Genetic diversity within leukemia-associated immunophenotype-defined subclones in AML.

Acute myeloid leukemia (AML) is a highly heterogeneous disease showing dynamic clonal evolution patterns over time. Various subclones may be present simultaneously and subclones may show a different expansion pattern and respond differently to applied therapies. It is already clear that immunophenotyping and genetic analyses may yield overlapping, but also complementary information. Detailed information on the genetic make-up of immunophenotypically defined subclones is however scarce. We performed error-corrected sequencing for 27 myeloid leukemia driver genes in 86, FACS-sorted immunophenotypically characterized normal and aberrant subfractions in 10 AML patients. We identified three main scenarios. In the first group of patients, the two techniques were equally well characterizing the malignancy. In the second group, most of the isolated populations did not express aberrant immunophenotypes but still harbored several genetic aberrancies, indicating that the information obtained only by immunophenotyping would be incomplete. Vice versa, one patient was identified in which genetic mutations were found only in a small fraction of the immunophenotypically defined malignant populations, indicating that the genetic analysis gave an incomplete picture of the disease. We conclude that currently, characterization of leukemic cells in AML by molecular and immunophenotypic techniques is complementary, and infer that both techniques should be used in parallel in order to obtain the most complete view on the disease.

Functionally active NKG2A-expressing natural killer cells are elevated in rheumatoid arthritis patients compared to psoriatic arthritis patients and healthy donors.

OBJECTIVES: Natural killer cell receptors (NKR) have been implicated in rheumatoid (RA) and psoriatic arthritis (PsA) pathogenesis. To gain more insight into their role, we characterised NKR (co-)expression patterns on NK and T cells and NK cell function in RA and PsA. METHODS: The frequency of NK and T cells expressing killer like immunoglobulin (KIR) and NKG2 receptors and natural cytotoxicity receptors was assessed by 10-colour flow cytometry in peripheral blood of 23 RA, 12 PsA patients and 18 healthy donors (HD). NK cell cytotoxicity and IFN-gamma production was assessed in 8 RA patients and 8 HD. RESULTS: In RA but not PsA, the frequency of NK cells (median; range) expressing NKG2A (42%; 14-81%) was elevated compared to HD (23%; 9-58%). NKG2A⁺ NK cells predominantly lack KIR, but display normal cytotoxicity and IFN-γ production. In contrast, RA patients with normal NKG2A⁺ NK cell frequency have less functional NK cells compared to HD. T cells expressing Fc-gamma receptor CD16 were elevated in RA (median 0.75%) versus HD (0.3%). Furthermore, T cells expressing the KIRs CD158ah in both RA (0.7%) and PsA (0.3%), and CD158e1e2 in RA (1.5%) were elevated compared to HD (0.2% and 0.4%, respectively). In RA, CD4⁺ T cells expressing the KIRs CD158ah, CD158b1b2j and CD158e1e2 were low (<2%) but significantly elevated compared to HD. CONCLUSIONS: This study demonstrates the presence of an elevated, functionally active NKG2A⁺ KIR- NK cell population in RA. Together with an elevated frequency of NKR-expressing T cells, these changes may reflect differential pathogenetic involvement.

A pilot study on the immunogenicity of dendritic cell vaccination during adjuvant oxaliplatin/capecitabine chemotherapy in colon cancer patients.

BACKGROUND: Dendritic cell (DC) vaccination has been shown to induce anti-tumour immune responses in cancer patients, but so far its clinical efficacy is limited. Recent evidence supports an immunogenic effect of cytotoxic chemotherapy. Pre-clinical data indicate that the combination of chemotherapy and immunotherapy may result in an enhanced anti-cancer activity. Most studies have focused on the immunogenic aspect of chemotherapy-induced cell death, but only few studies have investigated the effect of chemotherapeutic agents on the effector lymphocytes of the immune system. METHODS: Here we investigated the effect of treatment with oxaliplatin and capecitabine on non-specific and specific DC vaccine-induced adaptive immune responses. Stage III colon cancer patients receiving standard adjuvant oxaliplatin/capecitabine chemotherapy were vaccinated at the same time with keyhole limpet haemocyanin (KLH) and carcinoembryonic antigen (CEA)-peptide pulsed DCs. RESULTS: In 4 out of 7 patients, functional CEA-specific T-cell responses were found at delayed type hypersensitivity (DTH) skin testing. In addition, we observed an enhanced non-specific T-cell reactivity upon oxaliplatin administration. KLH-specific T-cell responses remained unaffected by the chemotherapy, whereas B-cell responses were diminished. CONCLUSION: The results strongly support further testing of the combined use of specific anti-tumour vaccination with oxaliplatin-based chemotherapy.

