Efficient retrovirus-mediated transduction of primitive human peripheral blood progenitor cells in stroma-free suspension culture

Retroviral transduction of hematopoietic cells has resulted in unsatisfactory gene marking in clinical studies. Since cytokine-stimulated stem cells have engrafted poorly in animal models, we investigated phenotypic changes during culture of peripheral blood progenitor cells (PBPC). Human CD34(+) HLA-DR(low) cells, immunomagnetically separated from PBPC collections, were found to extrude rhodamine-123, which is characteristic for primitive hematopoietic cells. Cells were grown in suspension cultures supplemented with cytokines. While interleukin-3-containing factor combinations promoted cell proliferation they caused loss of rhodamine-123 extrusion and reduced the frequencies of cobblestone area-forming cells (CAFC). Several other cytokines failed to stimulate cell divisions, which are required for retroviral transduction. A combination including Flt-3 ligand (FL), interleukin-6 and stem cell factor (SCF) preserved an immature phenotype for 5 to 6 days and stimulated cell divisions, which was improved upon addition of leukemia inhibitory factor and interleukin-11. Furthermore, the CAFC frequency among cells treated with these cytokines was increased as compared with widely used cocktails containing interleukin-3, interleukin-6 and SCF. Rhodamine-123 appeared to be a particularly sensitive indicator for differentiation of PBPC. For analysis of gene transfer, amphotropic retroviruses conferring an MDR1 cDNA were added repeatedly for 6 days to cytokine-treated PBPC stroma-free cultures. Proviral cDNA was detected by polymerase chain reaction in 68% of cobblestone areas derived from CD34(+)HLA-DR(low) cells that had been exposed to Flt-3 ligand, interleukin-6 and SCF. In summary, conditions were identified that facilitate efficient transduction of early PBPC with amphotropic retroviruses while preserving a primitive phenotype for extended periods.

Current results of bone marrow transplantation in patients with acquired severe aplastic anemia. Report of the European Group for Blood and Marrow transplantation. On behalf of the Working Party on Severe Aplastic Anemia of the European Group for Blood and Marrow Transplantation

We have analyzed 2,002 patients grafted in Europe between 1976 and 1998 from an identical twin (n = 34), from an HLA-identical sibling (n = 1,699) or from an alternative donor (n = 269), which included unrelated and family mismatched donors. The proportions of patients surviving in these three groups are, respectively, 91, 66 and 37%: major causes of failure were acute graft-versus host disease (GvHD) (11%), infection (12%), pneumonitis (4%), rejection (4%). In multivariate Cox analysis, factors predicting outcome were patient's age (p < 0.0001), donor type (p < 0.0001), interval between diagnosis and bone marrow transplantation (BMT) (p < 0.0005), year of BMT (p = 0.0005) and female donor for a male recipient (p = 0.02). Patients were then divided in two groups according to the year of BMT: up to or after 1990. The overall death rate dropped from 43 to 24% (p < 0.00001). Improvements were seen mostly for grafts from identical siblings (from 54 to 75%, p < 0.0001), and less so for alternative-donor grafts (from 28 to 35%; p = 0.07). Major changes have occurred in the BMT protocol: decreasing use of radiotherapy in the conditioning regimen (from 35 to 24%; p < 0.0001) and increasing use of cyclosporin (with or without methotrexate) for GvHD prophylaxis (from 70 to 98%; p < 0.0001). In conclusion, the outcome of allogeneic BMT for patients with severe aplastic anemia has considerably improved over the past two decades: young patients, grafted early after diagnosis from an identical sibling, have currently an over 80% chance of long-term survival. Transplants from twins are very successful as well. The risk of complications with alternative donor transplants is still high.

Paroxysmal nocturnal haemoglobinuria: a replacement of haematopoietic tissue?

