gammac gene transfer in the presence of stem cell factor, FLT-3L, interleukin-7 (IL-7), IL-1, and IL-15 cytokines restores T-cell differentiation from gammac(-) X-linked severe combined immunodeficiency hematopoietic progenitor cells in murine fetal thymic organ cultures

X-linked severe combined immunodeficiency (SCID-Xl) is a rare human inherited disorder in which early T and natural killer (NK) lymphocyte development is blocked. The genetic disorder results from mutations in the common gammac chain that participates in several cytokine receptors including the interleukin-2 (IL-2), IL-4, IL-7, IL-9, and IL-15 receptors. We have shown in a previous report that gammac gene transfer into SCID-Xl bone marrow (BM) cells restores efficient NK cell differentiation. In this study, we have focused on the introduction of the gammac gene into SCID-Xl hematopoietic stem cells with the goal of obtaining differentiation into mature T cells. For this purpose, we used the in vitro hybrid fetal thymic organ culture (FTOC) system in which a combination of cytokines consisting of stem cell factor (SCF), Flt-3L, IL-7, IL-1, and IL-15 is added concomitantly. In this culture system, CD34(+) marrow cells from two SCID-Xl patients were able to mature into double positive CD4(+) CD8(+) cells and to a lesser degree into CD4(+) TCRbeta+ single positive cells after retroviral-mediated gammac gene transfer. In addition, examination of the output cell population at the TCR DJbeta1 locus exhibited multiple rearrangements. These results indicate that restoration of the gammac/JAK/STAT signaling pathway during the early developmental stages of thymocytes can correct the T-cell differentiation block in SCID-Xl hematopoietic progenitor cells and therefore establishes a basis for further clinical gammac gene transfer studies.

Prevention of EBV-induced B-lymphoproliferative disorder by ex vivo marrow B-cell depletion in HLA-phenoidentical or non-identical T-depleted bone marrow transplantation

HLA-mismatched bone marrow transplantation (BMT) is hampered by three major complications: graft rejection, acute graft-versus-host disease (aGVHD) and delayed immune reconstitution. Infusion of anti-LFA1 plus anti-CD2 monoclonal antibodies (MAb), combined with ex-vivo T-cell depletion of the graft, was efficient in preventing graft rejection and aGVHD. Nevertheless, disease-free survival was limited by the high frequency of lethal infections, including EBV-induced lymphoproliferative disease (BLPD), which originates mostly from donor B cells, with an incidence of 5-30%. To decrease the rate of this complication, ex-vivo B-cell depletion was attempted. This study compares a group of 19 patients who received a T- and B-cell-depleted marrow from an HLA-mismatched related donor with a retrospective control group of 19 patients, who had received T-cell-depleted marrow by the same method. The level of T-cell depletion was similar in the two groups. For B-cell depletion, two different methods were compared. The median number of B cells infused in the study group was 0.46/kg. Engraftment and aGVHD incidence were similar in the two groups. No EBV donor-derived BPLD occurred in the study group, compared with seven in the control group, four of whom died because of EBV-BPLD. Event-free survival was significantly different between the two groups. We conclude that ex-vivo B-cell depletion of the graft may be a useful means of preventing EBV-BPLD, and warrants further study on a larger group of patients.

A human severe combined immunodeficiency (SCID) condition with increased sensitivity to ionizing radiations and impaired V(D)J rearrangements defines a new DNA recombination/repair deficiency

The products of recombination activating gene (RAG)1 and RAG2 initiate the lymphoid-specific phase of the V(D)J recombination by creating a DNA double-strand break (dsb), leaving hairpin-sealed coding ends. The next step uses the general DNA repair machinery of the cells to resolve this dsb. Several genes involved in both V(D)J recombination and DNA repair have been identified through the analysis of in vitro mutants (Chinese hamster ovary cells) and in vivo situations of murine and equine severe combined immunodeficiency (scid). These studies lead to the description of the Ku-DNA-dependent protein kinase complex and the XRCC4 factor. A human SCID condition is characterized by an absence of B and T lymphocytes. One subset of these patients also demonstrates an increased sensitivity to the ionizing radiation of their fibroblasts and bone marrow precursor cells. This phenotype is accompanied by a profound defect in V(D)J recombination with a lack of coding joint formation, whereas signal joints are normal. Functional and genetic analyses distinguish these patients from the other recombination/repair mutants, and thus define a new group of mutants whose affected gene(s) is involved in sensitivity to ionizing radiation and V(D)J recombination.

The feasibility of peripheral blood stem cell collection for autograft following failure in bone marrow aspiration

High doses of cytotoxic drugs may impair stem cell collection. Failure in stem cell collection by bone marrow aspiration can be rescued by harvesting Peripheral Blood Stem Cell (PBSC) after a combination of chemotherapy and hematopoietic growth factor. We, therefore, retrospectively evaluated the possibility of collecting PBSC after chemotherapy and/or G-CSF administration in 12 patients with insufficient Granulocyte-macrophage colony-forming unit (CFU-GM) counts after bone marrow aspiration (all patients had previously received heavy chemotherapy for hematologic malignancies); median collection of CFU-GM/kg count was 2,9 x 10(4)/kg (range 0,4 to 8 x 10(4)/kg) whereas the minimal count required for autografting is 10 x 10(4)/kg. Median collections of CFU-GM from PBSC were 5,8 x 10(4)/kg. While the CFU-GM collected in PBSC was higher than after bone marrow aspiration, only 5 patients had enough PBSC for autografting. In another case, addition of cells collected from both PBSC and bone marrow aspiration yielded a sufficient number of CFU-GM to allow autografting. Therefore in this selected and small group of patients, failure in bone marrow aspiration does not seem to be predictive of a low PBSC collection but a long therapy free interval and use of G-CSF alone for PBSC mobilization could constitute a valuable alternative. Three patients had a successful short term hematologic reconstitution out of the four patients having had an autograft.