Rapamycin and MPA, but not CsA, impair human NK cell cytotoxicity due to differential effects on NK cell phenotype.

Cyclosporin A (CsA), rapamycin (Rapa) and mycophenolic acid (MPA) are frequently used for GVHD prophylaxis and treatment after allogeneic stem cell transplantation (SCT). As NK cells have received great interest for immunotherapeutic applications in SCT, we analyzed the effects of these drugs on human cytokine-stimulated NK cells in vitro. Growth-kinetics of CsA-treated cultures were marginally affected, whereas MPA and Rapa severely prevented the outgrowth of CD56(bright) NK cells. Single-cell analysis of NK cell receptors using 10-color flow cytometry, revealed that CsA-treated NK cells gained a similar expression profile as cytokine-stimulated control NK cells, mostly representing NKG2A(+) KIR(-) NCR(+) cells. In contrast, MPA and Rapa inhibited the acquisition of NKG2A and NCR expression and NK cells maintained an overall NKG2A(-) KIR(+) NCR(+/-) phenotype. This was reflected in the cytolytic activity, as MPA- and Rapa-treated NK cells, in contrast to CsA-treated NK cells, lost their cytotoxicity against K562 target cells. Upon target encounter, IFN-γ production was not only impaired by MPA and Rapa, but also by CsA. Overall, these results demonstrate that CsA, MPA and Rapa each have distinct effects on NK cell phenotype and function, which may have important implications for NK cell function in vivo after transplantation.

Long-term follow-up results after autologous haematopoietic stem cell transplantation for severe systemic sclerosis.

OBJECTIVE: Systemic sclerosis (SSc) is a generalised autoimmune disease, causing morbidity and a reduced life expectancy, especially in patients with rapidly progressive diffuse cutaneous SSc. As no proven treatment exists, autologous haematopoietic stem cell transplantation (HSCT) is employed as a new therapeutic strategy in patients with a poor prognosis. This study reports the effects on survival, skin and major organ function of HSCT in patients with severe diffuse cutaneous SSc. PATIENTS AND METHODS: A total of 26 patients were evaluated. Peripheral blood stem cells were collected using cyclophosphamide (4 g/m2) and rHu G-CSF (5 to 10 microg/kg/day) and were reinfused after positive CD34+ selection. For conditioning, cyclophosphamide 200 mg/kg was used. RESULTS: After a median follow-up of 5.3 (1-7.5) years, 81% (n = 21/26) of the patients demonstrated a clinically beneficial response. The Kaplan-Meier estimated survival at 5 years was 96.2% (95% CI 89-100%) and at 7 years 84.8% (95% CI 70.2-100%) and event-free survival, defined as survival without mortality, relapse or progression of SSc, resulting in major organ dysfunction was 64.3% (95% CI 47.9-86%) at 5 years and 57.1% (95% CI 39.3-83%) at 7 years. CONCLUSION: This study confirms that autologous HSCT in selected patients with severe diffuse cutaneous SSc results in sustained improvement of skin thickening and stabilisation of organ function up to 7 years after transplantation.

Evaluation of 'out-of-specification' CliniMACS CD34-selection procedures of hematopoietic progenitor cell-apheresis products.