Acquired somatic mutations of the PIG-A gene lead to deficient expression of glycosyl-phosphatidyl-inositol-anchored proteins (GPI-AP) by haematopoietic cells and play a causative role in the pathogenesis of paroxysmal nocturnal haemoglobinuria (PNH). However, PIG-A mutations do not explain how the defective PNH clone can expand. It was hypothesized that a selection process conferring a relative advantage to the GPI-AP-deficient population is required. Since GPI-AP-deficient cells are also detectable in a substantial proportion of patients with otherwise typical aplastic anaemia (AA), the mechanisms inducing bone marrow failure might selectively spare the GPI-deficient cells. In order to examine the growth characteristics of GPI-AP-deficient cells in more detail, we performed repeated analyses of GPI-AP expression on peripheral blood cells in 41 patients with AA. We observed four patterns of the course of GPI-AP-deficient populations: (1) 13 patients showed normal expression of GPI-AP in the first analysis and in at least two follow-up studies at a median time of 709 days after the first analysis. (2) Secondary evolution of a GPI-AP-deficient population was a rare event. Only 4 patients with initially normal GPI-AP expression developed a GPI-AP-deficient population during follow up after immunosuppressive treatment. (3) Persistence of GPI-AP-deficient cells was observed in 16 patients during a median follow-up time of 774 days. However, in some patients, the size of the GPI-AP-deficient population increased substantially. (4) Disappearance of a GPI-AP-deficient population was observed in 8 patients. The time course of GPI-AP expression in relation to the treatment suggests that therapeutic interventions might modulate the ratio of normal versus GPI-AP-deficient haematopoiesis. Overall, these data argue against an 'absolute growth advantage' of GPI-AP-deficient cells. Our data are consistent with the hypothesis that haematopoietic failure caused by damage to normal haematopoiesis allows the outgrowth of a GPI-AP-deficient population. Thus, in at least some patients GPI-AP-deficient cells might pre-exist at a very low percentage and replace haematopoiesis after an insult to the normal cells.

CD34 selected alloPBSCT and adoptive immunotherapy

To circumvent aGVHD in the early phase after allogeneic stem cell transplantation but to provide GVL activity later on, we performed alloPBSCT with CD34+ selected grafts followed by delayed add-back of CD3+ T cells. Ten consecutive patients having an HLA-identical sibling donor were enrolled on to this trial. Four patients were in first CR of high-risk ALL, another four in first CR of AML, one was in second myeloid blast crisis of CML, and one was in PR of relapsed NHL. Conditioning consisted of 2 x 60 mg/kg CY plus 12 Gy TBI. G-CSF (Filgrastim) mobilized peripheral cells were CD34+ selected using the Isolex 300i system in nine patients and the CliniMacs system in one. Median CD34+ purity was 86%. A median of 2.8 x 10(6)/kg CD34+ cells were transplanted. The number of CD3+ cells in the allografts was 5.7 x 10(4)/kg (median) after Isolex 300i, and 0.2 x 10(4)/kg after CliniMacs. All patients received G-CSF (Filgrastim) and engrafted rapidly. Standard-dose CsA was administered, and until day +60 no aGVHD occurred. At that time point, seven patients received 2 x 10(6)/kg CD3+ cells while CsA had been tapered to 50% of the starting dose. One of these patients died after a second T cell boost given on day +90 without concomitant immunosuppression due to grade IV intestinal aGVHD. Three others developed cutaneous cGVHD. Taken together, T cell depletion by CD34+ selection does not impair rapid engraftment in the HLA-identical sibling donor setting. Using standard-dose CsA the risk for acute GVHD seems to be minimized. Add-back of 2 x 10(6)/kg CD3+ cells on day +60 with CsA protection is feasible. However, whether this is the optimal time point and number of T cells remain to be further elucidated.

Serum erythropoietin and thrombopoietin levels in patients with essential thrombocythaemia

