unresponsiveness.     

Prevalence of asthma and wheeze in primary school children in northern Jordan

While the existence of chimeric cells in host tissue following organ transplantation is well documented, its distribution, temporal evolution and relationship to allograft survival is less clear. To explore this phenomenon, Lewis recipients of ACI cardiac allografts representing a wide range of immunosuppressive protocols and graft survival times were examined for the presence of chimerism using a sensitive polymerase chain reaction assay. Four groups of animals were examined: untransplanted animals receiving donor specific transfusion (DST)/cyclosporine A (CsA); allograft recipients with no treatment; recipients treated with DST/CsA/supplementary immunosuppression with rejection at 21-183 days; and recipients sacrificed with functioning allografts, treated with DST/CsA/supplementary immunosuppression and surviving > 200 days. To elucidate variations in the tissue distribution of chimeric cells, bone marrow, skin, liver, spleen, and thymus were examined in each animal. Untransplanted animals receiving DST/CsA displayed no evidence of chimerism. In animals receiving a cardiac allograft but no treatment, there was extensive evidence of chimerism in four of five animals. Chimerism was also detected in seven of nine animals with intermediate graft survival at the time of rejection. In animals with long-term graft survival, only four of eight displayed chimerism. These results suggest that, without immunosuppression, early chimerism does not lead to prolonged graft survival and that, even when graft survival is moderately prolonged, these cells are not sufficient to prevent rejection. In conclusion, chimerism appears to be a common phenomenon following transplantation, is not a result of DST, and may not be necessary for maintenance of long-term graft survival.     

A partial conditioning strategy for achieving mixed chimerism in the rat: tacrolimus and anti-lymphocyte serum substantially reduce the minimum radiation dose for engraftment

Development of partial conditioning strategies to achieve reliable engraftment of allogeneic bone marrow with minimum recipient morbidity could extend the therapeutic application of bone marrow transplantation (BMT) to enzyme deficiency states, hemoglobinopathies, autoimmune diseases, and the induction of tolerance for solid organ and cellular allografts. In this study we describe a nonmyeloablative rat BMT model and examine the effect of clinically available immunosuppressants on the minimum amount of total body irradiation (TBI) required for allogeneic engraftment. Donor ACI marrow was depleted of T cells using immunomagnetic beads and transplanted to major histocompatibility complex- and minor antigen-mismatched Wistar Furth (WF) rats (ACI --> WF) conditioned with varying doses of TBI. Recipients conditioned with TBI alone required myeloablation with 1000 cGy for reliable allogeneic marrow engraftment. Administration to WF recipients of a single dose of anti-lymphocyte serum (ALS) 5 days prior to BMT together with a limited course of tacrolimus (1 mg/kg/day) resulted in engraftment of ACI bone marrow at only 500 cGy TBI. ACI --> WF recipients were stable mixed chimeras (mean donor chimerism 49% at 330 days post-BMT). Chimerism was multilineage. All recipient animals were free of graft-versus-host disease. These results suggest that a nonmyeloablative conditioning strategy based on low-dose TBI and a limited course of tacrolimus plus ALS can produce long-term mixed multilineage chimerism.     

Conventional cytogenetics and FISH evaluation of chimerism after sex-mismatched bone marrow transplantation (BMT) and donor leukocyte infusion (DLI)