BACKGROUND: Immunomagnetic selection of CD34(+) hematopoietic progenitor cells (HPC) using CliniMACS CD34 selection technology is widely used to provide high-purity HPC grafts. However, the number of nucleated cells and CD34+ cells recommended by the manufacturer for processing in a single procedure or with 1 vial of CD34 reagent is limited. METHODS: In this retrospective evaluation of 643 CliniMACS CD34-selection procedures, we validated the capacity of CliniMACS tubing sets and CD34 reagent. Endpoints of this study were the recovery and purity of CD34+ cells, T-cell depletion efficiency and recovery of colony-forming units-granulocyte-macrophage (CFU-GM). RESULTS: Overloading normal or large-scale tubing sets with excess numbers of total nucleated cells, without exceeding the maximum number of CD34+ cells, had no significant effect on the recovery and purity of CD34+ cells. In contrast, overloading normal or large-scale tubing sets with excess numbers of CD34+ cells resulted in a significantly lower recovery of CD34+ cells. Furthermore, the separation capacity of 1 vial of CD34 reagent could be increased safely from 600 x 10(6) CD34+ cells to 1000 x 10(6) CD34+ cells with similar recovery of CD34(+) cells. Finally, T-cell depletion efficiency and the fraction of CD34+ cells that formed CFU-GM colonies were not affected by out-of-specification procedures. DISCUSSION: Our validated increase of the capacity of CliniMACS tubing sets and CD34 reagent will reduce the number of selection procedures and thereby processing time for large HPC products. In addition, it results in a significant cost reduction for these procedures.

Cytotoxicity of CD3-ricin A chain immunotoxins in relation to cellular uptake and degradation kinetics.

The cytotoxicity of WT32 (CD3)-ricin A immunotoxin (IT) to the acute lymphoblastic leukemia T-cell line Jurkat was compared with the rate of internalization and intracellular degradation of WT32 and WT32-ricin A during continuous exposure. Moreover, the influence of NH4Cl and monensin on these processes was studied. Based on protein synthesis inhibition ([3H]leucine incorporation), it appeared that cytotoxicity was not fully expressed directly after exposure to IT due to a delay in either the internalization of membrane-bound IT or the action of intracellular ricin A. Varying the duration of incubation and postponing [3H]leucine addition for up to 24 h after initiation showed that cytotoxicity occurred in two phases, rapid internalization of initially bound IT followed by a continuous but slower uptake, possibly due to reexpression of the CD3 antigen. No differences were found in the rate of internalization and degradation of 125I-labeled WT32 and WT32-ricin A. Internalization started rapidly after binding at 37 degrees C, was fastest during the first 12 h (+/- 360,000 molecules/cell), and continued for at least 24 h (+/- 420,000 molecules/cell). Exocytosis of intracellularly degraded molecules became measurable after 1 to 2 h of incubation at 37 degrees C and increased to approximately 400,000 molecules/cell in 24 h. After 4 h of incubation at 37 degrees C the number of internalized molecules exceeded the amount of WT32 that could maximally bind to the cell membrane (+/- 150,000 molecules/cell), confirming reexpression of antigen. The addition of NH4Cl and monensin enhanced the cytotoxicity of WT32-ricin A, probably due to an increased intracellular amount of IT. These agents appeared to reduce strongly the degradation of internalized WT32, resulting in an accumulation of intracellular molecules. NH4Cl was most effective during the first 12 h of incubation, whereas monensin increased the amount of intracellular WT32 molecules after 2 to 24 h. Our observations suggest that incubation conditions for the optimal cytotoxicity of IT treatment can be predicted by studying the internalization and degradation of the IT or respective monoclonal antibody.

Effect of isotype on internalization and cytotoxicity of CD19-ricin A immunotoxins.

