Purification and partial characterization of a human hematopoietic precursor population

This study reports the development of an assay, the Pre-colony-forming unit (CFU) assay, which detects human hematopoietic precursors. The Pre-CFU assay is based on the observation that precursors to CFU-granulocyte-macrophage (CFU-GM) that are undetectable in clonogenic assays differentiate into CFU-GM preferentially following treatment in suspension culture with recombinant human interleukin-1 alpha (rhIL-1 alpha) combined with rhIL-3. Using the Pre-CFU assay, hematopoietic precursors were detected in human bone marrow depleted of CFU-GM progenitors and differentiated hematopoietic elements via 4-hydroperoxycyclophosphamide treatment coupled with selection for CD34+ cells (4-HCresistant/CD34+ marrow). Additionally, the Pre-CFU assay detected recovery of hematopoiesis substantially earlier than the CFU-GM assay in primates following myeloablation with 5-fluorouracil. The Pre-CFU assay was used to asses purification of a phenotypically defined hematopoietic precursor population, the lin-CD34+ population. The lin-CD34+ population lacks detectable surface markers for T-cell, B-cell, natural killer cell, and myeloid lineage, possesses the CD34 antigen, is devoid of CFU-GM progenitors, and yields Pre-CFU assay values comparable with 4-HCresistant/CD34+ marrow. Using a combination of phenotypic analysis and Pre-CFU assay analysis, the action of rhIL-1 alpha plus rhIL-3 treatment on lin-CD34+ cells was further characterized. The data indicate that rhIL-1 alpha plus rhIL-3 treatment induces proliferation and differentiation of early hematopoietic precursors into progenitors and terminally differentiated cells, without inducing a significant expansion of the precursor population itself.

Myeloablative combination chemotherapy without total body irradiation for neuroblastoma

Myeloablative treatment intensification in 25 patients diagnosed when older than 12 months of age with stage IV neuroblastoma included sequential delivery of cisplatin 120 mg/m2 x 1, hyperfractionated radiation (2,100 cGy) to the primary site and adjacent lymph nodes, carmustine (BCNU) 200 mg/m2 x 1, melphalan 60 mg/m2/d x 3 (n = 13) or thiotepa 300 mg/m2/d x 3. (n = 12), and etoposide (VP 16) 300 mg/m2/d x 3. Seventy-two hours after the last dose of VP 16, histologically tumor-free and 4-hydroperoxycyclophosphamide (4-HC; 100 mumol/L)-purged autologous bone marrow (ABMT) was infused. Acute toxicities included grade 3 to 4 oral mucositis, grade 1 to 2 diarrhea, and fevers. No patient required infusion of unpurged reserve autografts. At ABMT, 16 patients (group I) were progression-free 6.5 months to 14 months (median, 9 months) from diagnosis: seven remain progression-free 20 months to 46 months (median, 39 months) off therapy, six relapsed 4 months to 17 months post-ABMT, and three died of toxicity (candidiasis, metabolic derangement, and venoocclusive disease [VOD]). The event-free survival of group I patients is 44% at 24 months post-ABMT. Nine patients (group II) were in second remission at ABMT, including three who had relapsed after other transplant procedures: two are progression-free 24 months and 41 months off therapy, four relapsed 3 months to 12 months post-ABMT, and three died of toxicity (aspergillosis, hemorrhagic cystitis, VOD). Only one of 10 relapses involved a primary site, suggesting a beneficial effect of local radiation. In terms of survival or toxicity, an advantage for melphalan or thiotepa was not evident. Regimens such as this may prolong the survival of selected patients with poor-risk neuroblastoma, but concerns over late relapses and toxicity mandate continuing efforts to devise alternative, less risky, and more clearly beneficial approaches for definitive ablation of neuroblastoma.

B-cell differentiation following autologous, conventional, or T-cell depleted bone marrow transplantation: a recapitulation of normal B-cell ontogeny

The circulating lymphocytes of 88 consecutive patients following autologous, conventional, or T-cell depleted bone marrow transplantation were serially analyzed for B-cell surface antigen expression and function. In the majority of patients, except for those who developed chronic graft-versus-host disease, the number of circulating CD20+ B cell normalized by the fourth posttransplant month. The earliest detectable B cells normally expressed HLA-DR, CD19, surface immunoglobulin (slg), CD21, Leu-8, and lacked expression of CD10 (CALLA). In addition, the circulating B cells expressed CD1c, CD38, CD5, and CD23 for the first year following transplant, antigens that are normally expressed on a small percentage of circulating B cells in normal adults, but highly expressed on cord blood B cells. Similar to cord blood B cells, patient B cells isolated during the first year following transplant, proliferated normally to Staphylococcus aureus Cowan strain I (SAC), and produced IgM, but minimal or no IgG when stimulated with pokeweed mitogen and SAC, unlike normal adult B cells that produce both. The similar phenotype and function of posttransplant and cord blood B cells, and their similar rate of decline in patients and normal children adds further evidence to support the hypothesis that B-cell differentiation posttransplant is recapitulating normal B-cell ontogeny.

