A phase I/II trial of recombinant human interleukin-6 in patients with aplastic anaemia

In a phase I/II study, 11 patients with marrow failure (10 with acquired aplastic anaemia and one with pancytopenic Fanconi anaemia) were treated with recombinant human interleukin-6 (rhIL-6) to assess the safety and tolerability of rhIL-6 and its effects on peripheral blood counts, bleeding complications and transfusion requirements. All patients with acquired aplastic anaemia were refractory to immunosuppressive treatment or had relapsed after immunosuppressive therapy and were not bone marrow transplantation candidates. Recombinant hIL-6 was to be given as a once-daily subcutaneous injection for 28 d at doses ranging from 0.5 to 5.0 micrograms/kg. After an observation period of 2 weeks, five patients received a second treatment course of 28 d. Only one patient had a sustained increase in platelet count from 18,000 to 72,000/microliters. Bleeding occurred in four patients and caused premature discontinuation of rhIL-6 therapy in three patients. A deterioration of pre-existing anaemia was observed in nine patients. No significant changes of leucocyte counts were observed during the first cycle. During the second cycle the peripheral blood monocyte counts decreased significantly. No significant changes in bone marrow cellularity were observed. Recombinant hIL-6 induced a dose-dependent increase in acute-phase reactants in all patients. Other adverse events included fever, headache, arthralgia, tachycardia and hypertension. In conclusion, rhIL-6 given alone at low doses does not increase platelet counts in the majority of patients with aplastic anaemia and can precipitate a sudden worsening of pre-existing anaemia and thrombocytopenia. This study was discontinued prematurely on account of the toxicity of rhIL-6 seen in patients with aplastic anaemia.

Successful therapy with donor buffy coat transfusions in patients with relapsed chronic myeloid leukemia after bone marrow transplantation is associated with high frequencies of host-reactive interleukin 2-secreting T helper cells

Six patients treated for relapsed chronic myeloid leukaemia after allogeneic bone marrow transplantation with donor buffy coat transfusions were investigated. In the 5 patients who achieved molecular remission high frequencies of host-reactive interleukin 2-secreting T helper cell precursors (Th-p) were detectable by limiting dilution analysis. In four of the patients the presence of Th-p was associated with a clinical syndrome similar to transfusion GVHD suggesting a T cell response to minor histocompatibility antigens (minor H) expressed by both malignant haemopoiesis and host tissues. In the fifth responding patient no GVHD or bone marrow hypoplasia was observed. The nature of the antigens recognised by these donor Th-p remains unknown. No host-reactive Th-p were detectable in the non-responder and host-reactive cytotoxic T cell precursors (CTL-p) were not consistently detectable in the responding patients.

Presence of host-specific interleukin 2-secreting T helper cell precursors correlates closely with active primary and secondary chronic graft-versus-host disease

We investigated the role of interleukin 2 (IL-2)-secreting T helper cell precursors (Th-p) in primary and secondary chronic graft-versus-host disease (GVHD). Twelve patients with chronic GVHD (8 primary and 4 secondary chronic GVHD) and 8 patients without chronic GVHD were investigated using a sensitive limiting dilution assay. High frequencies of host-reactive interleukin 2-secreting T helper cell precursors were detectable in all patients with chronic GVHD irrespective of the mode of onset. Host-reactive IL-2-secreting T helper cell precursors disappeared in patients whose GVHD resolved. Host-reactive IL-2-secreting T helper cell precursors were never found in the control patients without chronic GVHD. Host-reactive cytotoxic T cell precursors (CTL-p) were not consistently detectable in patients with chronic GVHD and were occasionally found in patients without GVHD. No autoreactive IL-2-secreting T helper cell precursors or cytotoxic T cell precursors were detectable in either group. The absence of autoreactive IL-2-secreting T helper cell precursors in patients was confirmed by clonal specificity analysis in 4 patients. These data suggest a role for host-reactive IL-2-secreting T helper cell precursors in the initiation and maintenance of chronic GVHD as previously shown for acute GVHD.

