European experience of bone-marrow transplantation for severe combined immunodeficiency

Association of reticular dysgenesis (thymic alymphoplasia and congenital aleukocytosis) with bilateral sensorineural deafness

Reticular dysgenesis is a rare congenital disorder characterized by severe combined immunodeficiency and profound neutropenia, curable to date, only by bone marrow transplantation. This report describes the association of bilateral sensorineural deafness with this disease.

Bone marrow transplantation for canine X-linked severe combined immunodeficiency

Canine X-linked severe combined immunodeficiency (XSCID) is due to mutations in the common gamma chain which is a subunit of the receptors of IL-2, IL-4, IL-7, IL-9 and IL-15. Bone marrow transplantation (BMT) of human XSCID patients without pretransplant conditioning (cytoablation) results in engraftment of donor T-cells and reconstitution of T-cell function but engraftment of few, if any, donor B cells with resultant poor reconstitution of humoral immune function. In this study, we show that XSCID dogs can be transplanted with allogeneic bone marrow cells resulting in engraftment of both donor B and T cells and reconstitution of full systemic immune function including normal humoral immune function without the need for cytoablation.

Deficient cellular immunity--finding and fixing the defects

The critical role of cellular immunity in resistance to infectious diseases is glaringly revealed by life-threatening infections if T cell function is disrupted by an inherited or acquired immunodeficiency. Although treatment has historically focused on infectious complications, understanding of the cellular and molecular basis of immunodeficiency and technologies useful for enhancing cellular immunity have both been rapidly evolving. A new era of molecular and cellular therapy is emerging as approaches to correct abnormal genes, the loss of T cell subpopulations, and aberrant T cell homeostasis make the transition from bench to bedside.

In utero hematopoietic stem cell transfer: current status and future strategies

Successful prenatal treatment of severe immunodeficiencies by allogeneic hematopoietic stem cell transplantation in utero has been reported. Though other diseases like hemoglobinopathies or storage diseases are potentially amenable to this novel therapeutic approach, no success has yet been achieved in recipients without severe immunodeficiency. Graft rejection by the developing fetus and/or lack of selective, competitive advantage of donor versus host stem cells preventing stable engraftment seem to be the major obstacles. Several strategies to overcome these hurdles are being explored in preclinical settings, including timing and repeated dosing of stem cell administration to the fetus, ex vivo modification of the transplant, using different fetal compartments as targets for early stem cell transfer, or inducing microchimerism for postnatal transplantation from the same donor. In addition, the exact definition of the basic concept of early fetal immunologic naivete and the understanding of the molecular basics of migration and homing in fetal hematopoiesis system seem mandatory for a successful approach. Gene therapy using ex vivo transduced autologous cord blood cells or direct gene targeting in utero are other potential means to correct hematopoietic and immunologic single gene disorders in utero, though this approach is still away from the stage of clinical trials.

Influence of severe combined immunodeficiency phenotype on the outcome of HLA non-identical, T-cell-depleted bone marrow transplantation: a retrospective European survey from the European group for bone marrow transplantation and the european society for immunodeficiency

We analyzed the outcomes of 214 HLA non-identical T-cell-depleted bone marrow transplantations (BMTs), performed in 178 consecutive patients for treatment of severe combined immunodeficiencies (SCID). Patients were treated in 18 European centers between 1981 and March 1995. SCID variants, that is, absence of T and B lymphocytes (B-) or absence of T cells with presence of B lymphocytes (B+) were found to have a major influence on outcome. The disease-free survival was significantly better for patients with B+ SCID (60%) as compared with patients with B- SCID (35%) (P =.002), with a median follow-up of 57 months and 52 months, respectively. Other factors associated with a poor prognosis were the presence of a lung infection before BMT (odds ratio = 2.47 [1.99-2.94]) and the use of monoclonal antibodies for T-cell depletion of the graft (odds ratio = 1.67 [1. 18-2.15]). Additional factors influencing outcome were age at BMT (<6 months) and period during which BMT was performed. Better results were achieved after 1991. Reduced survival of patients with B- SCID was associated with a higher incidence of early deaths from infection, a diminished rate of marrow engraftment, a trend to a higher incidence of chronic graft-versus-host disease, and slower kinetics of T/B immune function development. In both groups of patients, the use of busulfan (8 mg/kg total dose) and cyclophosphamide (200 mg/kg total dose) as a conditioning regimen provided the best cure rate (74% for patients with B+ SCID and 43% for patients with B- SCID, respectively), although results were not statistically significantly different from other regimens. This retrospective analysis should lead to the design of adapted measures to the performance of HLA non-identical BMT in patients with distinct SCID conditions.

Kinetics of T-cell development of umbilical cord blood transplantation in severe T-cell immunodeficiency disorders

BACKGROUND

Hematopoietic stem-cell transplantation is the treatment of choice for severe primary T-cell immunodeficiencies. When an HLA-identical sibling donor is not available, an alternative donor stem-cell source is needed. In primary T-cell immunodeficiencies, T-cell-depleted HLA-haploidentical bone marrow transplantation has been particularly successful in reconstituting the T-cell immune system in many of the severe combined immunodeficiency syndrome types. However, there are some problems associated with this preparation as a stem donor source, such as increased resistance to engraftment, a long period of time for T-cell engraftment to occur, and failure to engraft B cells and B-cell functions. These problems can be especially troublesome if the patient is infected before the transplantation.

OBJECTIVE

Umbilical cord blood was evaluated as a stem-cell source for immune reconstitution in children with severe primary T-cell immunodeficiency disorders, such as severe combined immunodeficiency syndrome, reticular dysgenesis, thymic dysplasia, and combined immunodeficiency disease, when a matched sibling donor was unavailable.