We analyzed the effect of isotype variation on effectiveness of B-cell CD19 immunotoxins (IT) by using class switch variants (CLB-B4-IgG1 and CLB-B4-IgG2a) conjugated to ricin A. Notably, IgG1-IT appeared to be approximately 100-fold more potent than IgG2a-IT toward B-cell lines Daudi and KM3. Binding and internalization studies with 125I-labeled monoclonal antibodies (mAbs) revealed a higher cellular uptake of IgG1 compared to IgG2a, despite similar binding affinities. Following removal of the Fc part, both mAbs internalized at the same rate as IgG2a, indicating that the Fc part of IgG1 is involved in enhanced cellular uptake. The involvement of Fc gamma RII (CD32) in this process was demonstrated by a decreased cytotoxicity of IgG1-IT (and not IgG2a-IT) in the presence of Fc gamma RII-blocking mAbs AT10 or IV.3. To identify the isoform responsible for this phenomenon, internalization of IgG1 and IgG2a in 11 B-cell lines and malignant B-cells of 8 patients was compared with expression of Fc gamma RII subclasses. In addition to four cell lines (Daudi, KM3, Nalm6, and Raji), the malignant B-cells of two patients showed enhanced uptake of IgG1 relative to IgG2a. Only the Fc gamma RIIa transcript was found in all B-cells. Furthermore, enhanced uptake of IgG1 correlated with rosetting of erythrocytes sensitized with anti-glycophorin A mAb of IgG1 isotype rather than with Fc gamma RIIa membrane expression levels. These data support the idea that functional Fc gamma RIIa is involved in the enhanced IgG1 uptake observed in a subset of B-cells. Our study, therefore, points to an important role for the Fc region of IT in the delivery of cytotoxic effects.

Influence of cytotoxicity enhancers in combination with human serum on the activity of CD22-recombinant ricin A against B cell lines, chronic and acute lymphocytic leukemia cells.

Despite the strong in vitro activity of some immunotoxins (ITs), clinical application did not result in complete cure. The outcome of therapy may be improved by combining ITs with IT-cytotoxicity enhancing agents. We studied the effect of various agents that influence the intracellular routing of ITs on the activity of the anti-B cell IT CD22-recombinant (rec) ricin A. In protein synthesis inhibition assays the carboxylic ionophores monensin and nigericin enhanced the activity of the IT 117- and 382-fold, respectively, against the cell line Daudi, and 81- and 318-fold, respectively, against the cell line Ramos. IT activity to Daudi and Ramos was enhanced to a lesser extent by the lysosomotropic amines chloroquine (14- and 11-fold, respectively) and NH4Cl (nine- and 10-fold, respectively). However, the combination of NH4Cl and chloroquine induced more than an additive effect (145- and 107-fold, respectively). Cytotoxicity was not influenced by brefeldin A, all-trans retinoic acid (ATRA), verapamil and perhexiline maleate. Bacitracin enhanced the IT cytotoxicity in contrast to the other protease inhibitors aprotinin, leupeptin and soybean trypsin inhibitor, albeit enhancement was weak (two-fold). The enhancers exerted only a negligible effect on bone marrow progenitor cells. We recently developed a flow cytometric cytotoxicity assay in which cell elimination can be assessed. In order to detect enhancement in this assay, we used 5 x 10(-11) M IT (approximately the 50% protein synthesis inhibiting dose (ID50)). This concentration killed 41% of the Daudi cells and 42% of the Ramos cells. In the presence of 10 nM monensin the IT killed 74% and 99% and in the presence of 10 nM nigericin 96% and 99% of the Daudi and Ramos cells, respectively. At 10(-8) M, CD22-rec ricin A eliminated malignant cells originating from three patients with B-CLL (0.42 log) and two with B-ALL (0.19 log) patients. Cytotoxicity to malignant cells was enhanced by NH4Cl, chloroquine, monensin and nigericin. The combination of NH4Cl and chloroquine enhanced the activity most effectively (up to 2.06 log). To determine the applicability of the IT in combination with enhancers in vivo we investigated the effect of human serum. Human serum inhibited IT activity which could not be restored by monensin and nigericin because of complete inhibition of these enhancers by serum. In contrast, chloroquine partially restored the activity of CD22-rec ricin A in the presence of human serum. We conclude that monensin, nigericin and the combination of NH4Cl and chloroquine can be used instead of NH4Cl to potentiate CD22-rec ricin A activity in purging autologous bone marrow transplants contaminated with malignant B cells. Chloroquine might be a promising enhancer of CD22-rec ricin A for treating patients in vivo.

Induction of graft-versus-leukemia to prevent relapse after partially lymphocyte-depleted allogeneic bone marrow transplantation by pre-emptive donor leukocyte infusions.