Long-term immune reconstitution and outcome after HLA-nonidentical T-cell-depleted bone marrow transplantation for severe combined immunodeficiency: a European retrospective study of 116 patients

We have performed a retrospective analysis of the development of T- and B-cell functions after HLA-nonidentical T-cell-depleted bone marrow transplantation (BMT) performed in 193 patients with severe combined immunodeficiency (SCID) at 18 European centers between December 1982 and December 31, 1993. One hundred sixteen of 193 patients were alive with evidence of engraftment 6 months after BMT. Development of T-cell function occurred earlier than B-cell function and was achieved more frequently up to the time of last follow-up. The median time to achieve normal T-cell function was 8.7 months, whereas the median time to achieve normal B-cell function was 14.9 months. Twenty-four patients died later than 6 months post-BMT, mainly due to chronic graft-versus-host disease (cGVHD) and/or viral infection. Absence of T-cell reconstitution 6 months after BMT, unlike absence of B-cell reconstitution, was associated with a poor outcome. Two additional factors were associated with a poor outcome: presence of cGVHD 6 months after BMT and B- SCID versus B+ SCID. However, two of these three factors remained as significant prognostic factors in a multivariate analysis: the absence of T-cell function and the presence of cGVHD 6 months after BMT. Analysis of the factors influencing the development of immune reconstitution showed that T- and B-cell functions occurred earlier and more frequently in B+ SCID versus B- SCID patients. Acute GVHD was associated with a slower development of T-cell function at 6 months, and cGVHD had a negative influence on the development of T-cell function afterwards, but neither acute nor chronic GVHD was found to influence the development of B-cell function. Once engraftment occurred, whether patients had or had not received Busulfan in the conditioning regimen did not influence the kinetics and quality of T-cell function development. In a multivariate study, two factors were found to influence the T-cell function 6 months after BMT: type of SCID and acute GVHD. The results of this retrospective analysis should lead to new protocols adapted to SCID disease, considering that disease-related as well as BMT-related parameters influence the development of immune function and thereby long-term outcome after HLA-nonidentical T-cell-depleted BMT.

[Prevention of intestinal allograft rejection by anti-adhesion molecule antibodies in a mouse model]

STUDY AIM

Small bowel transplantation is still hampered by a high morbidity and mortality linked to the heavy non specific immunosuppression which is required by the transplantation of this lymphoid organ. Adhesion molecules appear to be potential targets for specific immunosuppression. The aim of the study was to investigate the effect of a transitory administration of anti-LFA-1 or anti-alpha 4 monoclonal antibodies (mAb) in the prevention of rejection in a model of fetal small-bowel transplantation in mice.

MATERIALS AND METHODS

The small bowel of C57BL/6 (H-2b) fetus (16 to 20 days of gestation) was transplanted into adult C3H/He mice (H-2k) or C57BL/6 recipient mice. Recipients were treated with a short course of either anti-LFA-1 mAb alone, either with anti-alpha 4 mAb alone, or with both mAb. Biopsies with histological study of the grafts were performed between post-operative day 5 and 60. A score of development and rejection was assigned to each sample.

RESULTS

Normal intestinal development with no sign of rejection was observed in 24/28 syngenic grafts till post-operative day 45. In the absence of treatment, intense rejection was observed as soon as day 5 and all allogenic grafts were rejected (n = 22). In contrast, in anti-LFA-1 mAb treated mice, 18/20 allogenic grafts developed normally with minimal signs of rejection. In anti-alpha 4 treated mice, a transient protective effect on small bowel allograft survival was observed on day 7 but thereafter, all grafts were massively rejected within a few days (n = 18). The combination of both mAb didn't improve the survival of the grafts when compared to anti-LFA-1 mAb treated grafts (n = 10).

CONCLUSION

These results demonstrate that a transitory administration of anti-LFA-1 mAb, but not of anti-alpha 4 mAb, is able to prolong significantly the survival of non vascularized small bowel fetal grafts in mice. Our results are promising for the possible use of the anti-LFA-1 mAb in clinical intestinal transplantation.

Treatment of familial hemophagocytic lymphohistiocytosis with bone marrow transplantation from HLA genetically nonidentical donors