METHODS

From January 1996 through July 1997, 6 children received unrelated cord blood stem-cell transplantation after a preparative regimen for the treatment of combined immunodeficiency diseases. The patients ranged in age from 2 weeks to 6 years. The cord blood units were 3 of 6 HLA antigen matches in 2 children, 4 of 6 HLA antigen matches in 3 children, and 5 of 6 HLA antigen matches in 1 child, with molecular HLA-DR mismatch in 3 of the children.

RESULTS

The average time for neutrophil engraftment (absolute neutrophil count, >500/mm3) was 12 days (range, 10 to 15 days), and the average time for platelet engraftment (platelet count, >20,000/mm3) was 36 days (range, 24 to 50 days). In a patient with reticular dysgenesis, the first transplant failed to engraft but fully engrafted after a second unrelated donor cord blood transplantation. Five of 6 patients exhibited grade I graft-versus-host disease (GvHD), although 1 child experienced grade IV skin and gut GvHD. Immunologic reconstitution demonstrated that cord blood stem-cell transplantation resulted in consistent and stable T-cell, B-cell, and natural killer-cell development. The kinetics of recovery of phenotypic expression and function of T cells occurred between 60 to 100 days and that of natural killer cells at approximately 180 days. B cells engrafted early, and a study of functional B-cell antibody responses revealed that 2 of 2 patients in whom intravenous immune globulin was discontinued have low detectable antibody responses to tetanus and diphtheria toxoid immunizations more than 1 year after the transplantation.

CONCLUSIONS

Unrelated umbilical donor cord blood is an excellent source of stem cells for transplantation of children with immune deficiency disorders. Benefits include rapid and reliable recovery of immune function, low risk of GvHD, and low viral transmission rate.

Transplantation of megadoses of purified haploidentical stem cells

Peripheral mobilized parental CD34+ progenitors were isolated and used for the hematopoietic reconstitution after a myeloablative therapy in 23 pediatric patients with various diseases. Fourteen donors were human leukocyte antigen (HLA) three-loci mismatches, 6 donors were two-loci and 3 donors were one-locus mismatches. For depletion of T-lymphocytes, a positive selection of the mobilized peripheral CD34+ progenitors using the method of magnetic-activated cell sorting (MACS) was used. The purity of the CD34+ cells after MACS-sorting was 98-99%, the average number of transplanted CD34+ cells was 14.2 x 10(6)/kg (range 5.4-3.9 x 10(6)/kg) and the average number of infused T-lymphocytes was 1.4 x 10(4)/kg. Due to this low T cell number, only a short-term or no prophylaxis of graft-versus-host disease (GVHD) was necessary and no GVHD was seen. A significant GVHD was only seen in patients after add-back of donor T-lymphocytes, which was performed in some patients for prevention of relapse or in patients who showed a transient mixed chimerism. Since the B lymphocyte contamination of the isolated CD34+ cells was low in the range of 0.2%, no Epstein-Barr virus (EBV)-associated lymphoproliferative syndrome was observed. A primary engraftment was seen in 18 patients. Nonengraftment and rejection occurred in three and two patients, respectively. In four of these 5 patients, a second transplant using purified CD34+ cells from the same donor after an immunological reconditioning regimen resulted in a complete and sustained hematopoietic reconstitution. The speed of the immunological recovery was dependent on the number of transplanted CD34+ cells and was more rapid if this number was > 20 x 10(6)/kg. Eleven of the 23 patients are alive and disease free with a median follow-up of 12 months (range 2-30). The main cause of death was relapse (7 patients), and only one fatal infection was seen. Our data suggest that the transplantation of megadoses of haploidentical CD34+ cells is a realistic therapeutic option for patients who otherwise have no suitable donor, and an alternative to the use of unrelated cord blood.

Hematopoietic stem-cell transplantation for the treatment of severe combined immunodeficiency

BACKGROUND

Since 1968 it has been known that bone marrow transplantation can ameliorate severe combined immunodeficiency, but data on the long-term efficacy of this treatment are limited. We prospectively studied immunologic function in 89 consecutive infants with severe combined immunodeficiency who received hematopoietic stem-cell transplants at Duke University Medical Center between May 1982 and September 1998.

METHODS

Serum immunoglobulin levels and lymphocyte phenotypes and function were assessed and genetic analyses performed according to standard methods. Bone marrow was depleted of T cells by agglutination with soybean lectin and by sheep-erythrocyte rosetting before transplantation.

RESULTS

Seventy-seven of the infants received T-cell-depleted, HLA-haploidentical parental marrow, and 12 received HLA-identical marrow from a related donor; 3 of the recipients of haploidentical marrow also received placental-blood transplants from unrelated donors. Except for two patients who received placental blood, none of the recipients received chemotherapy before transplantation or prophylaxis against graft-versus-host disease. Of the 89 infants, 72 (81 percent) were still alive 3 months to 16.5 years after transplantation, including all of the 12 who received HLA-identical marrow, 60 of the 77 (78 percent) who were given haploidentical marrow, and 2 of the 3 (67 percent) who received both haploidentical marrow and placental blood. T-cell function became normal within two weeks after transplantation in the patients who received unfractionated HLA-identical marrow but usually not until three to four months after transplantation in those who received T-cell-depleted marrow. At the time of the most recent evaluation, all but 4 of the 72 survivors had normal T-cell function, and all the T cells in their blood were of donor origin. B-cell function remained abnormal in many of the recipients of haploidentical marrow. In 26 children (5 recipients of HLA-identical marrow and 21 recipients of haploidentical marrow) between 2 percent and 100 percent of B cells were of donor origin. Forty-five of the 72 children were receiving intravenous immune globulin.