Dose-intensive use of cyclophosphamide in ablation of neuroblastoma

A dose-intensive, cyclophosphamide (CPM)-based chemotherapy regimen was tested in 22 children with newly diagnosed metastatic or refractory neuroblastoma. The N5 protocol consisted of four courses of CPM (140 mg/kg over 2 days), doxorubicin (45 mg/m2 over 3 days), and vincristine (0.05 mg/kg/d on days 1, 2, and 9) (CAV regimen), followed by three courses of cisplatin (40 mg/m2/d) and VP16 (150 mg/m2/d) for 3 days (PVP regimen). Courses started when the neutrophil count was 500/microliters or greater and the platelet count was greater than 100,000/microliters; most courses began by day 21. Extramedullary toxicities were mild. All patients had Grade 3 to 4 myelosuppression, yet bone marrow harvested after the N5 protocol engrafted in 11 of 11 patients whose post-N5 treatments required autologous bone marrow transplantation (ABMT). Among 14 previously untreated patients, the N5 plus surgery achieved 9 complete remissions (CR) or very good partial remissions (VGPR) and 3 partial remissions (PR). An additional patient achieved CR with CAV, but experienced a recurrence in the bone marrow after PVP. The sole previously untreated patient whose bone marrow disease did not resolve received courses of the N5 at prolonged intervals (for nonmedical reasons). Among eight patients with progressive (six patients) or refractory (two patients) disease while on other, lower dose regimens, the N5 plus surgery achieved five CR/VGPR, two PR, and one minor response (MR). In conclusion, dose-intensive use of CPM has tolerable toxicity and does not preclude autografting; when administered in conjunction with other cytotoxic agents, it is highly effective against metastatic neuroblastoma and causes regressions of disease resistant to less intensive regimens. This approach plus surgery reliably achieves a minimal disease state that may be amenable to definitive ablation with relatively nontoxic therapies.

Cytotoxic and proliferative T-cell clones with antidonor reactivity from a patient transplanted for severe combined immunodeficiency disease

Patients who have become split lymphoid chimeras (T cells of donor origin, B cells and monocytes of host origin) following transplantation of HLA-haploidentical marrow for the treatment of severe combined immunodeficiency disease provide a unique model for the study of tolerance. One such patient, UPN 345, was transplanted with maternal marrow and was found to have antidonor proliferative reactivity without detectable donor-directed cytotoxicity when tested at 18, 23, and 66 mos following bone marrow transplantation. In bulk culture, the proliferation to donor cells could be blocked by monoclonal antibodies to HLA-DR and -DQ. Nine clones with antidonor reactivity were established by limiting dilution techniques from a mixed lymphocyte culture between engrafted T cells and irradiated donor E rosette-negative cells. All of the clones were of maternal donor origin, and all were CD3+CD4+CD8-. The clones were tested for proliferative and cytotoxic activity toward donor, host, and paternal B-lymphoblastoid cell lines (B-LCL). Six clones proliferated strongly to maternal B-LCL but not to host B-LCL. Six clones were found to exclusively lyse maternal B-LCL. Four of the clones had both antidonor cytotoxic and antidonor proliferative reactivity. Monoclonal antibody blocking studies were performed on five of the six clones with cytotoxic activity. The antidonor cytotoxicity was not inhibited by monoclonal antibodies to class I determinants; however, three clones were inhibited in the presence of monoclonal antibody to DR, one clone was inhibited by anti-DQ monoclonal antibody, and one clone was inhibited by anti-DP monoclonal antibody. The cytotoxicity of all five clones was inhibited by monoclonal antibody to CD4. These data indicate that antidonor reactivity may also include a cytotoxic component which is not apparent in bulk cultures and which, based on our limiting dilution studies, is probably controlled by regulatory cells. Both the antidonor cytotoxicity and the antidonor proliferation appear to be directed primarily toward donor HLA class II antigens that are not shared with the patient.