In this prospective study we analyzed pre-emptive donor leukocyte infusions (DLI) in 82 consecutive patients transplanted with partially T cell-depleted grafts for acute myeloid leukemia, acute lymphoid leukemia, chronic myeloid leukemia, refractory anemia with excess of blasts, refractory anemia with excess of blasts in transformation and multiple myeloma. Donors were HLA-identical siblings. Patients without significant acute (>grade 1) and/or chronic GVHD were scheduled to be treated with DLI (35 patients) and 31 actually received DLI. Patients who developed acute GVHD >grade 1 and/or chronic GVHD were not scheduled to receive DLI and served as a comparison group (47 patients). The median interval between BMT and DLI was 22 weeks. The first six patients received 0.7 x 10(8) CD3+ cells/kg body weight (b.w.). Five out of these six patients developed acute GVHD (grade 1: n = 2, grade 3: n = 2 and grade 4: n= 1) which was more frequent and more severe than we had anticipated. In the next 25 patients the number of T lymphocytes was diminished to 0.1 x 10(8) CD3+ cells/kg b.w. which resulted in less frequent and less severe GVHD. Eight patients in this group developed acute GVHD (grade 1: n = 4, grade 2: n = 4) and three patients had limited chronic GVHD. Patients in the DLI group needed more time to establish complete donor chimerism confirmed by a higher number of mixed chimeras at 6 months after BMT. The projected 3-year probability of disease-free survival was 77% for the 35 patients intended to treat with DLI and 45% for the patients of the comparison group (P = 0.024). Relapse rate at 36 months after transplantation was 18% in the patients who were intended to treat with DLI and 44% in the comparison group (P = 0.026). We conclude that pre-emptive DLI is feasible and generates favorable relapse rates in patients who are at high risk for relapse. Furthermore, the incidence and severity of GVHD disease after DLI is dependent on the number of CD3+ cells infused.

Long-term follow-up of persisting mixed chimerism after partially T cell-depleted allogeneic stem cell transplantation.

Using red cell phenotyping (RCP) and/or cytogenetics (CYT) we identified 19 patients with persisting mixed chimerism (MC) among 231 patients transplanted with partially T cell-depleted stem cell grafts from HLA-identical siblings. Persisting MC is defined as MC for more than 2 years in patients without any evidence of relapse. Median leukemia-free survival in these patients was 150 (range, 50-218) months. Diagnoses were ALL (n= 10); AML (n = 2); CML (n = 2); NHL (n = 2); MDS (n= 1); MM (n = 1) and SAA (n = 1). Purpose of this study was the long-term follow-up of MC and definition of patterns of chimerism in the various subsets of PBMCs and granulocytes. Using a PCR-STR technique CD3(+)/CD4(+) (T4 lymphocytes), CD3(+)/CD8(+) (T8 lymphocytes), CD45(+)/CD19(+) (B lymphocytes), CD45(+)/CD14(+) (monocytes), CD45(+)/CD15(+) (granulocytes) and CD3(-)/CD56(+) (NK-cells) were analyzed. The majority of patients with persisting MC were conditioned with a less intensive conditioning regimen and had little GVHD. Sequential monitoring of the chimerism resulted in a group of patients (n = 7) with very slow transient mixed chimerism that resulted in complete DC after median 7 years. Another nine patients had a relatively high percentage of persisting autologous cells for a median of 12 years and in three patients we observed a stable low percentage of autologous cells. Only two out of 19 patients (AML-CR1, CML-CP1) relapsed during follow-up. Both patients had a relatively high percentage of autologous cells. Chimerism in granulocytes and PBMC subsets was analyzed at a median of 8 years after SCT in nine patients. In five patients mixed chimerism simultaneously detected by RCP and CYT was associated with MC in all subsets. Within each individual patient the percentages of donor and recipient cells were very different between the different subsets. Two CML-CP1 patients were mixed chimera in only two subsets and in one patient these subsets represented pending relapse. In another two patients mixed chimerism with a very low number of autologous red cells was not found in the PBMCs because of the different sensitivity level of the RCP and the PCR-STR technique. We conclude that in patients with persisting mixed chimerism after partially T cell-depleted SCT a remarkable number of patients had lymphoid malignancies, the majority of the patients were conditioned with less intensive conditioning regimens and the mixed chimerism was not correlated with relapse. Chimerism in granulocytes and PBMC subsets did show great intra-individual differences in the subsets and these data correlated well with RCP and CYT data with the exception of the NK cells.