CONCLUSIONS

Transplantation of marrow from a related donor is a life-saving and life-sustaining treatment for patients with any type of severe combined immunodeficiency, even when there is no HLA-identical donor.

Virus-specific immunity after gene therapy in a murine model of severe combined immunodeficiency

Human severe combined immunodeficiency (SCID) can be caused by defects in Janus kinase 3 (JAK3)-dependent cytokine signaling pathways. As a result, patients are at high risk of life-threatening infection. A JAK3 -/- SCID mouse model for the human disease has been used to test whether transplant with retrovirally transduced bone marrow (BM) cells (JAK3 BMT) could restore immunity to an influenza A virus. The immune responses also were compared directly with those for mice transplanted with wild-type BM (+/+ BMT). After infection, approximately 90% of the JAK3 BMT or +/+ BMT mice survived, whereas all of the JAK3 -/- mice died within 29 days. Normal levels of influenza-specific IgG were present in plasma from JAK3 BMT mice at 14 days after respiratory challenge, indicating restoration of B cell function. Influenza-specific CD4(+) and CD8(+) T cells were detected in the spleen and lymph nodes, and virus-specific CD8(+) effectors localized to the lungs of the JAK3 BMT mice. The kinetics of the specific host response correlated with complete clearance of the virus within 2 weeks of the initial exposure. By contrast, the JAK3 -/- mice did not show any evidence of viral immunity and were unable to control this viral pneumonia. Retroviral-mediated JAK3 gene transfer thus restores diverse aspects of cellular and humoral immunity and has obvious potential for human autologous BMT.

Engraftment of Severe Combined Immune Deficient Mice Receiving Allogeneic Bone Marrow Via In Utero or Postnatal Transfer

Although in utero transplantation (IUT) has been shown to be effective in treating human severe combined immune deficiency (SCID), the relative merit of IUT as compared with postnatal bone marrow transplantation (BMT) for SCID is unknown. Therefore, comparative studies were undertaken in mice to determine the engraftment outcome in these two settings. Because T-cell depletion (TCD) reduces graft-versus-host disease (GVHD) severity but compromises alloengraftment, studies were performed with TCD or non-TCD BM and GVHD risk was assessed using a tissue scoring system and by the adoptive transfer of splenocytes from engrafted mice into secondary recipients. Non-SCID recipients received pre-BMT irradiation to simulate those circumstances in which conditioning is required for alloengraftment. IUT recipients of non-TCD and especially TCD BM cells in general had higher levels of donor T-cell and myeloid peripheral blood (PB) engraftment than nonconditioned SCID recipients. Increased TCD or non-TCD BM cell numbers in adult SCID recipients resulted in similar levels of PB engraftment as IUT recipients. However, under these conditions, mean GVHD scores were higher than in IUT recipients. The majority of adoptive transfer recipients of splenocytes from IUT recipients were GVHD-free, consistent with the in vitro evidence of tolerance to host alloantigens. Total body irradiation (TBI)-treated mice that had the highest engraftment had evidence of thymic damage as denoted by a higher proportion of thymic and splenic T cells with a memory phenotype as compared with IUT recipients. IUT mice had vigorous thymic reconstitution by 3 weeks of age. Our data indicate that IUT has a number of advantages as compared with postnatal BMT. Future studies examining the fine specificity of immunoreconstitution in IUT versus postnatal BMT are indicated.

Engraftment of Severe Combined Immune Deficient Mice Receiving Allogeneic Bone Marrow Via In Utero or Postnatal Transfer

Although in utero transplantation (IUT) has been shown to be effective in treating human severe combined immune deficiency (SCID), the relative merit of IUT as compared with postnatal bone marrow transplantation (BMT) for SCID is unknown. Therefore, comparative studies were undertaken in mice to determine the engraftment outcome in these two settings. Because T-cell depletion (TCD) reduces graft-versus-host disease (GVHD) severity but compromises alloengraftment, studies were performed with TCD or non-TCD BM and GVHD risk was assessed using a tissue scoring system and by the adoptive transfer of splenocytes from engrafted mice into secondary recipients. Non-SCID recipients received pre-BMT irradiation to simulate those circumstances in which conditioning is required for alloengraftment. IUT recipients of non-TCD and especially TCD BM cells in general had higher levels of donor T-cell and myeloid peripheral blood (PB) engraftment than nonconditioned SCID recipients. Increased TCD or non-TCD BM cell numbers in adult SCID recipients resulted in similar levels of PB engraftment as IUT recipients. However, under these conditions, mean GVHD scores were higher than in IUT recipients. The majority of adoptive transfer recipients of splenocytes from IUT recipients were GVHD-free, consistent with the in vitro evidence of tolerance to host alloantigens. Total body irradiation (TBI)-treated mice that had the highest engraftment had evidence of thymic damage as denoted by a higher proportion of thymic and splenic T cells with a memory phenotype as compared with IUT recipients. IUT mice had vigorous thymic reconstitution by 3 weeks of age. Our data indicate that IUT has a number of advantages as compared with postnatal BMT. Future studies examining the fine specificity of immunoreconstitution in IUT versus postnatal BMT are indicated.

Treatment of high-risk acute leukemia with T-cell-depleted stem cells from related donors with one fully mismatched HLA haplotype

BACKGROUND

In this study we tried to achieve successful transplantation in patients with acute leukemia with the use of hematopoietic stem cells from donors who shared only one HLA haplotype with the recipient (a "full-haplotype mismatch"). To prevent graft failure, large doses of T-cell-depleted hematopoietic stem cells were transplanted after a conditioning regimen of enhanced myeloablation and immunosuppression was administered to the recipient.