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare genetic disorder associated with the onset early in life of overwhelming activation of T lymphocytes and macrophages invariably leading to death. Allogeneic bone marrow transplantation (BMT) from an HLA-identical related donor is the treatment of choice in patients with this disease. However, fewer than 20% of patients have a disease-free HLA-identical sibling. BMT from HLA-nonidentical related donors has previously met with poor results, with graft rejection a major obstacle in all cases. We describe BMTs from HLA-nonidentical related donors (n = 13) and from a matched unrelated donor (n = 1) performed in two centers in 14 consecutive cases of FHL. Remission of disease was achieved before BMT in 10 patients. Marrow was T-cell-depleted to minimize graft-versus-host disease (GVHD). Antiadhesion antibodies specific for the alpha chain of the leukocyte function-associated antigen-1 (LFA-1, CD11a) and the CD2 molecules were infused pre-BMT and post-BMT to help prevent graft rejection, in addition to a conditioning regimen of busulfan (BU), cyclophosphamide (CP), and etoposide (VP16) or antithymocyte globulin (ATG). Sustained engraftment was obtained in 11 of 17 transplants (3 patients had 2 transplants) and disease-free survival in 9 patients with a follow-up period of 8 to 69 months (mean, 33). Acute GVHD greater than stage I was not observed, and 1 patient had mild cutaneous chronic GVHD that resolved. Toxicity due to the BMT procedure was low. Results obtained using this protocol are promising in terms of engraftment and event-free survival within the limitations of the small sample. We conclude that an immunologic approach in terms of drugs used to obtain disease remission and a conditioning regimen that includes antiadhesion molecules in T-cell-depleted BMT from HLA genetically nonidentical donors is an alternative treatment that warrants further study in FHL patients who lack a suitable HLA genetically identical donor.

In vivo infusion of anti-LFA-1 and anti-CD2 antibodies prevents graft failure after HLA partially incompatible bone marrow transplantation in children with high risk acute lymphoblastic leukaemia

Bone marrow transplantation (BMT) from matched sibling donors is the therapy of choice for children with high-risk acute lymphoblastic leukaemia in children. It is however not available to more than two-thirds of patients who lack a matched donor. Here, we review the outcome of 28 patients with high-risk ALL who were transplanted in France with alternative marrow sources such as HLA-phenoidentical unrelated volunteers and HLA-partially incompatible relatives. For these patients, we tested the possibility to prevent T-depleted marrow graft rejection by infusing in vivo two monoclonal antibodies directed against adhesion receptors i.e., LFA-1 and CD2. Two previous multicenter trials in children transplanted with partially incompatible bone marrow for inborn errors of metabolism showed their efficacy in this setting. Twenty eight patients were enrolled in this study and followed for a median of 4.4 years. Bone marrow engraftment occurred in 81% of the evaluable patients. Post-transplantation leukaemic relapse was the most frequent cause of death in this group of patients, and occurred in 39% of patients. The second most frequent complication was infectious disease, while an EBV-induced B-lymphocyte proliferative disorder occurred in four patients. In conclusion, T-cell-depletion combined with infusion of anti-LFA-1 and anti-CD2 antibodies is efficient in preventing graft failure and GVHD in this group of children with high-risk leukaemia undergoing partially incompatible BMT. The overall DFS is not improved in contrast to what has been previously observed in patients with immunodeficiencies transplanted with a similar rejection prophylaxis. Other approaches are therefore needed aiming either at preserving donor T-cell mediated immunity or accelerating immune reconstitution.

[Antiviral immunodeficiency: EBV, CMV, adenovirus]

Patients undergoing bone marrow transplantation are susceptible to many different bacterial, fungal and viral infections. Among the viral pathogens, cytomegalovirus (CMV), Epstein-Barr virus (EBV), and adenovirus cause the greatest morbidity and mortality and have been the most common infectious causes of death following the grafting of allogeneic marrow. This great susceptibility to viral infections is due to the immunodeficiency in cellular and humoral immune responses lasting for months to years. Contributing factors are high-dose chemo/radiotherapy, graft-versus-host disease (GVHD) prophylaxis/treatment, GVHD itself, the degree of HLA disparity between donor and recipient and the underlying disease. Defects of T cell helper and cytotoxic functions contribute to the great incidence of viral infections. We described here the kinetic of immunological reconstitution and the role of T cell immunodeficiency. At day 30 to 40 after BMT, a minority of patients had recovery of virus-specific CD8+ T-cell response. Between day 40 and day 90 recovery of deficient CD8+ and CD4+ T cell responses occurred in the majority of the recipients of HLA identical BMT but only in the minority of the recipients of HLA partially incompatible BMT. New approaches should therefore be envisaged either to preserve donor T-cell-mediate immunity or tho accelerate immune reconstitution. Add-back of unmanipulated T-cells, or virus-specific T cells could improve antimicrobial defenses after BMT.

Correction of Fas (CD95) deficiency by haploidentical bone marrow transplantation

Recently, an inherited syndrome characterized by nonmalignant lymphoproliferation with autoimmune manifestations, caused by mutations of the Fas (CD95) receptor gene has been described. Because of disease severity, i.e. unremitting lymphoproliferation in a child with complete Fas deficiency, a haploidentical bone marrow transplantation (BMT) was performed despite the known resistance of Fas-deficient lpr mice to bone marrow transplantation. Marrow graft was rejected early; however, a second attempt using bone marrow from the mother led to engraftment and to control of lymphoproliferation and of autoimmune thrombocytopenia up to the last follow-up at 24 months after BMT. This single case shows that resistance to bone marrow engraftment caused by survival of Fas-deficient cells can be overcome.

Naturally occurring primary deficiencies of the immune system

Naturally occurring genetic disorders of the immune system provide many models for the study of its development and function. In a way, their analysis complements the information provided by the generation of genetic defects in mice created using homologous recombination techniques. In this review, the recent findings made in three areas are focused upon deficiencies in T cell differentiation and in T lymphocyte activation, and on the control process of peripheral immune response.