Prolonged exposure to cytosine arabinoside in the presence of hematopoietic growth factors preferentially kills leukemic versus normal clonogenic cells.

We investigated the cytotoxic effect of the cell cycle-specific agent cytosine arabinoside (Ara-C) on clonogenic leukemic and normal bone marrow cells. To overcome kinetic resistance and to increase cytotoxicity, the cells were exposed to Ara-C in liquid culture medium for extended time periods, that is, 5 and 10 days. Subsequently the number of surviving clonogenic cells was determined in a semi-solid assay. All cultures were stimulated with the combination of recombinant human interleukin 3 (rhIL-3), granulocyte-macrophage colony-stimulating factor (rhGM-CSF), and granulocyte colony-stimulating factor (rhG-CSF) to induce optimal cell proliferation. In comparison to normal clonogenic bone marrow cells (granulocyte-macrophage colony-forming units, CFU-GM) 5-day Ara-C exposure resulted in an equal to a slightly more effective kill of leukemic colony-forming cells (CFU-L). The Ara-C dose resulting in 50% inhibition (ID50) was 1.6 +/- 1.6 x 10(-8) M for CFU-L (n = 9) and 6.7 +/- 4.3 x 10(-8) M for CFU-GM (n = 4, p = 0.096). Prolongation of the Ara-C exposure time from 5 to 10 days increased the cytotoxicity towards the majority of the leukemic clonogenic cells (ID50: 0.8 +/- 0.6 x 10(-8) M) but not towards CFU-GM (ID50: 5.7 +/- 2.8 x 10(-8) M). Overall, significantly more leukemic clonogenic cells than normal CFU-GM were killed after 10 days of exposure to Ara-C (p = 0.039). These results indicate that leukemic clonogenic cells can be eradicated preferentially by prolonged exposure to low dosages of Ara-C in the presence of hematopoietic growth factors with relative preservation of the normal hematopoietic progenitor cells.

Origin of T-lymphocytes in human mixed hematopoietic colonies.

The presence of T-lymphocytes in mixed hematopoietic colonies (CFU-MIX) has been reported by some investigators. Though depletion before culturing was performed, residual T cells might be responsible for the observed phenomenon. Using nondepleted marrow or bone marrow depleted to about 2%, T-lymphocytes could be detected in mixed colonies. However, reduction of the T-lymphocytes to less than 0.7% by using a modified E-rosette technique or a cocktail of anti-T-cell monoclonal antibodies (WT1, WT32, WT82) in the presence of baby rabbit complement, resulted in mixed colonies free of T-lymphocytes. After addition of 1.75% T-lymphocytes to this T-cell-depleted bone marrow, T-lymphocytes could be detected in most mixed colonies, but not after the addition of the same percentage of irradiated T-lymphocytes. The presence of T cells in mixed colonies was determined by an adapted immunofluorescence technique (WT32 plus GAM-FITC). The results indicate that mononuclear cells with T-lymphocyte antigens are not the offspring of mixed hematopoietic colony-forming progenitors, but of a low number of T-lymphocytes contaminating the bone marrow after insufficient T-cell depletion.

Outcome of allogeneic bone marrow transplantation with lymphocyte-depleted marrow grafts in adult patients with myelodysplastic syndromes.

Thirty-five patients with myelodysplastic syndromes (MDS) were treated with BMT between 1986 and 1994. Their median age was 41 years (range 23-60). Thirteen patients had transfusion-dependent refractory anaemia (RA). Twenty-two patients suffered from more advanced stages of MDS, 15 being in complete remission (CR) after chemotherapy. In 31 recipients, pretransplant conditioning consisted of cyclophosphamide and TBI with or without the addition of idarubucin; four patients were conditioned with other schedules. Donors were genotypically HLA-identical and MLC-negative siblings in 32, and others in three cases. All patients received a graft depleted of 98% of T lymphocytes using counterflow centrifugation. Fourteen patients are alive and in continuous remission with a median follow-up of 20 months (range 15-113) after BMT. Seven patients relapsed between 3 and 18 months after BMT and subsequently died. Fourteen transplantation-related deaths occurred. Outcome in patients under and over 40 years old was comparable. The probability of disease-free survival (DFS) at 2 years after BMT was 39% (95% confidence interval (CI), 22-56%). Considering patients with HLA-identical and MLC-negative sibling donors transplanted for RA (n = 11) or more advanced stages of MDS in CR (n = 14), the probabilities of DFS were 73% (95% CI, 47-99%) and 42% (95% CI, 15-69%), respectively. This indicates that BMT with lymphocyte-depleted grafts can cure a substantial number of relatively old patients with MDS, especially when grafts from HLA-identical and MLC-negative siblings are used and patients are suffering from RA.