Evidence that appearance of thymulin in plasma follows lymphoid chimerism and precedes development of immunity in patients with lethal combined immunodeficiency transplanted with T cell-depleted haploidentical marrow

Thymulin, a peptide secreted by human thymic epithelial cells, circulates in peripheral blood. Levels of plasma thymulin (FTS-Zn) activity were analyzed in 21 patients with lethal combined immunodeficiency disorders who were treated with transplantation of HLA-haplotype-mismatched parental bone marrow depleted of T cells by differential agglutination with soybean agglutinin and E-rosetting (SBA-E-BMT). Among these 21 infants, 15 were patients with severe combined immunodeficiency (SCID) and 6 had combined immunodeficiency (CID) with Omenn's syndrome or CID with T cell predominance (CIDTP). In contrast to normal infants who possess high levels of plasma thymulin activity, 20 of the 21 patients demonstrated undetectable or low plasma thymulin levels for their age at admission prior to transplantation. Following SBA-E-BMT, however, thymulin became detectable in the plasma of 17 of 18 evaluable patients and reached normal or near-normal levels between 21 and 125 days posttransplant. In patients in whom the timing of engraftment could be established by emergence of donor lymphocytes, thymulin appeared in the plasma at approximately the same time as lymphoid chimerism was detected, and in all patients who were engrafted and immunologically reconstituted, the increment in thymulin levels preceded development of immune functions. These studies support the concept that normal marrow-derived cells in the graft can provide a stimulus necessary for induction of thymic epithelial secretory function in patients with thymic dysplasia. Further, immunologic reconstitution in these patients was not seen following SBA-E-BMT unless and until recovery of thymus function had been observed.

Anti-leukemia potential of interleukin-2 activated natural killer cells after bone marrow transplantation for chronic myelogenous leukemia

The anti-leukemia potential of natural killer (NK) cells has been evaluated in 40 patients transplanted for chronic myelogenous leukemia (CML) to determine whether differences in NK cell function were correlated with subsequent leukemic relapse. Cells from patients and their donors were tested in 51Cr release assays against fully allogeneic CML targets and against cultured K562 targets; cells from 26 patients were tested against host-derived CML targets that were cryopreserved before transplantation. Cultured CML targets (K562) were highly susceptible to lysis by freshly isolated peripheral blood lymphocytes (PBL) and to a greater degree by PBL cultured in medium containing interleukin-2 (IL-2) in all assays performed. In contrast, noncultured CML targets were lysed only by IL-2-activated cells from a subset of patients. When present, lytic activity to CML targets was detectable as early as 3 weeks after bone marrow transplantation, and remained positive throughout the posttransplant period. Optimal lytic activity developed within the first week of culture and required greater than or equal to 250 U/mL of IL-2 in the culture medium. Lytic activity to fully allogeneic and host-derived CML targets appeared to be mediated by CD16+ and CD56+ cells but not by CD3+ cells. Lysis of allogeneic CML targets was variable, but patients could be divided into two groups: those with and those without lytic activity to the majority of targets tested. The basis for the differences in lytic activity could not be ascribed to target susceptibility to lysis, the proportion of NK cells in the cultures, or to the phenotype of the NK cell subsets in the cultures. When tested in parallel, the lytic activity of donor and recipient cultures against host-derived CML targets was highly correlated, suggesting that there may be inherent differences in the ability of NK cells to recognize CML targets. The risk of relapse for patients who failed to generate lytic activity against host-derived CML targets was significantly increased over that for patients with lytic activity against host leukemia. These data indicate that posttransplant immunotherapy with IL-2 designed to activate NK cells will likely augment the graft-versus-leukemia potential of the graft.

Absence of interleukin 2 production in a severe combined immunodeficiency disease syndrome with T cells

We have characterized a child with a severe combined immunodeficiency disease syndrome with increased numbers, but a normal distribution, of CD3+ T cells. This patient's immunological defect appears to be attributable to a selective deficiency in T cell production of IL-2, which may reflect a subtle abnormality in the IL-2 gene locus or a defect in a regulatory factor necessary for IL-2 transcription. The increased numbers of phenotypically normal T cells in this patient suggest that alternative pathways of T cell development exist in man or that IL-2 production intra- and extrathymically is controlled via distinct regulatory mechanisms.