Role of interleukin-2 (IL-2), IL-7, and IL-15 in natural killer cell differentiation from cord blood hematopoietic progenitor cells and from gamma c transduced severe combined immunodeficiency X1 bone marrow cells

Natural killer (NK) cells are characterized by their ability to mediate spontaneous cytotoxicity against susceptible tumor cells and infected cells. They differentiate from hematopoietic progenitor cells. Patients with X-linked severe combined immunodeficiency (SCID X1) carry mutations in the gamma c cytokine receptor gene that result in lack of both T and NK cells. To assess the role of interleukin-2 (IL-2), IL-7, and IL-15 cytokines, which share gamma c receptor subunit, in NK cell differentiation, we have studied NK cell differentiation from cord blood CD34 (+) cells in the presence of either stem cell factor (SCF), IL-2, and IL-7 or SCF and IL-15. The former cytokine combination efficiently induced CD34 (+) CD7 (+) cord blood cells to proliferate and mature into NK cells, while the latter was also able to induce NK cell differentiation from more immature CD34 (+) CD7 (-) cord blood cells. NK cells expressed CD56 and efficiently killed K562 target cells. These results show that IL-15 could play an important role in the maturation of NK cell from cord blood progenitors. Following retroviral-mediated gene transfer of gamma c into SCID X1 bone marrow progenitors, it was possible to reproduce a similar pattern of NK cell differentiation in two SCID-X1 patients with SCF + IL-2 + IL-7 and more efficiently in one of them with SCF + IL-15. These results strongly suggest that the gamma c chain transduces major signal(s) involved in NK cell differentiation from hematopoietic progenitor cells and that IL-15 interaction with gamma c is involved in this process at an earlier step than IL-2/IL-7 interactions of gamma c are. It also shows that gene transfer into hematopoietic progenitor cells could potentially restore NK cell differentiation in SCID X1 patients.

Bone marrow transplantation from genetically HLA-nonidentical donors in children with fatal inherited disorders excluding severe combined immunodeficiencies: use of two monoclonal antibodies to prevent graft rejection

OBJECTIVE

For children with life-threatening inborn errors of metabolism without a matched related bone marrow donor, transplantation from an HLA genetically nonidentical donor is the only therapeutic option. To reduce the high risk of graft rejection in this setting without increasing the conditioning regimen, a protocol based on the infusion of an antiadhesion antibody directed against the CD11a (leukocyte function-associated antigen 1 [LFA-1]) molecule was performed by the European Bone Marrow Transplantation-European Society for Immunodeficiency group with promising results. To optimize engraftment, and thereby survival, further, the additional blockade of a second important leukocyte adhesion and signalization pathway mediated by the CD2 and LFA-3 interaction was attempted in a multicenter protocol conducted by the European Bone Marrow Transplantation-European Society for Immunodeficiency group. Results of this study (ie, engraftment and survival) were compared with a historical control group that received the anti-LFA-1 antibody alone. Factors that may have affected engraftment and survival were also considered in this study.

METHODS

Forty-four children with inborn errors, including inherited immunodeficiencies (excluding severe combined immunodeficiencies), Chédiak-Higashi syndrome, familial hemophagocytic lymphohistiocytosis, and malignant osteopetrosis, received bone marrow from HLA-nonidentical related donors or from HLA-identical unrelated donors at 13 European centers between August 1990 and June 1993. Bone marrow was depleted of T cells by use of either erythrocyte (E) rosetting or monoclonal antibodies (MoAbs) to prevent graft-versus-host disease. The conditioning regimen consisted of busulfan and cyclophosphamide for all patients plus etoposide for patients with osteopetrosis, familial hemophagocytic lymphohistiocytosis, and Chédiak-Higashi syndrome. Infusions of MoAbs specific for the CD11a and the CD2 molecules were started 4 and 3 days, respectively, before and continued through the first 10 and 11 days, respectively, after bone marrow transplantation (a total of 14 injections).

RESULTS

The overall sustained engraftment rate was 69.8%, with full chimerism in 80.6% of patients and no late graft rejection with the use of two MoAbs versus 65.7% and 58.1%, respectively, in the control group, in which only one MoAb was infused. The overall actuarial survival rate with a functional graft was 40.9%, with a mean follow-up of 39.3 months with two MoAbs versus 37.8% with one. The engraftment rate was significantly influenced by the T-cell depletion method, with better results for recipients of E rosette- depleted marrow (78.6% vs 20% for Campath 1-M plus complement-depleted marrows). Graft-versus-host disease and the kinetics of immune reconstitution were similar in both groups.

CONCLUSIONS

The overall engraftment rate and overall survival rate with engraftment in patients treated with anti-LFA-1 and anti-CD2 were similar to those in patients treated with anti-LFA-1 antibody alone. However, although the number of patients is too small to draw definitive conclusions, results from the combined use of the two MoAbs indicates a trend toward better engraftment and survival after infusion of E rosette-depleted marrow. Further improvement in survival would demand additional strategies to hasten immunologic recovery.

Bone marrow transplantation in 26 patients with Wiskott-Aldrich syndrome from a single center

We retrospectively analyzed the outcome of bone marrow transplantation (BMT) performed in 26 patients with Wiskott-Aldrich syndrome (WAS) in one center. Twenty-eight transplantation procedures were performed. Ten unselected patients received unmanipulated marrow from a donor with genetically identical human leukocyte antigen (HLA). Eight patients were cured and survive 1.5 to 16.5 years after BMT. One patient successfully received a T-cell-depleted marrow from a matched unrelated donor. Sixteen patients were selected to receive a related HLA partially incompatible BMT because of the occurrence of life-threatening complications from the WAS (i.e., refractory thrombocytopenia, autoimmunity including vasculitis and sepsis). All but one received T-cell-depleted marrow after a conditioning regimen of busulfan and cyclophosphamide. One patient had two BMTs. Engraftment occurred in 12 of 17 attempts. The addition of monoclonal antibodies to lymphocyte function-associated antigen-1 and CD2 molecules appeared to improve engraftment. Six patients were long-term survivors, whereas others died of viral infections (n = 7), among which Epstein-Barr virus-induced B-lymphocyte proliferative disorder was predominant. Delay in development of full T- and B-cell functions accounted for severe infectious complications. These results confirm the excellent outcome of HLA genetically identical BMT in WAS, whereas BMT from HLA partially incompatible donors should be strictly restricted to patients with severe complications of WAS.