BACKGROUND AND OBJECTIVES: Sensitive and quantitative cytogenetic methods to better assess the biological significance of post-BMT chimerism have been recently developed. In this study, we compared the results of chimerism analysis and evolution employing conventional cytogenetics and fluorescence in situ hybridization (FISH) in 16 patients after sex-mismatched BMT, and in 5 patients after donor lymphocyte infusion (DLI) to treat post-BMT relapse. DESIGN AND METHODS: FISH studies were performed using separate digoxigenin labeled centromeric DNA probes for the X (pDMX1) and Y (DYZ1/DYZ3) chromosomes. To this purpose, different types of samples were used: bone marrow (BM) and peripheral blood (PB) slides processed for conventional cytogenetics, and routine BM and PB smears. RESULTS: Results of chimerism studies performed on different types of samples showed no significant differences. No significant differences in the ability to identify the sex of each cell with both pDMX1 and DYZ1/DYZ3 probes were found and the results obtained from independent experiments showed a high linear correlation. Chimerism analysis by FISH showed initial mixed chimerism after BMT in 10 patients. Seven of these patients were also studied by conventional cytogenetics and 2 of these showed mixed chimerism. Seven of the former 10 patients evolved to complete donor chimera. 6 patients showed cytogenetic or hematologic bone marrow relapse, 3 of which were preceded by mixed chimaerism as revealed by FISH studies. FISH studies permitted an easy and accurate monitorization of the response to DLI in 5 relapsed patients, showing an increase in the proportion of donor cells in 4 patients as they reached a new complete remission. INTERPRETATION AND CONCLUSIONS: Both FISH and conventional cytogenetics are quantitative methods to assess chimerism. However, FISH is more sensitive, accurate and can even be applied on routine BM and PB smears. Furthermore, its combination with immunophenotyping approaches to quantify chimerism on cell subpopulations, will help to clarify post-BMT chimerism significance.     

Which is the reality of Chagas disease in Argentina and in America?

Selective neutropenia lasting over five months occurred in a 17-year-old adolescent male who received an allogeneic bone marrow transplantation (BMT) from an HLA-identical sibling for severe aplastic anemia. Bone marrow specimens showed maturation arrest of myeloid precursor cells despite sustained engraftment. Cytogenetic analyses revealed complete donor-type chimerism in hematopoietic cells and mixed lymphoid chimerism. The patient received a second BMT from the same donor following more intensive conditioning, including total body irradiation. Neutrophil recovery was rapid and complete donor-type hematopoietic and lymphoid chimerism was observed within three weeks of the second transplant. The present case suggests that prolonged selective neutropenia following BMT is due to residual host-derived immunity which is resistant to the standard immunosuppressive conditioning used prior to BMT for aplastic anemia.     

Role of rHuEpo on blood transfusions in preterm infants after the fifteenth day of life

Ex vivo T cell depletion of allogeneic grafts is associated with a high (up to 80%) rate of mixed chimerism (MC) posttransplantation. The number of transplanted progenitor cells is an important factor in achieving complete donor chimerism in the T cell depletion setting. Use of granulocyte colony-stimulating factor (G-CSF) peripheral blood allografts allows the administration of large numbers of CD34+ cells. We studied the chimeric status of 13 patients who received allogeneic CD34+-selected peripheral blood progenitor cell transplants (allo-PBPCTs/CD34+) from HLA-identical sibling donors. Patients were conditioned with cyclophosphamide (120 mg/kg) and total-body irradiation (13 Gy in four fractions). Apheresis products were T cell-depleted by the immunoadsorption avidin-biotin method. The median number of CD34+ and CD3+ cells infused was 2.8x10(6)/kg (range 1.9-8.6x10(6)/kg) and 0.4x10(6)/kg (range 0.3-1x10(6)/kg), respectively. Molecular analysis of the engraftment was performed using polymerase chain reaction (PCR) amplification of highly polymorphic short tandem repeat (PCR-STR) sequences in peripheral blood samples. MC was detected in two (15%) of 13 patients. These two patients relapsed at 8 and 10 months after transplant, respectively. The remaining 11 patients showed complete donor chimerism and were in clinical remission after a maximum follow-up period of 24 months (range 6-24 months). These results were compared with those obtained in 10 patients who were treated with T cell-depleted bone marrow transplantation by means of elutriation and who received the same conditioning treatment and similar amounts of CD3+ cells (median 0.45x10(6)/kg; not significant) but a lower number of CD34+ cells (median 0.8x10(6)/kg; p = 0.001). MC was documented in six of 10 patients (60%), which was significantly higher than in the allo-PBPCT/CD34+ group (p = 0.04). We conclude that a high frequency of complete donor chimerism is achieved in patients receiving allo-PBPCT/CD34+ and that this is most likely due to the high number of progenitor cells administered.     