Outcome of T cell-depleted transplantation after conditioning with an intensified regimen in patients aged 50 years or more is comparable with that in younger patients.

One hundred and thirty-one patients were transplanted for AML-CR1, ALL-CR1 or CML-CP1 after conditioning with 120 mg/kg body weight cyclophosphamide and 2 x 4.5 Gy TBI. Conditioning was intensified with the addition of 42 mg/m2 idarubicin. Grafts were T cell-depleted using counterflow centrifugation. Donors were HLA-identical siblings. We compared outcome of BMT in 109 patients aged less than 50 (median, 35) years with that of 22 patients with an age of 50 years or more (median, 53 years). For the patients aged <50 years, 2-year probabilities of treatment-related mortality, relapse, survival and leukemia-free survival were 26% (95% CI, 17% to 35%), 26% (95% CI, 17% to 35%), 64% (95% CI, 55% to 73%), and 56% (95% CI, 47% to 65%). For the patients aged > or =50 years, these figures were 13% (95% CI, 0% to 30%), 24% (95% CI, 6% to 42%), 66% (95% CI, 46% to 86%), and 67% (95% CI, 47% to 87%), respectively. Outcome did not differ significantly between the two age groups. TRM was within the range of that reported in the literature for recipients of T cell-depleted grafts. We conclude that T cell-depleted transplantation after a conditioning regimen that was intensified with the addition of idarubicin is feasible in patients aged > or =50 years. For this age group of patients, results of nonmyeloablative regimens should be compared with that obtained with T cell-depleted grafts.

Allogeneic bone marrow transplantation for leukemia with marrow grafts treated by counterflow centrifugation.

Eighty consecutive patients were transplanted with human leukocyte antigen (HLA)-identical sibling marrow for acute myelogenous leukemia (AML, N = 29), acute lymphoid leukemia (ALL, N = 23), or chronic myelogenous leukemia (CML, N = 28). Donor marrow was depleted of lymphocytes using counterflow centrifugation. Median age of the recipients was 31 years. Pretransplant conditioning consisted of cyclophosphamide and fractionated total body irradiation (TBI). Graft failure occurred in 4 of 77 evaluable patients (5%). The probability of acute graft-versus-host disease (GVHD) > or = grade 2 at day 100 after transplantation was 15%. The projected 3-year estimate of extensive chronic GVHD was 12%. The projected 3-year probability of relapse was 30% in transplants for AML in first complete remission (CR1), 35% after transplantation for ALL in CR1, and 38% after transplantation for CML in first chronic phase (CP1). The projected 3-year probability of leukemia-free survival (LFS) was 56% after transplantation for AML-CR1, 42% in patients transplanted for ALL-CR1, and 49% after transplantation for CML-CP1. The chance of relapse was significantly reduced in a cohort of 72 standard risk patients conditioned with a regimen intensified by the addition of anthracyclines. This resulted in DFS at 4 years after BMT of 63% compared to 39% in a historical control group. Enrichment of the donor marrow with NK-cells did not increase the incidence of GVHD, but did neither decrease the relapse rate after BMT. In bone marrow transplantation for leukemia, counterflow centrifugation is a useful technique for the prevention of GVHD. Further efforts should be made to reduce relapse-rate, particularly in high risk patients.

Clonal predominance of cytomegalovirus-specific CD8+ cytotoxic T lymphocytes in bone marrow recipients.