Lack of detectable defect in DNA double-strand break repair and DNA-dependent protein kinase activity in radiosensitive human severe combined immunodeficiency fibroblasts

The initial step of the V(D)J recombination occurs through the generation of a DNA double-strand break (dsb). Defects in the DNA-dependent protein kinase complex (DNA-PK) result in an inability to perform either V(D)J recombination or any dsb repair effectively. The human autosomal T-B-severe combined immunodeficiency (SCID) condition is characterized by an absence of both B and T lymphocytes and is accompanied in some patients by an increase in gamma-ray sensitivity (T-B-RS SCID) comparable to that found in mouse SCID cells. We show here that cells from six patients with T-B-RS SCID had normal DNA-dsb repair kinetics. Furthermore, DNA-PK activity was present in extracts from these human T-B-RS SCID fibroblasts. We therefore conclude that some human T-B-RS SCID disorders are not caused by a defect in an essential DNA-PK component.

gamma-c gene transfer into SCID X1 patients' B-cell lines restores normal high-affinity interleukin-2 receptor expression and function

SCID X1 is characterized by faulty T-cell and natural killer cell differentiation caused by mutation of the gamma-c chain gene encoding a number of multiple cytokine receptors (interleukin-2 [IL-2], IL-4, IL-7, IL-9, and IL-15 receptors). To assess the feasibility of inducing long-term expression and function of the gamma-c chain, Epstein-Barr virus (EBV)-transformed B-cell lines from two patients with SCID X1 were transduced with a Moloney-derived retroviral vector containing the gamma-c chain cDNA. The viral LTR was used as the promoter. Immediately after two cycles of coculture with the psi-crip clone producing the MFG(B2)-gamma-c cDNA vector, gamma-c expression, assessed by detection of the mRNA and membrane protein expression, was found in 15% to 20% of cells. The degree of membrane expression was similar to that in control EBV-B cells. Expression increased steadily over 6 months, becoming detectable in 100% of cells, and remained stable thereafter for a total of 9 months, reflecting positive selection of transduced cells. A study of provirus integration sites showed multiple integration. The expressed gamma-c was functional, because it restored high-affinity IL-2 receptor binding, IL-2 endocytosis, and IL-2-triggered phosphorylation of JAK-3 tyrosine kinase. Similar results were obtained with the two B-cell lines. These results show that efficient gamma-c gene transfer into B-cells lacking functional gamma-c is feasible and results in strong and stable expression of a functional gamma-c chain, apparently conferring a selective growth advantage in culture. Further in vitro studies of gamma-c gene transfer into gamma-c- hematopoietic progenitors are being conducted to assess the feasibility of correcting lymphocyte differentiation defects.

A phase II trial of partially incompatible bone marrow transplantation for high-risk acute lymphoblastic leukaemia in children: prevention of graft rejection with anti-LFA-1 and anti-CD2 antibodies. Société Française de Greffe de Moelle Osseuse

Bone marrow transplantation (BMT) from matched sibling donors has been useful for the treatment of acute lymphoblastic leukaemia in children with a poor prognosis but is not available to more than two-thirds of patients who do not have a matched allogeneic donor. This study was undertaken to assess one strategy of marrow graft rejection prevention when alternative marrow sources such as HLA-phenoidentical unrelated volunteers and HLA-partially incompatible relatives were used. Results have been compared with two matched groups of children with the same risks factors and disease status who underwent HLA-genoidentical or autologous BMT. The conditioning regimen was the same for the three groups of patients; in the study group anti-LFA-1 and anti-CD2 monoclonal antibodies combined with T-cell depletion of the marrow was added to prevent graft rejection and graft-versus-host disease. Nineteen patients were included and followed for a median of 25 months (14 months to 3 years). Bone marrow engraftment occurred in 83% of the evaluable patients. Post-transplantation infectious diseases were the most frequent causes of death in the study group, occurring in 31% of patients. No fatal infections occurred in the two control groups. Post-transplantation relapse of leukaemia occurred in 26% of study group's patients, in 58% of autologous BMT control group's patients and 5% of HLA-genoidentical allogeneic group's patients. The event-free survival was 83% in the HLA-genoidentical control group, and 30% and 24% in the study group and in the autologous control group, respectively. In conclusion, a high rate of engraftment was achieved by the use of anti-LFA-1 and anti CD2 antibodies. Occurrence of a long-lasting immunodeficiency, however, led to a high incidence of lethal infections and relapses. Combined approaches are therefore to be investigated accelerating immune reconstitution after transplantations of T-depleted HLA partially incompatible marrow.