In vivo/ex vivo T cell depletion reduces the morbidity of allogeneic bone marrow transplantation in patients with acute leukaemias in first remission without increasing the risk of treatment failure: comparison with cyclosporin/methotrexate

We have performed a non-randomised GVHD prophylaxis trial comparing cyclosporin/methotrexate with in vivo/ex vivo T cell depletion with the monoclonal antibodies Campath 1G/1M in patients with acute leukaemias in first complete remission. We observed significantly less acute and chronic GVHD, neutropenic fever and severe mucositis in the T cell depletion group. The incidence of graft rejection and relapses was no higher than in the cyclosporin/methotrexate group. There is a trend in favour of improved disease-free survival in the in vivo/ex vivo T cell depletion group (80% vs. 62%).

Anticoagulant-induced pseudothrombocytopenia and pseudoleucocytosis

Pseudothrombocytopenia (PTP) is the phenomenon of falsely low platelet counts due to in vitro platelet clumping in the presence of platelet autoantibodies and anticoagulants. We assessed anticoagulant-dependence, time course of platelet counts and impact of different counter devices on the phenomenon. Blood of 10 persons with previously recognized pronounced EDTA-dependent PTP was collected into 7 different anticoagulants and counted after different intervals in parallel in a Coulter T540 and a Coulter STKS counter and by phase contrast microscopy. With the Coulter T540 model PTP was most pronounced in blood samples anticoagulated with EDTA, Na-oxalate or Na-citrate. In the STKS counter EDTA, heparin and oxalate presented as the worst anticoagulants. The time course of platelet counts was significantly different between the two counters. Our results demonstrate that PTP is not restricted to EDTA, but is also present with other anticoagulants. In contrast, pseudoleucocytosis was observed only in EDTA-anticoagulated blood in the Coulter T540 device. We investigated the expression of platelet integrins and activation antigens on platelets of persons with anticoagulant-dependent PTP and in healthy controls without PTP. In the presence of EDTA the expression of GpIIb/IIIa was significantly reduced in the PTP subjects compared to control. Activation antigens CD62, CD63 and thrombospondin-antigen were upregulated in the presence of EDTA. These alterations in the expression of platelet antigens could also be induced on platelets of normal donors by incubation with sera of PTP subjects and EDTA.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo/ex vivo T cell depletion for GVHD prophylaxis influences onset and course of active cytomegalovirus infection and disease after BMT

Combined in vivo/ex vivo T cell depletion is effective in the prophylaxis of graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation (BMT), but influences the occurrence of active cytomegalovirus (CMV) infection and disease. Twenty nine patients receiving a T cell-depleted marrow graft (Campath-1M) after intravenous application of the monoclonal antibody Campath-1G prior to conditioning were monitored for virus shedding and antigenaemia from day -7 to day +100. In seropositive patients in this group active CMV infection occurred more frequently (10 of 16) and much earlier (nine of 10 until day +21) than in 27 seropositive patients (10 of 27, P < 0.02) receiving cyclosporin A and methotrexate (CsA/MTX). Early active CMV infection after in vivo/ex vivo T cell depletion correlated strictly with an early increase in blood lymphocyte counts (P < 0.01), with predominance of NK cells and/or CD8+ T cells. Three cases of very early interstitial pneumonitis (IP) occurred after in vivo/ex vivo T cell depletion compared with none in the CsA/MTX group. IP was fatal in the only patient with early active CMV infection, who remained lymphocytopenic till death on day +31. This may indicate that an early immune response against CMV is possible and essential for favourable clinical outcome.

A pathogenetic link between aplastic anemia and paroxysmal nocturnal hemoglobinuria is suggested by a high frequency of aplastic anemia patients with a deficiency of phosphatidylinositol glycan anchored proteins

The clinical interrelationship between paroxysmal nocturnal hemoglobinuria (PNH) and aplastic anemia (AA) promoted a search for a pathogenetic link. Since the molecular defect in PNH is a failure to express phosphatidylinositol glycan-anchored proteins (PIG-AP), we investigated whether this defect could also be demonstrated on peripheral blood cells of patients with typical AA. Quantification of the expression of PIG-AP was performed by flow cytometry using the monoclonal antibodies (MAbs) CD16 and CD66b for granulocytes, CD14 and CD48 for monocytes, CD48 and CD52 for lymphocytes, and CD55 and CD59 for erythrocytes. We analyzed cells from 52 patients with acquired AA. A PIG-AP-defective population was identified in 27 of 52 patients (52%) in at least one cell lineage. Granulocytes were involved in 25 of 27, monocytes in 18 of 25, lymphocytes in seven of 27, and erythrocytes in seven of 27 AA patients who were affected by a PIG-AP deficiency. The response rate to standard immunosuppressive therapy was significantly higher in the group of patients without a PIG-AP-deficient population than in patients with a PIG-AP-deficient population in at least one cell lineage (85.7 vs. 30.4%; p < 0.0003). Our results demonstrate that on the basis of PIG-AP expression, the proportion of AA patients who show features of typical AA along with a PNH phenotype is substantially higher than previously recognized. The pattern of PIG-AP expression might identify subgroups of AA patients who differ in the underlying mechanism as well as in the course of their disease.