Effects of interleukin-3 on hematopoietic recovery after 5-fluorouracil or cyclophosphamide treatment of cynomolgus primates

Interleukin-3 (IL-3) is a hematopoietic growth factor that supports the growth of early hematopoietic progenitors in vitro. In vivo administration of recombinant human interleukin-3 (rhIL-3) to normal primates results in a modest and delayed leukocytosis secondary to increases in neutrophils, basophils, and eosinophils. We postulated that the effects of rhIL-3 might be more pronounced in hematologically stressed primates, and therefore administered rhIL-3 to primates after intensive myelosuppressive therapy. Primates received either cyclophosphamide (CPM) at 60 mg/kg or 5-fluorouracil (5-FU) at 75 mg/kg i.v. on two consecutive days. Subsequently, rhIL-3 was administered intravenously or subcutaneously at 20 micrograms/kg per d for 14 d. Compared to controls, all rhIL-3 treated primates experienced higher absolute neutrophil count (ANC) nadirs and dramatic decreases in the period of severe neutropenia (ANC less than 500) after myelosuppressive therapy. RhIL-3 administration resulted in a significant basophilia and eosinophilia, which resolved after discontinuation of the drug. RhIL-3 did not enhance erythroid recovery. Platelet recovery was earlier in rhIL-3-treated animals. However, variations in the platelet recovery observed in control animals, precluded accurate estimation of this effect or its significance. Our results indicate that the administration of rhIL-3 following intensive myelosuppressive therapy dramatically enhances myeloid recovery and ablates the predicted period of prolonged severe neutropenia.

High levels of granulocyte and granulocyte-macrophage colony-stimulating factors in cord blood of normal full-term neonates

Because several human hematopoietic growth factors have been identified and shown to be effective for treatment of congenital or iatrogenic neutropenias, and cord blood contains stimulatory activities for blood-forming cells, we postulated that identification of these factors and analysis of their regulatory role in normal neonates would provide a rationale for their use in treating neonatal infections associated with neutropenia. We studied the plasma levels of granulocyte and granulocyte-macrophage colony-stimulating factors (G-CSF and GM-CSF, respectively) and the frequency of granulomonopoietic colony-forming cells (CFU-GM) in the umbilical cord blood of normal term neonates. Plasma growth factor levels were measured by a biologic assay. Circulating hematopoietic progenitors were assayed for colony formation with different recombinant growth factors used as exogenous growth stimulators. The cell cycle status of these progenitors was analyzed by the thymidine suicide technique. At birth the leukocyte count (mean +/- SD) was 11.0 +/- 3.9 x 10(9)L and the neutrophil count was 5.6 +/- 2.6 x 10(9)/L. The incidence of CFU-GM was significantly higher in umbilical cord blood than in normal adult peripheral blood (p less than 0.005) with up to 40% of the cells in S phase (less than 10% in normal adults). Plasma levels of G-CSF and GM-CSF at birth were 40.8 +/- 2.8 U/ml and 19.9 +/- 5.2 U/ml, respectively (normal adult plasma levels 2.5 +/- 1.5 U/ml for G-CSF and undetectable for GM-CSF). These high levels of G-CSF and GM-CSF in umbilical cord blood of normal neonates might play a role in maintaining adequate neutrophil production.

Cytogenetic analysis of chimerism and leukemia relapse in chronic myelogenous leukemia patients after T cell-depleted bone marrow transplantation

Serial cytogenetic studies were performed on 64 patients with chronic myelogenous leukemia (CML) after T cell-depleted allogeneic bone marrow transplantation (BMT). Forty patients with CML in chronic phase (CP) received cytoreduction followed by BMT with HLA-matched T cell-depleted allogeneic marrow. The remaining 24 patients were transplanted in second chronic, accelerated, or blastic phase, or received T cell-depleted grafts with a dose of T cells added back. The Y chromosome and autosomal heteromorphisms were used to distinguish between donor and host cells. Mixed hematopoietic chimerism (presence of donor and host cells) was identified in 90% of patients in first CP. The Philadelphia (Ph) chromosome reappeared in 16 of the 40 first CP CML patients. As expected, patients who had detectable Ph chromosome positive cells at any time during the posttransplant period had a high likelihood of subsequent clinical relapse. Transient disappearance of the Ph positive clone was rarely observed, and was followed by reappearance of the Ph chromosome or clinical relapse. A subset of engrafted patients with greater than 25% host cells within 3 months post-BMT had a significantly shorter survival time free of cytogenetic or clinical relapse compared with other patients. In patients who had received donor T cells added to the T cell-depleted graft, there was a higher proportion of complete chimerism. Clonal progression of Ph positive as well as negative cells was observed and may be the result of radiation induced breakage. Serial cytogenetic studies of patients post-BMT can provide useful information regarding the biologic and clinical behavior of CML.