Results of allogeneic bone marrow transplantation in patients with leukocyte adhesion deficiency

We have retrospectively analyzed the outcome of bone marrow transplantation (BMT) in 14 patients with leukocyte adhesion deficiency (LAD) performed in two centers between 1981 and 1993. Five patients received BMT from HLA-identical donors. Nine received T-depleted marrow from two HLA antigen- or haplotype-incompatible parents. Conditioning regimen consisted of chemotherapy exclusively in 13 patients and associated with total body irradiation (TBI) in one patient. In five cases, failure of engraftment occurred as a result of either insufficient myeloablation (n = 3) or, possibly, graft rejection in two cases of moderate phenotype of LAD. The second conditioning regimen consisted of TBI and chemotherapy with the use of anti-lymphocyte function-associated antigen 1 (LFA-1) and anti-CD2 monoclonal antibodies for patients with the moderate phenotype of LAD. These patients were successfully retransplanted. Eight patients developed acute graft-versus-host disease (GVHD). Chronic GVHD occurred in five cases. GVHD led to the death of three patients. Ten patients are alive and well 12 months to 12 years after BMT. Chimerism is full in six of these patients and mixed but stable in four with variable proportion of donor leukocytes. One patient with less than 15% donor leukocytes has mild gingivitis, while the others are well. Sequelae from BMT are limited in two cases to growth retardation caused by TBI. Success of BMT in cases of LAD including seven of nine recipients of HLA nonidentical marrow indicates that this procedure can be proposed as a curative approach to LAD regardless of an available HLA-identical donor. Great care should be taken in GVHD prophylaxis and treatment.

Characteristics of antigen-independent and antigen-dependent interaction of dendritic cells with CD4+ T cells

Dendritic cells (DC) are the main antigen-presenting cells for the initiation of primary T cell-mediated immune responses. In the first stage of activation, T cells bind to DC in an antigen-independent manner. We studied the adhesion characteristics of human CD4+ T cells to DC generated from CD34+ hematopoietic progenitors following 12 to 13 days of culture in the presence of granulocyte/macrophage colony-stimulating factor and tumor necrosis factor-alpha. A majority of these cells had the morphology, phenotype and functions of DC. CD4+ T/DC adhesion was measured by means of fluorescence microscopy and flow cytometry. Four independent receptor/ligand pathways, LFA-1/ICAM, ICAM/LFA-1, CD2/LFA-3 and CD28/CD80, were involved in the transient adhesion of DC to CD4+ T cells in antigen-independent and specific alloantigen-dependent situations, as shown by blocking experiments using monoclonal antibodies. The antibodies also blocked a primary mixed lymphocyte reaction (MLR) in which DC were used as stimulatory cells. Adhesion of alloreactive CD4+ T cells to antigen-presenting DC was stronger than that of resting CD4+ T cells, while peak adhesion occurred after 5 and 20 min, respectively. The LFA-1 ligands involved in adhesion of resting CD4 T cells to DC and alloreactive CD4+ T cells to specific DC differed in part, since ICAM-3 on resting T cells and ICAM-1 on alloreactive T lymphocytes preferentially bound LFA-1. Studies of interactions between DC and phorbol ester-activated T cells expressing the CD40 ligand revealed a fifth independent adhesion pathway, CD40/CD40 ligand. CD4-mediated regulation of CD4+ T/DC adhesion was suggested by the observation that preincubation of CD4+ T cells and DC individually with anti-CD4 antibodies inhibited adhesion. In addition, antibodies specific for HLA class II molecules inhibited adhesion when used to pretreat DC but not alloactivated CD4+ T cells.

Treatment of Omenn syndrome by bone marrow transplantation

We report the outcome of allogeneic bone marrow transplantation (BMT) in nine consecutive patients with Omenn syndrome treated between 1980 and 1989. Five patients received unmanipulated marrow from a related matched donor, and four received T cell-depleted marrow from a haploidentical donor. The patients were conditioned with cyclophosphamide (200 mg/kg) and, except in one case, busulfan (16 mg/kg). Antithymocyte globulin and etoposide were given to three patients each; three recipients of T cell-depleted haploidentical marrow also received intravenous injections of an anti-leukocyte function-associated antigen type 1 antibody as graft rejection prophylaxis. All the patients were fed parenterally for 1 to 5 months before BMT to improve nutritional status and received topical corticosteroids (n = 8), systemic steroids (n = 2), etoposide (n = 1), or cyclosporine (n = 1) to control T-cell activation. Engraftment occurred in four of five recipients of human leukocyte antigen (HLA)-identical marrow and three of four recipients of HLA-haploidentical marrow. One patient died with cytomegalovirus infection. The other six patients are alive 4 to 11 years after BMT, with full chimerism in all but one case. Chronic graft-versus-host disease persists in one patient; the other five survivors have fully restored immune function and have no manifestations of Omenn syndrome, including failure to thrive. We conclude that both HLA-identical and haploidentical BMT can cure Omenn syndrome, provided that parenteral nutrition and immunosuppressive therapy are given before transplantation.