In 40 patients with essential thrombocythaemia (ET) serum erythropoietin (EPO) and thrombopoietin (TPO) concentrations were determined and compared with the EPO and TPO values of a healthy control group. The mean EPO serum concentration for 24 control patients was 9.4 mU/ml +/- 3.7 (range 2-17.9), for 32 untreated ET patients at diagnosis 6.6 mU/ml +/- 7.6 (range 0.5-44.3) and for 8 ET patients treated with cytoreduction 14.1 mU/ml +/- 8.0 (range 4.5-26.1). Serum EPO levels in untreated ET patients at diagnosis were significantly lower compared with serum EPO levels in healthy control patients (p=0.002). Serum EPO levels in treated ET patients were not different from serum EPO levels in healthy controls (p=0.13) but were significantly higher compared with untreated ET patients (p=0.003). Serum TPO levels were determined in 18 of 40 ET patients, the mean TPO serum concentration was 211 pg/ml +/- 109 (range 62,5-345). The mean TPO serum concentration for 10 untreated ET patients at diagnosis was 162 pg/ml +/- 87 (range 62,5-302) and for 8 ET patients who had received cytoreductive treatment 272 pg/ml +/- 106 (range 96-345), respectively (p=0.04). Both serum TPO levels for treated and untreated ET patients were significantly higher (p<0.001) compared with serum TPO levels for healthy controls. The results of our study suggest a difference in the regulation of serum EPO and TPO in patients with ET. While the mean serum EPO level is decreased in untreated ET patients, the corresponding mean serum TPO level is increased. Treatment with cytoreduction, results in normalisation of the mean serum EPO level, whereas the mean TPO serum level remains elevated.

Treatment of acquired severe aplastic anemia: bone marrow transplantation compared with immunosuppressive therapy--The European Group for Blood and Marrow Transplantation experience

Patients with severe aplastic anemia (SAA) can be successfully treated with bone marrow transplantation (BMT) or immunosuppressive therapy (IS). The current outcome using both forms of therapy among 3,669 patients treated in Europe between 1976 and 1998 is reviewed. Significant progress has been made and the overall risk of failure is now low, with survival rates greater than 80% for both treatments. Chronic graft-versus-host disease (GvHD) remains a problem for BMT patients, and carries a high risk of lethal complications. On the other hand, IS patients are exposed to late failure due to relapse or clonal/malignant diseases. First-line BMT from identical siblings is compared with IS therapy in an intent-to-treat analysis of 1,765 patients, regardless of subsequent transplant status. The outcome of SAA patients has improved considerably over time and is influenced by patient variables such as severity of the disease and age, but also by the choice of the initial treatment.

The tyrosine kinase NPM-ALK, associated with anaplastic large cell lymphoma, binds the intracellular domain of the surface receptor CD30 but is not activated by CD30 stimulation

The heterogenous group of anaplastic large cell lymphomas (ALCLs) is characterized by expression of the Ki-1/CD30 antigen, a member of the tumor necrosis factor receptor superfamily. About 40 to 50% of cases diagnosed as ALCL contain a specific chromosomal rearrangement, t(2;5)(p23;q35), resulting in expression of the chimeric tyrosine kinase NPM-ALK. As NPM-ALK-positive lymphomas define a distinct subtype within the group of ALCL, the chimeric protein might be responsible for certain pathogenetic and clinicopathologic characteristics. To better elucidate the function of NPM-ALK, we investigated a possible mechanism for regulation of its activity. We demonstrate that NPM-ALK specifically binds to the intracellular domain of the cytokine receptor CD30. In vitro binding assays revealed that the ALK portion of NPM-ALK mediates interaction of the two proteins. Stimulation of the CD30 receptor by cross-linking with immobilized anti-CD30 antibody results in complete growth inhibition of Karpas 299, an NPM-ALK-positive ALCL cell line, but does not alter proliferation of HDLM-2, a Hodgkin's lymphoma-derived cell line lacking t(2;5). Western blot analysis of coimmunoprecipitated CD30 and NPM-ALK proteins from stimulated Karpas 299 cells showed that the interaction of the proteins is not modified by stimulation. Activation of CD30 neither enhanced NPM-ALK activity measured by autophosphorylation of the chimeric tyrosine kinase nor phosphorylation of phospholipase C-gamma, an NPM-ALK substrate. We conclude that NPM-ALK is not stimulated by CD30 activation, but exists as a constitutively hyperactivated protein. Interaction with CD30 may extend the subcellular localization of NPM-ALK to the microenvironment of membrane-associated proteins.