Effects of hematopoietic growth factors following myeloablation in a primate model

The complex effects of hematopoietic growth factors (granulocyte and granulocyte-macrophage colony-stimulating factors and interleukin 3 and interleukin 1 beta) following myeloablation in juvenile male cynomolgus monkeys was studied. Since the effects of a given cytokine in vivo do not necessarily reflect the in vitro situation, and since cytokines are frequently species specific, extrapolation from rodent models to man may be fraught with inaccuracies. A primate model, therefore, was developed which has provided useful preclinical information on hematopoietic responses, dose response relationships and toxicities associated with administration of recombinant hematopoietic growth factors. This information has direct application to human trials.

Autografting with bone marrow exposed to multiple courses of very high dose cyclophosphamide in vivo and to 4-hydroperoxycyclophosphamide in vitro

Intensive chemotherapy prior to harvesting autologous bone marrow may be advantageous for cancers that infiltrate the bone marrow. This approach, however, may deplete hemopoietic reserves or damage the hemopoietic microenvironment and thereby jeopardize posttransplant engraftment; in vitro treatment of bone marrow to ensure a tumor-free state may enhance the risk of nonengraftment. We addressed these concerns in a pilot study of patients with disseminated neuroblastoma. Bone marrow was harvested after initial intensive therapy that included 1) three to six courses of very high dose cyclophosphamide (CPM) (100-140 mg/kg in five patients, 140-160 mg/kg in nine patients), plus doxorubicin and vincristine, followed by 2) a median of three strongly myelosuppressive courses of cisplatin/VP16. The median interval between courses was 23 days. The marrow was treated in vitro with the CPM congener 4-hydroperoxycyclophosphamide (4-HC) and cryopreserved. It was infused after a massive cytoreduction regimen of melphalan 180 mg/m2 (n = 7) or thiotepa 900 mg/m2 (n = 7), plus cisplatin, BCNU, VP16, and local radiation. All 14 patients reconstituted hemopoiesis (median of 37 days to neutrophils greater than or equal to 500/microliter and of 63 days to platelets greater than 50,000/microliters). The number per kilogram body weight of hemopoietic progenitor cells (CFU-GM, BFU-E) in the autografts correlated significantly with the rate of hematologic recovery. Preharvest CPM dosage, however, did not. The use of thiotepa, as opposed to melphalan, was associated with a significantly slower posttransplant platelet recovery, suggesting a possible adverse effect of high-dose thiotepa on posttransplant hemopoiesis. In sum, while reinforcing evidence of a stem cell sparing effect of CPM, this pilot study more importantly delineates the degree to which high-dose alkylator therapy can be exploited to attain maximal dose intensity beginning at diagnosis. This aggressive treatment approach may have wide applicability, since CPM is among the most active agents against a spectrum of pediatric cancers.

Fusarium infections in patients with hematologic malignancies

Two cases of Fusarium infection in patients with refractory hematologic malignancies are reported. In one patient septicemia progressed to death in septic shock. Miconazole showed some effect in clearing the lesions. There is some evidence that mycotoxins are related with Fusarium infections since severe myositis occurred in our patient. The other patient had a T-cell lymphoma, undergoing allogeneic bone marrow transplantation. The course was also complicated by Fusarium infection of the skin. This patient died of multiorgan failure. Recent literature on Fusarium is reviewed.

Total body irradiation for bone marrow transplantation: the Memorial Sloan-Kettering Cancer Center experience