The kidney triggers graft-versus-host disease in experimental combined transplantation of kidney and stem cell-enriched peripheral leukocytes

As a preclinical step to human studies with combined stem cell-enriched peripheral leukocytes and organ transplantation from the same donor, a series of studies in rats was undertaken. These studies indicated that Lewis rats infused intravenously with major histocompatibility complex-incompatible (from Brown-Norway rats), stem cell-enriched peripheral leukocyte preparation alone never developed graft-versus-host disease (GHVD). However, GVHD invariably manifested in all animals a few days after the kidney was transplanted in rats that had been previously primed with stem cell-enriched peripheral leukocytes from the same kidney donor strain. GVHD was prevented by substituting the crude preparation of stem cell-enriched peripheral leukocytes with a purified preparation that was almost completely free of T lymphocytes. However, in these latter experiments all rats rejected their kidney graft within 10 days from the surgery. In rats previously given the crude stem cell-enriched peripheral leukocyte preparation, perioperative administration of the fusion protein CTLA4lg also prevented GVHD and prolonged kidney graft survival up to 106 to 175 days. By contrast, animals with kidney transplants, which were given CTLA4lg without stem cells, rejected their grafts within 35 days. All together, these findings may possibly contribute to the creation of rationally designed strategies of combining organ and bone marrow from the same donor to enhance mixed chimerism and prolong survival after organ transplantation.     

Effects of the intensity and timing of asbestos exposure on lung cancer risk at two mining areas in Quebec

BACKGROUND: Bone marrow transplantation (BMT) has been limited in the past by the availability of matched donors for patients. Over the past decade, the use of umbilical cord blood (UCB) as a source of hematopoietic stem cells has revolutionized the field of BMT, providing a source of hematopoietic stem cells for an increasing number of patients in need of a transplant. RESULTS: Umbilical cord blood transplantation (UCBT) appears to result in sustained engraftment of donor hematopoiesis similar to results achieved with marrow and peripheral blood hematopoietic stem cells. Early results indicate that UCBT is associated with a lower incidence and less severity of graft-versus-host disease than other sources of stem cells, potentially decreasing the morbidity and mortality of BMT. As the potential of UCBT has been realized, cord blood storage facilities have been established to provide UCB. The rapid emergence of UCBT has transformed a waste product of birth into a life-saving resource. Its use, however; has raised numerous ethical and medical concerns unique to this alternative source of stem cells. CONCLUSIONS: Umbilical cord blood transplantation represents a major advance in providing another stem cell source to patients in need of allogeneic hematopoietic stem cell transplantation. As with all new technologies, UCBT will have to be carefully studied over the next several years to determine its safety, efficacy, and precise indications in comparison with other sources of hematopoietic stem cells. The ethics of UCBT must properly respect the rights and needs of both donors and recipients.     

Donor helper T-cell frequencies as predictors of acute graft-versus-host disease in bone marrow transplantation between HLA-identical siblings

BACKGROUND: Despite the current level of sophistication of molecular typing for class I and class II alleles, a significant proportion (20-40%) of recipients of HLA-identical sibling marrow develop severe, acute graft-versus-host disease (GVHD) after bone marrow transplantation. It has been suggested that the frequency of patient-specific helper T lymphocyte precursors (HTLp) detected in the HLA-identical sibling donor correlates with the incidence and severity of acute GVHD after transplantation. METHODS: This study group consisted of 42 patients who all received bone marrow from HLA-identical sibling donors from January 1990 to December 1996. Using a limiting dilution analysis, donor HTLp frequencies were determined on samples collected before transplantation. The HTLp assay used the cytotoxic T-cell line, CTLL-2, which proliferates in the presence of interleukin-2. The reliability and reproducibility of this assay was established by using cryopreserved batches of CTLL-2 cells of known sensitivity. RESULTS: The recipient-directed HTLp frequencies detected in the donor before transplantation were correlated with the incidence and severity of acute GVHD experienced by the recipient after transplantation. Statistical analysis revealed an extremely significant correlation between donor precursor frequencies and the development of acute GVHD in the patient after transplantation (P<0.0001). CONCLUSIONS: This study suggests that together with molecular typing the HTLp frequency should be considered when selecting the most suitable sibling donor for bone marrow transplantation.