METHODS

Forty-three patients with high-risk acute leukemia who were scheduled for transplantation received total-body irradiation, thiotepa, fludarabine, and antithymocyte globulin. The graft consisted of peripheral-blood progenitor cells that had been mobilized in the donor with recombinant granulocyte colony-stimulating factor and also, in 28 cases, bone marrow. Bone marrow from the donor was depleted of T lymphocytes by processing with soybean agglutinin and E-rosetting. T-cell depletion of peripheral-blood mononuclear cells was achieved by E-rosetting followed by positive selection of CD34+ cells. No post-transplantation prophylaxis against graft-versus-host disease (GVHD) was administered.

RESULTS

In all the patients, full donor-type engraftment was achieved. In none of the patients who could be evaluated did acute or chronic GVHD develop. Regimen-related toxicity was minimal. Eleven of the 23 patients with acute lymphoblastic leukemia had a relapse, as did 2 of the 20 patients with acute myeloid leukemia. Transplantation-related mortality was 40 percent. After a median follow-up of 18 months (range, 8 to 30), 12 of the 43 patients were alive and free of disease. All surviving patients had a good quality of life.

CONCLUSIONS

The main limitations of transplantation of bone marrow from donors who are matched with the recipient for only one HLA haplotype GVHD and graft failure - can be overcome. Since most patients have a relative with one haplotype mismatch, advances in this method will increase the availability of hematopoietic-cell transplantation as curative therapy for acute leukemia.

Molecular and biochemical characterization of JAK3 deficiency in a patient with severe combined immunodeficiency over 20 years after bone marrow transplantation: implications for treatment

Severe combined immunodeficiency (SCID) comprises a heterogenous group of disorders that are fatal unless treated by bone marrow transplantation (BMT). The most common form of SCID (T-B+ SCID) is due to mutations of either the common gamma chain (gammac) or of gammac-coupled JAK3 kinase. We report an unusual JAK3 defect in a female who was successfully treated > 20 years ago with a BMT using her HLA-identical father as the donor. Persistence of genetically and biochemically defective autologous B cells, associated with reconstitution of cellular and humoral immunity, suggests that integrity of the gammac-JAK3 signalling pathway is not strictly required for immunoglobulin production.

Long-term T cell immune reconstitution in 2 SCID patients after BMT

To evaluate the long-term reconstitution of the T cell immune repertoire in recipients of an allogeneic Bone Marrow Transplantation (allo-BMT), we have analyzed the T cell receptor (TCR) repertoire in the periphery and the T cell response against tetanus toxoid in two T- B+ Severe Combined Immunodeficiency Disease (SCID) patients more than 11 years after HLA haplo-identical allo-BMT. Our studies demonstrate that in the periphery of allo-BMT recipients, on the basis of TCR V-gene segment usage, the T cell immune repertoire long after allo-BMT is diverse, as is that of the donor. However, when donor and allo-BMT recipient were compared, differences were noted in the TCR Complementarity Determining Region 3 (CDR3) size distributions and in the T cell response against tetanus toxoid. In particular, the tetanus toxoid specific T cell clones differed in their use of HLA restriction elements, and expressed different T cell receptors. Moreover, we have uncovered donor-type tetanus toxoid specific T cell clones which were established from allo-BMT recipient derived peripheral blood lymphocytes and were found to be restricted by the non-shared recipient allele. This observation suggests a role for recipient-mediated T cell selection processes, in the thymus or at extra-thymic sites.

Pulmonary diseases in children with severe combined immune deficiency and DiGeorge syndrome

Pulmonary disease is a common presenting feature and complication of T-cell immunodeficiency. We retrospectively reviewed 15 children with severe combined immune deficiency (SCID) and 19 children with DiGeorge syndrome at the time of their first presentation to the Royal Children's Hospital in the 15-year period from 1981 to 1995. In children with SCID, pulmonary disease was a common (67%) presenting feature and the organisms identified were Pneumocystis carinii (PCP) (n = 7), bacteria (n = 4), viruses (n = 3), and a fungus (n = 1). Late pulmonary complications included lower respiratory tract infections, bronchiolitis obliterans, and lymphointerstitial pneumonitis. Pulmonary infections were common (17 occasions) and the organisms identified were bacteria (n = 7), viruses (n = 6), fungi (n = 3), and Mycobacterium tuberculosis (n = 1). Pulmonary complications were responsible for 5 of 9 deaths. PCP was not identified as a late complication in any child, presumably as a result of effective prophylactic therapy. Although pulmonary disease was not a major presenting feature in children with DiGeorge syndrome, pulmonary complications were common. These included recurrent bacterial and viral infections and bronchomalacia, which complicated management and predisposed to morbidity and mortality, even in those without a T-cell defect. We conclude that pulmonary disease is a common manifestation in children with SCID and DiGeorge syndrome.