In May 1979, Memorial Sloan-Kettering embarked on a programme of hyperfractionated TBI (HFTBI), 1320 cGy in 11 fractions over 4 days with partial lung shielding (1 HVL), followed by cyclophosphamide (60 mg/kg/d x 2d) for cytoreduction prior to allogeneic bone marrow transplantation (BMT). Anterior and posterior chest wall electron "boosts" were given to the areas blocked (600 cGy in 2 fractions) on the last two days of treatment. Since then, we have treated over 600 patients with HFTBI, the majority for allogeneic BMT. Several modifications have occurred over the years. We have added a "boost" electron dose of 400 cGy to the testes in all male leukemic patients; this reduced testicular relapses from a rate of 14% (4/28) to 0%. In an attempt to increase engraftment of T-depleted BMTs, we added one additional fraction; since our present dose/fraction was also increased to 125 cGy, we now deliver a total dose of 1500 cGy in 12 fractions over 4 days for allogeneic transplants. Tolerance to HFTBI has been excellent relative to the single dose (SD) regimen utilised prior to May, 1979. The incidence of fatal interstitial pneumonitis (IP) decreased from 50% in the SD regimen to 18% after the introduction of HFTBI. In children, the incidence of IP was only 4% with HFTBI. With the introduction of T-depleted marrows, fatal IP in adults has decreased also, e.g. to less than 10% in CML patients. With conventional BMT after HFTBI, relapse at 5 years has been exceedingly low (e.g. in children, 13% for ALL, 2nd remission and 0% for AML, 1st remission) and engraftment has been 100%. With matched T-depleted BMT, rejections have occurred in 15% overall; the incidence of graft failure has not been reduced by the higher dose of HFTBI. Relapses in this setting are equivalent to relapses with conventional BMT for AML, but appear to be increased for ALL. Radiobiological findings related to HFTBI will also be discussed.

Effects of IL-1 on hematopoietic progenitors after myelosuppressive chemoradiotherapy

Recently it has been recognized that IL-1 plays an important role in hematopoietic regulation. Administration of 5-fluorouracil (5-FU) to mice causes prolonged neutropenia. rHIL-1 injected to mice after 5-FU, accelerated the recovery of hematopoietic progenitors and blood neutrophils. The combination of rhIL-1 and rhG-CSF reduced the neutropenic period significantly. Sublethal irradiation of mice induced profound neutropenia for 3 weeks which was associated with 80% mortality. Administration of rhIL-1 20 hours prior to or 2 hours post irradiation resulted in a significantly improved survival and rapid recovery of the neutrophil count. IL-1 administered alone or in combination with other colony stimulating factors to spontaneous breast tumor bearing mice following 5-FU therapy resulted in a rapid recovery of neutrophils, improved survival, and markedly reduced the tumor mass. Experiments in primates demonstrated that rhIL-1 administered to 5-FU treated animals shortened the neutropenic period from 30 to 17 days and increased the number of marrow progenitors responsive to other CSFs. Prolonged administration of IL-1 (14 days) to these animals resulted in a delayed neutrophil recovery as compared to animals receiving short courses of IL-1. rhIL-1 administered to primates receiving marrow grafts after lethal irradiation, did not result in rapid hematopoietic recovery. In humans, studies with CD-34 positive marrow cells showed that IL-1 had a radioprotective effect on a committed and early marrow progenitors. These data show the therapeutic potential of IL-1 in the treatment of chemoradiotherapy induced myelosuppression.

Graft failure after T-cell-depleted human leukocyte antigen identical marrow transplants for leukemia: II. In vitro analyses of host effector mechanisms

To identify mechanisms potentially contributing to graft failure, 19 leukemic recipients of T-cell-depleted marrow transplants who failed to engraft following a transplant of HLA identical sibling marrow depleted of T cells by soybean agglutinin (SBA) and sheep erythrocytes (E) were evaluated. Peripheral blood mononuclear cells isolated at the time of failure were consistently of host origin, bearing the phenotype of suppressor T cells (CD3+, CD8+, Leu 7+). A direct cytolytic effect on 51Cr-labeled donor-derived target cells was not detected, a finding that contrasts with the donor-specific cytotoxic host T lymphocytes that have been regularly observed in patients rejecting HLA nonidentical SBA -E- BMTs. However, these host T cells did exhibit a strong and specific suppressive activity against the donor marrow CFU-GM in vitro. Furthermore, in contrast to prior findings in durably engrafted recipients of SBA -E- BMTs, the lymphocytes isolated prior to or at the time of graft failure lacked natural killer surface antigen expression and effector function.

Detection of posttransplant minimal disease chronic myelogenous leukemia by bcr rearrangement analysis

Until recently, cytogenetic detection of the Philadelphia chromosome (Ph) was the only reliable test to diagnose chronic myelogenous leukemia (CML) and detect minimal disease or early relapse following treatment. However, the recently developed ability to detect the Ph chromosome as a rearrangement in the bcr gene of chromosome 22 permits identification of the leukemic clone comprising as little as 5% of the cell population. We present results of simultaneous cytogenetic and DNA rearrangement studies in 28 CML patients considered for or treated with bone marrow transplantation. Our results show that the molecular method is significantly more sensitive than the cytogenetic method in the detection of minimal disease Ph-positive clones.