Prevention of bone marrow and cardiac graft rejection in an H-2 haplotype disparate mouse combination by an anti-LFA-1 antibody

The aim of the present study was to compare the preventive effect of a nondepleting monoclonal antibody specific for the LFA-1 alpha chain (CD11a) on the rejection of bone marrow, vascularized cardiac, and nonvascularized skin grafts in the same haplotype-disparate mouse strain combination. A 7-day treatment with a total dose of 0.5 mg of anti-LFA-1 antibody (H-129) had no effect on the rejection of BDF1(H-2b/d) skin grafts by CDF1 (H-2k/d)-treated mice. In contrast, the same treatment regimen significantly prolonged the survival of BDF1 cardiac allografts in CDF1 mice: 7 out of 10 mice had a functional graft after 70 days, whereas all control mice had rejected their graft by 11 days. Nevertheless, cardiac allografts were ultimately rejected. In contrast, infusion of anti-LFA-1 antibody was able to promote definitive engraftment of T-depleted BDF1 marrow in 9 gray-irradiated CDF1 recipients: in surviving mice, engraftment increased from 10% in controls to 78% in antibody-treated recipients. In mice that tolerated their cardiac graft for more than 70 days, there was a slight delay in the rejection of donor skin graft but no in vitro evidence of tolerance. In contrast, mice with successful marrow engraftment did not reject donor skin graft and failed to mount proliferative and cytotoxic responses against donor alloantigens, whatever the percentage of engrafted donor leukocytes. These results indicate that a nondepleting anti-LFA-1 antibody can efficiently protect against rejection of MHC-incompatible heart and bone marrow. The protective effect of anti-LFA-1 antibody was associated with the induction of T cell tolerance toward donor antigens after bone marrow transplantation.

Bone marrow transplantation in major histocompatibility complex class II deficiency: a single-center study of 19 patients

Major histocompatibility complex (MHC) class II deficiency (bare lymphocyte syndrome) is a rare inborn error of the immune system characterized by impaired antigen presentation and combined immunodeficiency. It causes severe and unremitting infections leading to progressive liver and lung dysfunctions and death during childhood. As in other combined immunodeficiency disorders, bone marrow transplantation (BMT) is considered the treatment of choice for MHC class II deficiency. We analyzed the files of 19 patients who have undergone BMT in our center. Of the 7 patients who underwent HLA-identical BMT, 3 died in the immediate posttransplant period of severe viral infections, whereas the remaining 4 were cured, with recovery of normal immune functions. Of the 12 patients who underwent HLA-haplo-identical BMT, 3 were cured, 1 was improved by partial engraftment, 7 died of infectious complications due to graft failure or rejection, and 1 is still immunodeficient because of engraftment failure. A favorable outcome in the HLA-non-identical BMT group was associated with an age of less than 2 years at the time of transplantation. All the patients with stable long-term engraftment had persistently low CD4 counts after transplantation (105 to 650/microL at last follow up), but no clear susceptibility to opportunistic infections despite persisting MHC class II deficiency on thymic epithelium and other nonhematopoietic cells. We conclude that HLA-identical and -haploidentical BMT can cure MHC class II deficiency, although the success rate of haploidentical BMT is lower than that in other combined immunodeficiency syndromes. HLA-haploidentical BMT should preferably be performed in the first 2 years of life, before the acquisition of chronic virus carriage and sequelae of infections.

Treatment of juvenile chronic myelomonocytic leukemia by allogeneic bone marrow transplantation

Twelve of 15 patients with juvenile chronic myelomonocytic leukemia (JCMML) referred to our unit underwent allogeneic bone marrow transplantation (BMT) between 1982 and 1992. BMT was not performed in the remaining three cases because of poor overall condition in two and disease progression in one. Six patients received marrow from HLA-identical siblings after a chemotherapy conditioning regimen in five cases. BMT failed in one case. Long-term remission was achieved in three patients and two others are in remission 6 and 11 months after BMT. Remission was associated with autologous recovery in one patient and minimal mixed chimerism in another. In one patient, a first BMT procedure resulted in autologous recovery and relapse. A second transplant, with chemotherapy conditioning including TBI, was successful. BMT with marrow from a matched unrelated donor was also successful. IN contrast, BMT with marrow from mismatched related donors (five patients) failed because of graft failure and/or relapse. This single-center series indicates that HLA-identical BMT is an appropriate treatment for JCMML. However, on the basis of these results it cannot be ascertained whether chemotherapy or splenectomy are necessary prior to BMT. The best chemotherapy conditioning regimen remains to be defined, as regimens consisting exclusively of chemotherapy resulted either in long-term remission or in autologous recovery with relapse.

Bone marrow transplantation (BMT) in Europe for primary immunodeficiencies other than severe combined immunodeficiency: a report from the European Group for BMT and the European Group for Immunodeficiency

Bone marrow (BM) transplantations performed between 1977 and 1991 at 13 European centers in 149 patients with 11 different primary immunodeficiency (ID) diseases (excluding severe combined immunodeficiency) were analyzed retrospectively. Overall survival among recipients of HLA genetically identical BM (n = 56) was 66%. Since October 1985, the date of a previous survey, a significant improvement in survival has been achieved in most ID diseases (overall survival, 81.5% v 51.7%; P < .01), primarily because of a decrease in the frequency of infectious complications. In long-term survivors, disease correction is excellent, with minimal sequelae in most patients. In 22 patients who received closely matched BM (ie, from phenotypically identical related donors, matched unrelated donors, or one HLA-ag-mismatched related donors), the survival rate (45.5%) was not significantly better than among 71 recipients of BM with 2 or 3 mismatched HLA antigens (38%). In the latter group, favorable outcome was associated with younger age, with transplantation since October 1985 (47% v 25%; P < .0001), and with a diagnosis of leukocyte adhesion deficiency. The improvement in outcome was mainly because of a higher engraftment rate and a decrease in the frequency of infections, although Epstein-Barr virus-induced B-lymphocyte proliferative disorders occurred in 16 patients (mainly those with Wiskott-Aldrich syndrome), 10 of whom died. The improvement in engraftment corresponded to the introduction of treatment in vivo with anti-LFA-1 antibody to prevent rejection of T-cell-depleted grafts (74% engraftment and 45% survival in 38 treated patients versus 37.5% and 21%, respectively, in 24 untreated patients.