Full Immunologic Reconstitution Following Nonconditioned Bone Marrow Transplantation for Canine X-Linked Severe Combined Immunodeficiency

Bone marrow transplantation in human X-linked severe combined immunodeficiency (XSCID) without pretransplant conditioning results in engraftment of donor T cells and reconstitution of T-cell function but engraftment of few, if any, donor B cells and poor reconstitution of humoral immune function. Since bone marrow transplantation remains the most effective treatment of XSCID patients, better strategies are necessary to achieve optimum long-term results. Canine XSCID, like human XSCID, is due to mutations in the common γ chain (γc) gene and has clinical and immunologic features identical to those of human XSCID, making it a true homolog of the human disease. We have successfully performed bone marrow transplantation in three XSCID dogs without pretransplant conditioning, using untreated bone marrow cells from mixed lymphocyte culture–nonreactive normal littermates. Unlike the experience in human XSCID patients, all three dogs engrafted both donor B and T cells and attained full reconstitution of immunologic function. Normal percentages of T cells and T-cell mitogenic responses were attained by 3 months posttransplant. CD3+ T cells after transplantation expressed the CD45RA isoform indicating that the cells were recent thymic emigrants derived from immature progenitors. Serum IgG levels were within normal range by 5 months posttransplant. Immunization with the T-dependent antigen, bacteriophage φX174, demonstrated normal antibody titers, immunologic memory, and class-switching. Polymerase chain reaction (PCR) analysis of the γc locus showed that 100% of circulating T cells and 30% to 50% of circulating B cells were donor-derived. None of the dogs developed clinically evident graft-versus-host disease (GVHD). Thus, canine XSCID provides a model to determine the optimal conditions for bone marrow transplantation in human patients, and to develop and test strategies for somatic gene therapy.

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.

A girl with diabetes and severe combined immunodeficiency from adenosine deaminase deficiency

We present a girl with severe combined immunodeficiency (SCID) from adenosine deaminase (ADA) deficiency who developed insulin dependent diabetes mellitus (IDDM). This combination of features has not been previously reported. Because HLA typing (DQbeta-57 Asp/Asp and DQalpha-52 Ser/Ser) showed no alleles usually associated with IDDM, and ICA were repeatedly negative even after treatment with PEG-ADA and gene transplant, hypotheses on the pathogenesis of diabetes mellitus in this patient are discussed.

In vitro correction of JAK3-deficient severe combined immunodeficiency by retroviral-mediated gene transduction

Mutations affecting the expression of the Janus family kinase JAK3 were recently shown to be responsible for autosomal recessive severe combined immunodeficiency (SCID). JAK3-deficient patients present with a clinical phenotype virtually indistinguishable from boys affected by X-linked SCID, a disease caused by genetic defects of the common gamma chain (gamma c) that is a shared component of the receptors for IL-2, IL-4, IL-7, IL-9, and IL-15. The specific interaction of JAK3 and gamma c represents the biochemical basis for the similarities between these two immunodeficiencies. Both forms of SCID are characterized by recurrent, severe infections leading to death in infancy unless successfully treated by allogeneic bone marrow transplantation. Because of the potentially lethal complications associated with allogeneic bone marrow transplantation and the frequent lack of suitable marrow donors, the development of alternative forms of therapy is highly desirable. To this end, we investigated a retroviral-mediated gene correction approach for JAK3-deficiency. A vector carrying a copy of JAK3 cDNA was constructed and used to transduce B cell lines derived from patients with JAK3-deficient SCID. We demonstrate restoration of JAK3 expression and phosphorylation upon IL-2 and IL-4 stimulation. Furthermore, patients' cells transduced with JAK3 acquired the ability to proliferate normally in response to IL-2. These data indicate that the biological defects of JAK3-deficient cells can be efficiently corrected in vitro by retroviral-mediated gene transfer, thus providing the basis for future investigation of gene therapy as treatment for JAK3-deficient SCID.

Bone marrow transplantation in immunodeficiency diseases

Bone marrow transplantation (BMT) has become the treatment of choice in an increasing number of primary immunodeficiency disorders. In many of these otherwise lethal genetic diseases, BMT can completely reverse the immunological abnormality and patients may be permanently cured. In this review, current approaches in the application of this treatment and results obtained in various entities of primary immunodeficiencies are presented. A significant prognostic factor for the outcome is the clinical condition of the patient at the time of BMT, and prompt recognition of these rare disorders remains an important prognostic factor for BMT.

Toxicities of total-body irradiation for pediatric bone marrow transplantation

PURPOSE

To determine the acute and late effects, including cognitive function, of total body irradiation (TBI) and chemotherapy for bone transplant (BMT) in children with immunodeficiency or hematologic disorders.

METHODS AND MATERIALS

At UCSF, 15 children with immunodeficiency disorders and 58 children with leukemia received chemoradiotherapy between July 1982 and November 1993 and were evaluated for toxicity. Patients with severe combined immunodeficiency disorder (SCID) received 7 Gy TBI while leukemia patients received 12 Gy TBI.

RESULTS

Eight immunodeficient patients (53%) are alive at 4 months to 11 years posttransplant. Acute toxicity was limited and treatment well tolerated. Most patients developed mild nausea and vomiting, skin rash, or erythema. Transient fever/chills, oral mucositis, and alopecia were noted in approximately 50% of patients. Seventy-three percent of all patients demonstrated acute liver dysfunction, but only four (27%) developed veno-occlusive disease. All children had decreased growth velocity but normal growth hormone levels. Other endocrinologic evaluations including adrenocorticotropic hormone (ACTH), cortisol, and thyroid hormones were normal. Only one evaluable girl had delayed puberty with late onset of secondary sexual characteristics. Neuropsychological testing demonstrated an intelligence quotient (IQ) reduction between the baseline and 1 year post-BMT, with some recovery at 3 years. Only one patient developed a clinically significant cataract. Thirteen percent of patients had chronic interstitial lung disease. Four children developed exostosis. Only 1 of the 15 children developed a second malignancy (acute myelogenous leukemia) at age 5, 51 months posttransplant for SCID. For patients with leukemia, similar toxicities were observed. Twenty-nine percent disease-free survival was noted with a mean follow-up of 4.7 years. Twenty-two percent had chronic interstitial lung disease and two patients were diagnosed with cataracts. Graft-vs.-host-disease (GVHD), pubertal development arrest, and delayed puberty were seen. One child developed papillary thyroid carcinoma, 49 months post-BMT. Similar neuropsychological testing decrements were also observed.