Randomized comparison of interferon-alpha with busulfan and hydroxyurea in chronic myelogenous leukemia. The German CML Study Group

As curative bone marrow transplantation is available only to a minority of patients with chronic myelogenous leukemia (CML), drug therapy remains of central interest. Several nonrandomized studies have suggested that interferon-alpha (IFN) may prolong survival in CML. In a randomized multicenter study the influence of IFN versus busulfan or hydroxyurea (HU) on survival of Philadelphia-positive (Ph+) CML was examined. A total of 513 Ph+ patients were randomized for treatment as follows: 133 for IFN, 186 for busulfan, and 194 for HU. IFN-treated CML patients have a significant survival advantage over busulfan-treated (P = .008), but not over HU-treated patients (P = .44). The longer survival is due to slower progression to blast crisis. Median survival of IFN-treated patients is 5.5 years [5-year survival, 59%; 95% confidence interval (CI), 48%-70%], of busulfan-treated patients, 3.8 years (5-year survival, 32%; CI, 24%-40%), and of HU-treated patients, 4.7 years (5-year survival, 44%; CI, 36%-53%). Patients who continue on IFN survive longer than those in whom IFN is discontinued before blast crisis (P = .007). Complete hematologic IFN-responders have a survival advantage over partial responders or nonresponders (P = .02). Cytogenetic IFN-responders have no significant survival advantage over nonresponders (P = .2). Patients who attain white blood cell (WBC) counts of 10 x 10(9)/L or less have a survival advantage in the IFN (P = .007) and HU (P = .05) groups. Whereas toxicity in the IFN group was considerably higher than in the busulfan or HU groups, long-lasting cytopenias necessitating discontinuation of therapy as observed with busulfan have not been seen with IFN or HU. The problems of conventional prognostic scores (Sokal's score, Score 1) that we observed in IFN-treated patients support the idea that IFN changes the natural course of CML. We conclude that, with regard to survival of CML in the chronic phase, IFN is superior to busulfan and as effective as HU. Whether and to what extent IFN is superior to HU appears to depend, at least in part, on the degree of WBC suppression by HU-therapy and on the risk profile of the patients.

Acute lymphoblastic leukemia in patients over 59 years of age. Experience in a single center over a 10-year period

We report data of 29 consecutive patients aged 60 years or older with newly diagnosed acute lymphoblastic leukemia (ALL) treated at a single center between 1983 and 1992. Immunophenotyping was performed in 26 patients. According to the immunological classification used at the time of diagnosis, 14 had common-ALL, two had T-ALL, six had null-ALL, three had myeloid antigen-positive ALL with both lymphoid and myeloid markers, and one had B-ALL. One patient died before therapy could be instituted. Twenty-four patients received intensive induction chemotherapy. Nine of these patients died during the first 8 weeks, eight due to infections and one due to liver failure after asparaginase. In 14 of the remaining patients treated intensively, scheduled treatment was discontinued prematurely due to treatment-related toxicity and was replaced by milder chemotherapy. Four patients aged 75-77 years were treated with vincristine and prednisone. Only one patient who completed a whole study protocol survived more than 5 years. Twelve of the 28 patients treated with chemotherapy achieved complete remissions. The median survival was 5 months (range 1-103+). Median survival in patients with CR was 9.0 months. Actuarial survival is 3%. Our data demonstrate a poor prognosis in ALL patients over 59 years of age. The reasons were a high mortality during intensive induction therapy due to toxicity of treatment and a short remission duration.