Attenuation of graft-versus-host disease and graft rejection by ex vivo immunotoxin elimination of alloreactive T cells in an H-2 haplotype disparate mouse combination

A mouse anti-interleukin-2 receptor A-chain-specific PC61-immunotoxin (PC61-IT) strongly inhibited a primary mixed lymphocyte culture and major histocompatibility complex (MHC)-restricted cytotoxicity. The allodepleted T cells retained their proliferative and cytotoxic capacities in response to third-party stimulation, showing that PC61-IT specifically deleted recipient antigen-specific T-cell clones from the donor mouse. The ability of this specific allodepletion to prevent graft-versus-host disease (GVHD) and graft rejection was investigated in vivo. IT-depleted, activated parental T lymphocytes (C3H/eB) were intravenously injected into lethally irradiated CDF1 mice. GVHD was evaluated after 6 days on the severity of gut lesions. PC61-IT-treated cells significantly reduced both donor T-cell infiltration and acceleration of epithelial renewal (a sensitive index of gut damage) as compared with those for the corresponding untreated controls. The effect of selective allo-depletion on prevention of GVHD and graft rejection was further studied after MHC-haploincompatible bone marrow (BM) transplantation. A significant increase in survival was observed in mice receiving 2 x 10(6) T-cell-depleted BM cells and 0.5 x 10(6) PC61-IT-treated T cells, because one-third were alive without GVHD (and with stable full or partial engraftment) after 100 days, whereas all the mice infused with BM and sham-treated T cells died within 80 days from GVHD, and all the mice infused with BM cells alone rejected grafts. Furthermore, specific tolerance in chimeras towards donor cells could be shown. These results as observed in an experimental in vivo model corroborate previous results obtained in vitro in humans and lead us to consider the use of this selective allodepletion in human BM transplant from donors other than identical familial siblings.

Increased radiosensitivity of granulocyte macrophage colony-forming units and skin fibroblasts in human autosomal recessive severe combined immunodeficiency

We studied the radiosensitivity of granulocyte macrophage colony-forming units (GM-CFU) in patients with a severe combined immunodeficiency (SCID). Three patients lacking both mature T and B cells showed a twofold higher GM-CFU radiosensitivity calculated as the DO value (dose required to reduce survival to 37%), and an identical observation was made with fibroblasts from one of these patients. A patient with an SCID with hypereosinophilia, i.e., Omenn's syndrome characterized by extremely restricted T cell heterogeneity and a lack of B cells, also showed abnormal GM-CFU radiosensitivity. In contrast, GM-CFU from a patient lacking only T cells (X-linked form of SCID) showed normal GM-CFU radiosensitivity. These data further support the similarity between human T(-) B(-) SCID and the murine acid mutation characterized by a defect in T cell receptor and immunoglobulin gene rearrangement, and by an abnormal double-strand DNA break repair function. In addition, they strongly suggest that the Omenn's immunodeficiency syndrome may be a leaky T(-)B(-) SCID phenotype as previously indicated by the coexistence of the two phenotypes in siblings.

[Residual lymphocytes after specific depletion. Functional study]

We previously demonstrated that, following a 2-day stimulation of T cells by MHC incompatible cells, a ricin A-chain conjugated to a monoclonal anti-IL2 receptor p55 subunit can kill 1.5 log of the activated alloreactive T cells while non specific killing of alloreactive T cells of a third partner does not exceed 0.5 log. This methodology is of potential use for selective alloreactive T cell depletion in MHC incompatible bone marrow transplantation in order to prevent both graft versus host disease and graft rejection. This study shows that this T cell depletion method does not alter T cell reactivity to microorganism antigens encountered in infection following BMT. It was found that T cell proliferation to cytomegalovirus and to candida antigens is not affected as shown in proliferative assays and by limiting dilution analysis for the latter antigen.

Specific elimination of alloreactive T cells by an anti-interleukin-2 receptor B chain-specific immunotoxin

Graft-versus-host disease and graft rejection remain the two principal causes of morbidity and mortality after major-histocompatibility-complex-mismatched bone marrow transplantation. Human and animal models suggest that both CD4+ and CD8+ T cell subsets present in the donor inoculum are responsible for their initiation. Since the human mixed lymphocyte culture (MLC) and the HLA-restricted cytotoxicity may reflect cellular interactions occurring during GVHD and graft rejection, inhibitions of these responses may represent useful approaches for screening functional T cell depletion in experimental bone marrow transplantation studies. For this purpose, we have tested the possibility of removing the host-specific allogeneic T cells present in the marrow. After a two-day MLC, the specifically activated host alloreactive blood or bone marrow T cells were incubated with the ricin A-chain toxin conjugated with the antibody 33B3.1 directed against the human receptor of interleukin 2 (33B3.1-IT). A complete inhibition of a primary MLC and of cytotoxic activities was observed as well as a disappearance of IL-2R(+) (p55) T cells. This method had limited consequence upon the alloreactivity of blood or marrow T cells toward a third unrelated party. The limiting-dilution analysis of residual alloantigen-reactive T lymphocytes has shown that this depletion results in a twentyfold to fiftyfold reduction of antihost reactivity. The procedure was also shown not to inhibit the growth of marrow precursors for granulocytes and macrophages.