CONCLUSION

Our experience suggests that intensive chemoradiotherapy, even at a young age, does not cause severe, acute, or late toxicities but does result in a small IQ decrement and the risk of secondary malignancy in children with long-term follow-up.

PEG-ADA replacement therapy for adenosine deaminase deficiency: an update after 8.5 years

Polyethylene glycol-modified adenosine deaminase (PEG-ADA) has now been used for 8.5 years as enzyme replacement therapy for immunodeficiency due to ADA deficiency. PEG-ADA restores a metabolic environment necessary for recovery of immune function. In most cases, the level of function achieved has been sufficient to protect against opportunistic and life-threatening infections. To date, mortality and morbidity with PEG-ADA have been less than for haploidentical bone marrow transplantation. As a true "orphan drug" used to treat a very small patient population, the cost per patient of PEG-ADA is very high, but it has been well tolerated, free of adverse reactions, and effective as an alternative for patients who lack an HLA-identical marrow donor, but are considered too ill to undergo haploidentical marrow transplantation. Concomitant treatment with PEG-ADA has also permitted investigation of gene therapy to be carried out safely.

A single nucleotide insertion in the canine interleukin-2 receptor gamma chain results in X-linked severe combined immunodeficiency disease

The immunologic and genetic analysis of a 14-week-old-male cardigan Welsh corgi puppy that presented with failure to thrive, diarrhea, and intermittent vomiting are described. The lack of palpable lymph nodes, the premature death of a male sibling, and similar clinical signs in a male cousin suggested that a primary immunodeficiency disease might be responsible for his poor clinical condition. Quantitation of serum immunoglobulins revealed low concentrations of IgG and undetectable IgA, yet normal concentrations of IgM. A complete blood cell count showed a slight anemia and lymphopenia. Although the peripheral blood contained a normal percentage of T cells, with an increased CD4:CD8 ratio, they were unable to proliferate in response to phytohemagglutinin (PHA) and/or interleukin 2 (IL-2). Furthermore, following PHA activation, the peripheral blood lymphocytes (PBL) demonstrated a nearly complete lack of IL-2 binding. All of these laboratory findings were identical with our previous findings from dogs with X-linked severe combined immunodeficiency (XSCID) that is due to a mutation in their IL-2 receptor gamma (IL-2R gamma) chain. Examination of the corgi's IL-2R gamma cDNA revealed an insertion of a cytosine following nucleotide 582, resulting in a premature stop codon prior to the transmembrane domain. The insertion also created an EcoO109 restriction enzyme site that enabled us to detect the mutation in the patient's genomic DNA. This new mutation in the IL-2R gamma chain discovered in a cardigan Welsh corgi puppy results in XSCID with similar immunologic abnormalities as observed in dogs with the same disease resulting from a different IL-2R gamma chain mutation.

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.

PEG-ADA: an alternative to haploidentical bone marrow transplantation and an adjunct to gene therapy for adenosine deaminase deficiency

PEG-ADA is a long-circulating form of adenosine deaminase (ADA) that has been in use for > 8 years as replacement therapy for severe combined immunodeficiency disease due to ADA deficiency. Treatment with PEG-ADA almost completely corrects metabolic abnormalities, allowing the recovery of a variable degree of immune function. Although not normal, the level of function achieved has in most cases been sufficient to protect against opportunistic and life-threatening infections. PEG-ADA has been used as an alternative for patients who lack an HLA-identical bone marrow donor, but are judged to be at too high a risk for undergoing HLA-haploidentical marrow transplantation. To date, mortality and morbidity with PEG-ADA have been less than for the latter procedure. PEG-ADA has also been an important adjunct to attempts to develop somatic cell gene therapy for ADA deficiency, although its continued use poses a problem for evaluation of the benefit of gene therapy. As a true "orphan drug" developed to treat a very small patient population, the cost per patient of PEG-ADA is very high.

Breakthroughs in the understanding and therapy of primary immunodeficiency

In the 40 years since Ogden Bruton discovered agammaglobulinemia, more than 50 additional immunodeficiency syndromes have been described. Until recently, there was little insight into the fundamental problems underlying a majority of these conditions. Recently, however, the molecular bases of three X-linked immunodeficiency disorders have been reported. These include X-linked immunodeficiency with hyper IgM, X-linked agammaglobulinemia, and X-linked severe combined immunodeficiency. These remarkable accomplishments have been made possible through a combination of new knowledge of molecular signaling mechanisms between and within cells of the immune system and greatly improved approaches to disease loci mapping within the human genome. Improvements in the therapy of immunodeficiency diseases have been impressive, and the development of generally safe and effective intravenous immunoglobulin preparations and T cell depletion techniques that permit the use of non-HLA-identical bone marrow donors have been the most important advances over the past 14 years. The identification and cloning of the genes for several of the primary immunodeficiency diseases have obvious implications for potential future somatic cell gene therapy for these patients. The rapidity of these advances suggests that soon there will be many more to come.