After lymphocyte-depleted BMT, CD8+ T cells have been expanded to or above normal levels in 45% of the recipients within 3 months. The mechanisms underlying proliferation of donor-derived CD8+ T cells after BMT are still unclear. We investigated whether these CD8+ T cells proliferate in response to specific antigens by determination of TCR clonality and whether these cells exert specific cytotoxicity. PCR analysis of TCR-gamma gene rearrangements showed a marked clonal predominance in CD8+ T cells of recipients with a high number of these cells. Strong association between expansion of CD8+ T cells and CMV infection suggests involvement of CMV antigens. Therefore, we examined CMV-specific cytotoxicity of freshly isolated CD8+ T cells of two BMT recipients with clonal expansion after the onset of CMV infection. CD8+ T cells exerted HLA-restricted cytotoxicity directed against CMV-infected fibroblasts indicating that CMV stimulates proliferation. The majority of CD8+ T cells in these recipients expressed CD57. We demonstrated that TCR clonality was irrespective of CD57 expression. Both CD8+CD57+ and CD8+CD57- T cells showed significant HLA-restricted CMV-specific cytotoxicity. These studies strongly suggest that CMV antigens can induce expansion of clonal CD8+ T cells after BMT.

Addition of ATG to the conditioning regimen is a major determinant for outcome after transplantation with partially lymphocyte-depleted grafts from voluntary unrelated donors.

We retrospectively analysed the outcome of voluntary unrelated donor (VUD)-SCT in 56 patients after conditioning without or with ATG. All received partially lymphocyte-depleted grafts. Four of 17 patients (24%) who were not given ATG rejected their grafts, as did one of 33 (3%) conditioned with ATG (P=0.02). The incidences of acute graft-versus-host disease grade III/IV were 29 and 6%, respectively (P=0.02), and probabilities of 1-year transplant-related mortality were 64% (95% CI, 44-84%) and 27% (95% CI, 12-42%), respectively (P=0.004). Projected at 3 years, probability of survival was 18% (95% CI, 2-34%) after conditioning without ATG and 60% (95% CI, 43-70%) after conditioning with ATG (P=0.002). Probabilities of disease-free survival (DFS) were 18% (95% CI, 2-34%) and 45% (95% CI, 27-63%), respectively (P=0.005). Patients who did not receive ATG had a probability of current DFS of 18% (95% CI, 3-34%) and this was 60% (95% CI, 43-77%) for the patients conditioned with ATG (P<0.001). We conclude that the addition of ATG to the conditioning regimen is associated with a significantly more favourable outcome in recipients of partially T-cell-depleted grafts from VUDs.

Survival in first or second remission after lymphocyte-depleted transplantation for Philadelphia chromosome-positive CML in first chronic phase.

We studied the outcome of BMT in 38 consecutive CML patients in CP1 who received transplants depleted of lymphocytes using counterflow centrifugation. In all patients the conditioning regimen was intensified by the addition of anthracyclines. Donors were HLA, MLC-identical siblings. Six patients (16%) died within 6 months. All 37 patients with a follow-up of more than 0.5 months engrafted and only one (3%) suffered from acute GVHD > or = grade 3. Chronic GVHD was evaluable in 33 patients and was extensive in six (18%). The projected 5-year probabilities of hematologic, cytogenetic and molecular relapse were 30% (95% confidence interval (CI), 10-49%), 35% (95% CI, 14-56%), and 34% (95% CI, 13-55%), respectively. The projected 5-year probability of survival was 68% (95% CI, 50-86%). Projected at 5 years, probabilities of leukemia-free survival (LFS) in hematologic, cytogenetic and molecular remission were 55% (95% CI, 37-73%), 51% (95% CI, 32-69%), and 51% (95% CI, 32-70%), respectively. All patients with relapse but one who relapsed in blastic phase were treated with retransplantation (n = 1) or with the infusion of lymphocytes (n = 6). Six patients regained second hematologic remission and five entered second cytogenetic and molecular remission. Including these patients, the probability of survival in first or second hematologic remission at the end of follow-up was 68% (95% CI, 50-86%). The probabilities of survival in first or second cytogenetic and molecular remission at the end of follow-up were both 61% (95% CI, 42-80%). We advocate revaluation of T cell depletion of donor marrow for patients with CML-CP1, especially for those at high risk of developing GVHD.