Clinical promise of new hematopoietic growth factors: M-CSF, IL-3, IL-6

Hematopoietic growth factors are reaching maturity in clinical trials. There is a wide spectrum of disorders of bone marrow dysfunction that can be effectively treated by currently available hematopoietic growth factors. Newer growth factors are entering clinical trials. rhM-CSF has a variety of biological activities. It may be useful in hematology/oncology and infectious disease settings. Recombinant human interleukin-3 (rhIL-3) has undergone extensive trials in nonhuman primates that suggest that this hematopoietin is a potent stimulus of bone marrow function following chemotherapy and may be synergistic with other growth factors, such as rhGM-CSF. Other pleotrophic hematopoietic growth factors, such as interleukin-6, are currently being developed and may exert a wide spectrum of activities in disease states.

Loss of tolerance associated with disappearance of B cells in a patient sequentially transplanted with paternal and maternal bone marrow for the treatment of severe combined immunodeficiency disease

We have studied the tolerance of engrafted T cells from a severe combined immunodeficiency disease patient sequentially transplanted with T-cell-depleted bone marrow from both HLA haploidentical parents. The T cells from this patient were shown by HLA typing and cytogenetic analysis to be of material origin (donor of the second graft) while HLA typing of peripheral E--populations and of an Epstein-Barr virus-transformed B-cell line established 2 1/2 years after transplantation revealed the presence of host, maternal, and paternal (donor of the first graft) HLA antigens. When tested at 30 and 60 months after the last transplant, engrafted T cells from this patient had only weak mixed lymphocyte culture reactivity to paternal cells which could be inhibited by monoclonal antibodies to HLA-DQ and DR but not by anti-DP. T cells obtained 60 months after transplant were stimulated with paternal cells in both bulk and limiting dilution cultures and failed to generate typical allocytotoxic cells to paternal T- or B-cell targets. Mixed lymphocyte cultures performed at 71 months revealed an increased proliferative response by patient cells to paternal antigens; however, the engrafted T cells remained tolerant to maternal and host antigens. Limiting dilution analysis performed at this time revealed the presence of cytolytic cells directed to paternal antigens. There were no detectable B cells (only identified source of paternal antigen) as measured by immunofluorescent analysis of peripheral blood, nor any evidence of B-cell function as assessed by in vitro assays (proliferation to staphylococcus aureus Cowen strain A and mitogen-stimulated immunoglobulin production) or in vivo production of serum immunoglobulin at 60 and 71 months. The appearance of alloreactivity associated with the loss of B cells in this patient further supports the conclusion that the maintenance of tolerance to major histocompatibility complex disparate cells requires the continued in vivo presence of cells bearing the tolerizing antigens.

Retroviral vector-mediated high-efficiency expression of adenosine deaminase (ADA) in hematopoietic long-term cultures of ADA-deficient marrow cells

Two recombinant retroviral vectors encoding the cDNA of the human adenosine deaminase (ADA; EC 3.5.4.4) gene and the bacterial neomycin resistance (Neo) gene have been used to transduce bone marrow cells obtained from four patients affected by the ADA-deficient variant of severe combined immunodeficiency. By utilizing the long-term marrow culture system, freshly isolated bone marrow cells were subjected to multiple infection cycles with cell-free supernatants containing high titers of viral vector and then maintained in long-term marrow culture in the absence of any overt selection pressure. By using this experimental protocol, about 30-40% of the hematopoietic progenitors were productively transduced with the viral vector, as judged by the appearance of G418-resistant colonies derived from granulocyte/macrophage and multipotent hematopoietic progenitor cells. The vector-encoded human ADA gene was expressed efficiently in both the myeloid and lymphoid progeny of the cultured bone marrow cells, reaching levels between 15% and 100% as compared to the levels of ADA in normal bone marrow cells. The efficiency of gene transfer and ADA production was proportional to the number of infection cycles. Furthermore, transduction of the ADA vectors into the bone marrow cells derived from an ADA-deficient patient restored the capacity of the cells to respond to phytohemagglutinin and interleukin 2.