An influence diagram for assessing GVHD prophylaxis after bone marrow transplantation in children

Graft-versus-host disease (GVHD) represents one of the major complications of allogeneic bone marrow transplantation (BMT). Nevertheless, the occurrence of mild GVHD could be desirable in high-risk leukemic patients, due to a relapse-preventing effect known as the graft-versus-leukemia (GVL) effect. Given that different prophylactic interventions are available to prevent GVHD development, the decision problem consists in assessing both type and dosage of the drugs in order to avoid or induce GVHD, according to the specific patient's condition. The decision problem can be represented and solved by using an influence diagram. The choice of this formalism allows using new available methods for building and updating the model of the decision problem. The qualitative structure of the model and the conditional probabilities were first derived by combining literature results with a medical expert's judgement. More specifically, probabilities were initially assigned as ranges rather than as point values. Then, conditional probabilities were updated, by using a learning algorithm, as new cases became available. The authors analyzed 50 cases of pediatric patients affected by either malignant or nonmalignant diseases, undergoing BMT and receiving GVHD prophylaxis. They used the first 25 cases to adjust the initially assigned conditional probabilities, then checked the model obtained on the remaining patients. The overall performance for GVHD prediction was about 80%.

Acute monocytic leukemia in a dog with X-linked severe combined immunodeficiency

We describe the occurrence of acute monocytic leukemia in a dog with X-linked severe combined immunodeficiency (XSCID) that had been raised in a gnotobiotic environment for 20 months. This case represents the first reported instance of malignancy in canine XSCID, the first case of acute monocytic leukemia in any species with severe combined immunodeficiency, and the first documented malignancy in any species with XSCID that was not associated with immunotherapy.

Early diagnosis of severe combined immunodeficiency syndrome

Infants with severe combined immunodeficiency syndrome (SCIDS) have a greatly improved prognosis if diagnosed and treated before they develop overwhelming infection. Clinical and laboratory data on 45 patients with SCIDS were retrospectively reviewed to assess the value of absolute lymphocyte counts in making an early diagnosis. Ninety infants matched for age, sex, and presenting symptoms were used as controls. Thirteen (29%) infants with SCIDS were diagnosed at birth as previous siblings had been affected; 32 (71%) were diagnosed after the development of symptoms. Eighteen (56%) of these remained undiagnosed until after 6 months of age. The first symptoms occurred at a median of 5 weeks (range 1 day to 8 months) and the first admission to hospital was at 4 months (range 1 week to 16 months). Symptoms included respiratory infection (91%), vomiting and diarrhoea (81%), failure to thrive (88%), candidiasis (50%), and skin lesions (28%). The mean lymphocyte count was 1.71 x 10(9)/l compared with 7.2 x 10(9)/l in controls. Excluding one child with Omenn's syndrome (lymphocyte count 23.3 x 10(9)/l, all symptomatic infants with SCIDS had lymphocyte counts less than 2.8 x 10(9)/l at presentation. The median delay between the first abnormal lymphocyte count and diagnosis was seven weeks (range one day to 13 months). Twenty eight (88%) of 32 infants would have been diagnosed before 6 months of age if investigated after the first low lymphocyte count. These data indicate that low lymphocyte counts are predictive of SCIDS. Paediatricians are urged to pay attention to the absolute lymphocyte counts in all infants in whom a full blood count is performed. Those with lymphocyte counts persistently less than 2.8 x 10(9)l should be investigated for SCIDS.

Anti-tetanus toxoid antibody production after mismatched T cell-depleted bone marrow transplantation

We explored B-cell function after tetanus toxoid (TT) immunization in 12 children with severe combined immunodeficiency disease or leukemia who were long-term survivors of an HLA-matched sibling or haplocompatible T cell-depleted parental bone marrow transplant (BMT), 10 of their healthy donors, and 13 normal controls. Specific in vivo and in vitro anti-TT antibody (Ab) production were measured by ELISA. We studied donors' and recipients' peripheral blood mononuclear cells (PBMC) and mixed E- (non-T cells) and E+ cells (T cells) spontaneously and after stimulation by TT in the absence or presence of interleukin-2 (IL-2), IL-4, and IL-6. Five of the 12 patients and all donors and controls responded with in vivo anti-TT Ab. In vitro anti-TT Ab production correlated with the in vivo response. All seven of the nonresponders were either fully engrafted or mixed chimeras (donor T cells but autologous B cells and monocytes). We could not identify a T-cell defect in four of the five nonresponders who were tested. In contrast, E- cells from three of three responders cooperated with fresh donor E+ cells even when they shared only one HLA haplotype. In three of seven nonresponders, in vitro anti-TT Ab production was restored after the addition of IL-4 or IL-6 but not IL-2. Our results suggest that the humoral immunodeficiency that exists post mismatched T cell-depleted BMT is either a B-cell, a monocyte, or a B-cell/T-cell cooperation defect which, in some patients, may be correctible with the addition of a cytokine. Also, it is not necessary to engraft donor B cells to achieve normal antibody responses and the ability to respond does not appear to correlate with pretransplant chemotherapy.

Use of recombinant human granulocyte-macrophage colony stimulating factor in an infant with reticular dysgenesis

We present the case of a 2-month-old infant with reticular dysgenesis who was treated with recombinant granulocyte-macrophage colony stimulating factor with the aim of stimulating granulopoiesis while awaiting bone marrow transplant.