Prospective randomized clinical study in general surgery comparing a new low molecular weight heparin with unfractionated heparin in the prevention of thrombosis

A prospective, randomized, controlled clinical trial was performed comparing the antithrombotic efficacy of the low molecular weight heparin LMWH 21-23, (Braun) with an unfractionated heparin in elective general surgical patients over an observation period of 7 postoperative days. A total of 230 patients were admitted: 103 (group I) received low molecular weight heparin and 100 (group II) low-dose unfractionated heparin treatment given subcutaneously. In group I 41 patients (46%) were operated on for malignant disease and in group II 54 patients (54%). Due to the large amount of great abdominal procedures the intra- and perioperative application of hydroxyethyl starch was allowed for volume substitution. None of the patients died due to fatal pulmonary embolism. In group I four patients revealed positive 125I-labeled fibrinogen uptake (3.9%); two patients belonged to the hydroxyethyl starch subgroup. In group II five patients displayed a positive fibrinogen uptake (5%); two belonged to the hydroxyethyl starch subgroup. The results of the hemostaseological investigations (e.g., prothrombin time, activated partial thromboplastin time, thrombin clotting time, fibrinogen, antithrombin III, protein C, plasminogen, alpha 2-antiplasmin, tissue-type plasminogen activator, plasminogen activator inhibitor) revealed no statistically significant differences between groups I and II or their subgroups, although a tendency to prolonged clotting times was observed. The antifactor Xa activity values, however, displayed a statistically significant difference between the two groups (P < 0.05). The antifactor Xa activity measured up to 0.16 U/ml for the low molecular weight heparin (group I) and 0.05 U/ml for the unfractionated heparin (group II) in the postoperative period.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum erythropoietin and serum transferrin receptor levels in aplastic anaemia

Serum erythropoietin (EPO) and soluble transferrin receptor levels were serially measured in 74 patients with aplastic anaemia (AA). As control groups we investigated healthy controls (n = 24) and patients with iron-deficiency (n = 23) or haemolytic anaemia (n = 16). There was a significant negative correlation of log EPO on haematocrit both in AA patients and in the anaemic control group. However, for the same degree of anaemia, log EPO levels in AA were significantly higher than in iron-deficiency or haemolytic anaemia. EPO levels at diagnosis did not correlate with severity of aplastic anaemia, nor did they predict outcome after immunosuppression. During immunosuppressive treatment of AA with anti-thymocyte globulin and cyclosporine A, EPO levels were significantly lower compared with pre-treatment values without a corresponding change in haematocrit. This impaired EPO response to anaemia during immunosuppression might affect recovery of erythropoiesis. In AA patients, EPO levels declined with haemopoietic recovery. However, compared with normal controls, EPO levels in remission patients were still higher with respect to their haematocrit. Results of this study argue against the model of a simple feedback regulation of EPO via hypoxic anaemia. Our data support the hypothesis that cytokines and the erythropoietic progenitor pool are involved in the regulation of EPO production. The results illustrate that serial measurements of EPO along with therapeutic interventions are necessary to identify patients who might benefit from treatment with exogenous recombinant human EPO.

High-titre interferon-alpha antibodies in a patient with chronic graft-versus-host disease after allogeneic bone marrow transplantation

In a patient undergoing allogeneic BMT for chronic phase CML, de novo chronic GVHD developed within 80 days after transplantation. Eighteen months post-BMT, high serum levels of neutralizing interferon-alpha (IFN-alpha) antibodies were detected, which persisted despite continuous immunosuppressive treatment. The antibodies were of oligoclonal or polyclonal origin, predominantly of the IgG1 type, and reacted broadly with various human IFN-alpha types, including the patients endogenous IFN-alpha, but failed to recognize natural IFN-beta and recombinant IFN-gamma. Pathogenesis and clinical impact of the IFN-alpha antibodies are unknown. Antibodies of cytokines are a novel class of autoantibodies that may develop after allogeneic BMT and interfere with cytokine homeostasis and immune regulation.