Effects of interleukin-1 on hematopoietic progenitors: evidence of stimulatory and inhibitory activities in a primate model

The effects of recombinant human interleukin-1 rhIL-1 beta (rhIL-1b) on hematopoietic recovery following chemotherapy in a primate model were investigated. Cynomolgus monkeys received 1 microgram/kg/day rhIL-1b intravenously for 2, 7, and 14 days following 5-Fluorouracil (5-FU) treatment (75 mg/kg x 2 days). Compared with controls, a significantly shortened time to achieve an absolute neutrophil (ANC) count over 500/microL was observed in animals receiving 2- and 7-day courses of rhIL-1b (17 v 30 days), while animals receiving a 14-day course of rhIL-1b achieved an ANC over 500/microL by 23 days. Concomitantly, a marked increase in granulocyte-macrophage colonies (CFU-GM) was observed at 14 days following 5-FU in animals receiving 2- and 7-day rhIL-1b courses. In animals receiving a 14-day rhIL-1b course, a significant increase in CFU-GM relative to control was not seen until 21 days post 5-FU. Utilizing a serum-free colony assay system, a 50% inhibition of normal marrow CFU-GM growth was observed with the addition of sera obtained on day 9 post 5-FU from animals receiving rhIL-1b for 14 days. Sera obtained at any time from animals receiving 2- and 7-day rhIL-1b treatment did not show any growth inhibition. Addition of antibodies to TNFa to the coculture assay abrogated the CFU-GM growth inhibition. TNFa levels in sera with the inhibitory activity was relatively high (918 pg/mL). Our data indicate that rhIL-1b enhances hematopoietic recovery following 5-FU if administered for short periods of time (less than 7 days), whereas prolonged administration has a counterproductive effect that is due in part to the induction of TNFa production.

Characterization of B cells in severe combined immunodeficiency disease

The circulating lymphoid cells of eight consecutive untreated infants with severe combined immunodeficiency disease (SCID) with B cells were analyzed for surface marker expression and function. The B cells of these children expressed sIg, HLA-DR, CD19 (B4), CD20 (B1), CD21 (B2), Leu-8, and lacked expression of CD10 (CALLA), as do normal peripheral blood B lymphocytes. SCID B cells also expressed antigens that are normally absent or present on only a minor subset of circulating adult B lymphocytes, including CD1c (M241), CD38 (OKT10), CD23 (PL13), with or without concomitant CD5 (Leu-1) expression. The B cells of these children were capable of proliferating in vitro when stimulated with Staphylococcus aureus Cowan I. However, in the presence of pokeweed mitogen, S. aureus Cowan I, and normal T cells, the sIg+ cells of these children produced only IgM. Studies performed on normal B cells obtained from cord blood, young children, and adults reveal that whereas cord blood B cells are predominantly CD1c, CD38, and CD23 positive, B-cell expression of these antigens decreases with age. Cord blood B cells, similar to SCID B cells, produce only IgM when stimulated in vitro with pokeweed mitogen and S. aureus Cowan I. Based on these observations, we hypothesize that SCID B cells represent a population of B cells present during normal B-cell ontogeny which becomes a minor subset when an individual develops full immunologic competence.

T cell depletion of human bone marrow. Comparison of Campath-1 plus complement, anti-T cell ricin A chain immunotoxin, and soybean agglutinin alone or in combination with sheep erythrocytes or immunomagnetic beads

The aim of this study was to compare the extent of in vitro T cell depletion and recovery of hematopoietic progenitor cells achieved with five methods of T cell depletion. Bone marrow samples from the same source were treated with monoclonal antibody Campath-1 (CP1) and human complement, XomaZyme-H65 (anti-T cell ricin A chain immunotoxin), or soybean agglutinin (SBA) alone or in combination with sheep erythrocytes (EAET) or a cocktail of immunomagnetic beads (B) directly coated with anti-CD2, anti-CD3, or anti-CD8 monoclonal antibodies. Residual T cells were enumerated by limiting dilution analysis, EAET rosetting, and proliferative responses to phytohemagglutinin. The results of this study demonstrated the following reductions in BM T cells as detected by limiting dilution analysis (mean % control): SBA+B (99.9%), SBA+EAET (99.8%), CP1+C' (99.4%), anti-T cell ricin A chain immunotoxin (99.0%), and SBA alone (94.2%). Neither PHA response nor enumeration of residual EAET rosettes provided discriminating differences in the degree of T cell depletion by treatment method when T cell reductions exceeded 99.0% by LDA. These results demonstrate the ability of CP1+C', XomaZyme-H65, and SBA plus sheep erythrocyte or magnetic bead depletion to achieve a greater than 99% reduction of BM T cells and the importance of limiting dilution analysis in defining differences in T cell numbers when depletion exceeded 99%.