High levels of interleukin 10 production in vivo are associated with tolerance in SCID patients transplanted with HLA mismatched hematopoietic stem cells

Transplantation of HLA mismatched hematopoietic stem cells in patients with severe combined immunodeficiency (SCID) can result in a selective engraftment of T cells of donor origin with complete immunologic reconstitution and in vivo tolerance. The latter may occur in the absence of clonal deletion of donor T lymphocytes able to recognize the host HLA antigens. The activity of these host-reactive T cells is suppressed in vivo, since no graft-vs. -host disease is observed in these human chimeras. Here it is shown that the CD4+ host-reactive T cell clones isolated from a SCID patient transplanted with fetal liver stem cells produce unusually high quantities of interleukin 10 (IL-10) and very low amounts of IL-2 after antigen-specific stimulation in vitro. The specific proliferative responses of the host-reactive T cell clones were considerably enhanced in the presence of neutralizing concentrations of an anti-IL-10 monoclonal antibody, suggesting that high levels of endogenous IL-10 suppress the activity of these cells. These in vitro data correlate with observations made in vivo. Semi-quantitative polymerase chain reaction analysis carried out on freshly isolated peripheral blood mononuclear cells (PBMC) of the patient indicated that the levels of IL-10 messenger RNA (mRNA) expression were strongly enhanced, whereas IL-2 mRNA expression was much lower than that in PBMC of healthy donors. In vivo IL-10 mRNA expression was not only high in the T cells, but also in the non-T cell fraction, indicating that host cells also contributed to the high levels of IL-10 in vivo. Patient-derived monocytes were found to be major IL-10 producers. Although no circulating IL-10 could be detected, freshly isolated monocytes of the patient showed a reduced expression of class II HLA antigens. However, their capacity to stimulate T cells of normal donors in primary mixed lymphocyte cultures was within the normal range. Interestingly, similar high in vivo IL-10 mRNA expressions in the T and non-T cell compartment were also observed in three SCID patients transplanted with fetal liver stem cells and in four SCID patients transplanted with T cell-depleted haploidentical bone marrow stem cells. Taken together, these data indicate that high endogenous IL-10 production is a general phenomenon in SCID patients in whom allogenic stem cell transplantation results in immunologic reconstitution and induction of tolerance. Both donor T cells and host accessory cells contribute to these high levels of IL-10, which would suppress the activity of host-reactive T cell in vivo.

HLA non-identical T-cell-depleted bone marrow transplantation for primary immunodeficiency diseases

BACKGROUND

Bone marrow transplantation (BMT) is usually the only procedure offering cure for children with life-threatening immune deficiency disorders, but compatible sibling donors are frequently unavailable.

AIMS AND METHODS

To examine the outcome of HLA non-identical T-cell-depleted BMT carried out between April 1985 and May 1992 in 11 patients with primary immunodeficiency diseases and to seek prognostic factors.

RESULTS

Eight patients achieved sustained engraftment, one after a second BMT. One further patient engrafted transiently, but rejected the graft five months later. Acute graft-versus-host disease (GVHD) grade II was seen in one and chronic GVHD was seen in three children. Seven patients survived beyond six months, six with donor T cell and five with donor B cell engraftment. At present, five patients (46%) are alive with immune reconstitution at a median follow-up of 14 months (range 6 to 78 months). The major factor associated with outcome was the presence of any infection within one week of BMT (p = 0.01). The presence of lung infection also tended to be a poor prognostic factor (p = 0.06) but did not reach significance, presumably because of the small sample size. HLA non-identical (parental) T-cell depleted BMT plays an important role in the cure of children with immunodeficiencies who do not have an identical sibling donor. Survival can be further improved if the diagnosis of immunodeficiency disease is made early and BMT undertaken before significant infections occur.

CONCLUSIONS

The availability of T-cell depleted haploidentical parental bone marrow transplant can be anticipated to improve outcome significantly for children with severe immunodeficiency, especially when diagnosed early.

Bone marrow transplantation today

Today, bone marrow transplantation (BMT) is an established therapy. This statement is best verified by the number of BMTs performed. Between January 1990 and December 1992, 172 European teams in 26 countries carried out a total of 14,334 transplants. There were 6642 allogeneic transplants: 5513 BMT from an HLA-identical sibling donor, 370 from a non-identical family member, 88 from an identical twin donor and 671 from an unrelated volunteer donor. There were 7692 autologous transplants: 6577 autologous bone marrow, 777 peripheral-blood stem-cell and 338 combined bone-marrow and peripheral-blood stem-cell transplants. Indications were: leukaemias in 52% (7479), lymphoproliferative disorders in 29% (4125), solid tumours in 11% (1540), aplastic anaemia and thalassaemia in 3% (487) and inborn errors an miscellaneous disorders in the remaining 5% (703). The results of these transplants are not yet known. From previous analyses it can be expected that more than 50% of patients will be alive and well 10 years after BMT. The main factors influencing outcome are known; they depend on type, sub-type, stage of disease at time of transplant, the time from diagnosis to transplant and the conditioning regimen for all transplants. For allogeneic BMT, donor source, donor and recipient age, sex, donor/recipient sex combination, donor and recipient viral status, graft-versus-host disease prevention method and region are additional factors. Knowledge of these factors enables us today to estimate the potential risk and adjust the therapy for an individual patient.

Major histocompatibility complex class II deficiency: clinical manifestations, immunologic features, and outcome

Major histocompatibility complex class II deficiency (bare lymphocyte syndrome) is a rare primary immunodeficiency disorder characterized by profound defects in human leukocyte antigen class II expression, inconsistent and incomplete expression of human leukocyte antigen class I molecules, and a complete lack of cellular and humoral immune responses to foreign antigens. To define the clinical and immunologic characteristics, outcome, and natural history of major histocompatibility complex class II deficiency, we retrospectively analyzed 30 consecutive patients. Clinical onset occurred in the first year of life, usually involving recurrent bronchopulmonary infections and chronic diarrhea. The clinical course was complicated by viral meningoencephalitis, hepatitis, cholangitis, and various autoimmune phenomena. Prognosis was very poor: the mean age at the time of death was 4 years. The main cause of death was overwhelming viral infection. Recent advances in bone marrow transplantation have raised hopes of curative treatment: 6 of 14 patients who underwent bone marrow transplantation were cured. Long-term survival after human leukocyte antigen-identical and haploidentical bone marrow transplantation seemed to depend primarily on the presence of preexisting viral infections.