Parvovirus B19 as a cause of acquired chronic pure red cell aplasia

Parvovirus B19 infection causes chronic anaemia in immunodeficient individuals by selective suppression of erythropoiesis. The bone marrow morphology is characteristic of pure red cell aplasia (PRCA). To determine the frequency of B19-induced PRCA we retrospectively analysed a series of 57 PRCA patients. B19 DNA was present in serum of eight patients (14%) and could be extracted from bone marrow aspirate slides from five of these patients. Recent exposure to the virus was confirmed by the presence of anti-B19 IgM in sera from four and by the finding of giant pronormoblasts in marrow aspirates from five of the B19 DNA-positive patients. The sensitivities of anti-B19 IgM and of giant pronormoblasts were only 50% and 63%, respectively; specificities were 90% and 92%. Unexpectedly, PRCA in two B19 DNA-positive patients remitted after antilymphocyte globulin or cyclosporin A therapy, suggesting that the clinical course of B19-induced PRCA may be indistinguishable from other forms of PRCA. As therapy with immunoglobulin is uniformly effective for treatment of B19-associated anaemia, our data suggest that all patients with acquired PRCA should be evaluated for evidence of B19 infection. B19 DNA analysis is the most reliable method to demonstrate infection.

CD 54 expression and its role in homotypic aggregation of the blasts of acute myeloblastic leukemias (AML)

CD 54 (ICAM-1) expression was studied on blasts of 13 cases of de-novo AML prior to and after stimulation by interferon-gamma (IFN-gamma). Furthermore, its functional activity was studied by analysis of the influence of CD 54 on homologous interaction of the blasts. Prior to culture only a minority of the blasts displayed CD 54 positivity. Timed incubation of the blasts in RPMI-1640/FCS or serum-free medium 'spontaneously' increased the percentage of CD 54 positive cells in 11/13 cases with a main increase after 24 h. IFN-gamma (500 IU/ml) further enhanced CD 54 positivity in 6/11 cases. In 2/13 cases neither a 'spontaneous' nor an IFN-gamma induced CD 54 upregulation occurred. The homotypic aggregation of the AML blasts paralleled ICAM-1 expression in that (1) in all but the two CD 54 negative cases autologous cluster formation could be detected, (2) IFN-gamma enhanced cluster formation in 5/6 cases in which it had enhanced CD 54 upregulation, (3) incubation of the blasts in the presence of an anti-CD 54 MoAb (clone 84H10) reduced the 'spontaneous' and IFN-gamma induced cluster formation in a majority of the cases. Taken together, ICAM-1 expression on AML blasts is heterogenous with respect to (1) its 'constitutional' expression and (2) its 'spontaneous' and IFN-gamma-induced upregulation, while it seems to be functionally active once expressed on the surface membrane. The reason for the heterogenity, which did not correlate with the FAB subtype, and its importance remain unclear.

Peroxidase expression in acute unclassified leukemias: ultrastructural studies in combination with immunophenotyping

The lineage affinity of 61 cases of acute unclassified leukemias (AUL) was reevaluated by ultrastructural analysis of peroxidase expression (POEM) in combination with immunophenotyping. In 24 cases a significant proportion of the blasts displayed ultrastructural myeloperoxidase (UMPO) and in another 3 cases platelet peroxidase (UPPO) suggesting the allocation of these leukemias to the myeloid or megakaryoblastic lineage. No significant correlation between myeloid surface marker expression and POEM positivity could be detected, while the presence of the CD 19 or CD 24 antigen significantly correlated with POEM negativity. The detection of lymphoid markers on POEM+ blasts indicates, that these leukemias might be derived from bipotential progenitors, which have retained their lymphoid antigens during myeloid differentiation. In one case a bilineage leukemia with a POEM+/CD 19- and a POEM-/CD 19+ population could be identified by immunoelectron microscopical studies (IEM). The remaining 34 AUL cases were POEM negative. Combined data suggest that these cases probably derive from early lymphoid progenitors. Taken together, AUL are heterogenous in presentation and in their cellular origin including a major portion of cases with an unequivocal myeloid differentiation detectable by ultrastructural analysis of myeloperoxidase expression.

Sensitive antiproliferative neutralization assay for the detection of neutralizing IFN-alpha and IFN-beta antibodies

Antibodies to interferon (IFN) may compromise IFN treatment in some patients. In tumor therapy, a critical function of type I IFNs is their antiproliferative effect. For the quantification of neutralizing IFN antibodies we have developed an antiproliferative neutralization assay (APA) based on the reduction of IFN-mediated growth inhibition of Daudi cells by IFN-alpha and IFN-beta antibodies. Proliferation was quantified by [3H]thymidine incorporation, and the neutralizing potency of IFN antibody-positive sera was expressed as the neutralizing titer inhibiting 50% of the antiproliferative activity of 10 IU/ml of IFN (NT50). The APA is easy to perform, reproducible, and more sensitive than a well-established antiviral neutralization assay (AVA). All 30 sera with recombinant IFN-alpha 2a-binding antibodies proved to be neutralizing antibody-positive in the APA whereas seven were scored antibody-negative or uninterpretable in the AVA. The APA is recommended as a second or third line assay for the estimation of the neutralizing potency of spontaneous or treatment-induced IFN-alpha and IFN-beta-specific antibodies.

Low incidence of invasive fungal infections after bone marrow transplantation in patients receiving amphotericin B inhalations during neutropenia

The incidence of invasive fungal infections after bone marrow transplantation (BMT) was analyzed in 303 consecutive marrow graft recipients (allogeneic n = 271, autologous n = 27, syngeneic n = 5). All patients received inhalations with amphotericin B (10 mg twice daily) during neutropenia. The overall incidence of invasive fungal infections within the first 120 days after transplant was 3.6% (11/303; aspergillosis: 6; yeast infection: 5). Four of the 11 cases occurred early, and seven cases were observed after neutrophil recovery and discontinuation of amphotericin B inhalation treatment. Late infection was significantly associated with the development of acute graft-versus-host disease. Four of the 11 infections (early 2/4; late: 2/7) were observed in patients with a history of previous fungal infection. Other patient and treatment characteristics were not helpful in defining potential risk factors. In particular, the incidence of invasive fungal infections did not differ between patients with more or less strict reverse isolation measures. Occasional side effects such as initial mild cough and bad taste were rare, usually disappeared during continued administration, and were in no case the reason for discontinuation of treatment. These data suggest that aerosolized amphotericin B may be a useful, convenient, and efficient prophylactic antifungal regimen in BMT.

Capillary leak syndrome associated with elevated IL-2 serum levels after allogeneic bone marrow transplantation

The pathophysiological mechanisms involved in the development of a spontaneous systemic capillary leak syndrome (CLS) are unknown. In contrast, CLS is a well-known side effect of high-dose interleukin-2 (IL-2) therapy in solid tumors. We report on a patient who developed CLS with high serum levels of endogenous IL-2 under immunosuppressive therapy for chronic graft-versus-host disease (GvHD) after allogeneic bone marrow transplantation (BMT). Generalized edema persisted for 10 weeks. The condition resolved after antibiotic therapy of a septic shock with beta hemolyzing streptococci group A. Thus, a latent infection may alter cytokine homeostasis and may cause CLS in BMT patients.

Interferon-alpha and donor buffy coat transfusions for treatment of relapsed chronic myeloid leukemia after allogeneic bone marrow transplantation

Eight patients with chronic myeloid leukemia relapse after allogeneic BMT were treated with IFN-alpha and buffy coat transfusions (BC) of the bone marrow donor. The antileukemic effect of this treatment was directly demonstrated in 4 patients by the disappearance of Philadelphia chromosome-positive metaphases or the loss of detectable BCR-ABL transcripts by polymerase chain reaction. In 2 patients in whom cytogenetic or polymerase chain reaction analysis was not performed, a change in hemopoietic chimerism with recurrence of donor-type hemopoiesis was demonstrated. Two patients, both treated in advanced stages of hematological relapse after BMT, did not respond. However, severe side effects of the treatment were observed: graft-versus-host disease (GVHD) occurred in 5 patients. Two of these patients progressed to severe chronic GVHD and 1 patient ultimately died of this complication. GVHD occurred in 5 of the 6 responding patients; one patient responded without developing clinical symptoms of GVHD. Six patients developed bone marrow hypoplasia after IFN/BC treatment, and pancytopenia occurred in 4 patients. None of these 4 patients recovered spontaneously and 2 patients died of complications of pancytopenia (cerebral bleeding, infection). Our results demonstrate that treatment of chronic myeloid leukemia relapse with IFN and BC transfusions is highly effective in patients with relapse in chronic phase. The occurrence of GVHD and pancytopenia, however, resulted in a high treatment-associated morbidity and mortality. Whereas a response to treatment was observed in 1 patient without GVHD, indicating that GVHD and a graft-versus-leukemia effect may be clinically separable, bone marrow hypoplasia occurred in all responding patients.