Prospective randomized multicenter study comparing cyclosporin alone versus the combination of antithymocyte globulin and cyclosporin for treatment of patients with nonsevere aplastic anemia: a report from the European Blood and Marrow Transplant (EBMT) Severe Aplastic Anaemia Working Party

We report the results of the first prospective randomized multicenter study of immunosuppressive treatment in patients with previously untreated nonsevere aplastic anemia (AA) as defined by a neutrophil count of at least 0.5 x 10(9)/L and transfusion dependence. Patients were randomized to receive cyclosporin (CSA) alone or the combination of horse antithymocyte globulin ([ATG] Lymphoglobuline; Merieux, Lyon, France) and CSA. The endpoint of the study was the hematologic response at 6 months. One hundred fifteen patients were randomized and assessable with a median follow-up period of 36 months; 61 received CSA and 54 ATG and CSA. In the CSA group, the percentage of complete and partial responders was 23% and 23%, respectively, for an overall response rate of 46%. A significantly higher overall response rate of 74% was found in the ATG and CSA group, with 57% complete and 17% partial responders (P =. 02). Compared with CSA alone, the combination of ATG and CSA resulted in a significantly higher median hemoglobin level and platelet count at 6 months. Fewer patients required a second course of treatment before 6 months due to a nonresponse. In the CSA group, 15 of 61 (25%) patients required a course of ATG before 6 months because of disease progression, compared with only 3 of 54 (6%) in the ATG and CSA group. The survival probabilities for the two groups were comparable, 93% (CSA group) and 91% (ATG and CSA group), but at 180 days, the prevalence of patients surviving free of transfusions, which excluded patients requiring second treatment because of nonresponse, death, disease progression, or relapse, was 67% in the CSA group and 90% in the ATG and CSA group (P =.001). We conclude that the combination of ATG and CSA is superior to CSA alone in terms of the hematologic response, the quality of response, and early mortality, and a second course of immunosuppression is less frequently required.

Effectiveness of immunosuppressive therapy in older patients with aplastic anemia. European Group for Blood and Marrow Transplantation Severe Aplastic Anaemia Working Party

BACKGROUND

Immunosuppressive therapy has been used for successful treatment of severe aplastic anemia, but little information is available on outcome in older patients.

OBJECTIVE

To evaluate outcome in patients older than 50 years of age who received immunosuppressive therapy for aplastic anemia.

DESIGN

Retrospective cohort study.

SETTING

56 centers of the European Group for Blood and Marrow Transplantation (EBMT).

PATIENTS

810 patients with aplastic anemia reported between 1974 and 1997. Patients were evaluated according to age group: 60 years of age or older (n = 127), 50 to 59 years of age (n = 115), and 20 to 49 years of age (n = 568; reference group).

INTERVENTION

Antilymphocyte globulin, cyclosporine, or both.

MEASUREMENTS

Survival, cause of death, response to treatment, relapse rate, and risk for late complications were analyzed in all patients and by age group.

RESULTS

The 5-year survival rate was 57% (95% CI, 46% to 66%) in patients 50 to 59 years of age and 50% (CI, 39% to 60%) in patients 60 years of age or older compared with 72% (CI, 68% to 76%) in patients younger than 50 years of age (P < 0.001). Response to therapy, relapse rate, and risk for clonal complications were similar in all three age groups (P > 0.2). Age was significantly associated with an increased risk for death (relative risk compared with patients 20 to 49 years of age, 1.80 [CI, 1.29 to 2.52] for patients 50 to 59 years of age and 2.57 [CI, 1.87 to 3.53] for patients > or = 60 years of age), mainly because of bleeding or infection (P = 0.02). Response to immunosuppressive therapy in all patients at 12 months was 62% (CI, 58% to 66%); no difference was seen among the age groups in multivariate analysis (P > 0.2). Sixty-six of the 379 responding patients (17%) subsequently had relapse. The risk for clonal disorders at 10 years was 20% (CI, 15% to 27%).

CONCLUSIONS

Response to immunosuppression in aplastic anemia is independent of age, but treatment is associated with increased mortality in older patients.

High levels of thrombopoietin in sera of patients with essential thrombocythemia: cause or consequence of abnormal platelet production?

Thrombopoietin (TPO) is the most important regulator of megakaryocyte development and platelet production. Platelet production is thought to be regulated by a negative regulatory feed back loop. In an attempt to evaluate the role of TPO in the pathobiology of essential thrombocythemia (ET), we have examined levels of TPO and other cytokines with thrombopoietic activity (interleukin-6 and interleukin-11) in sera obtained from 25 patients with ET (ten treated, 15 untreated) and 117 healthy control subjects. TPO serum levels were assessed using a sandwich-antibody ELISA that utilizes a polyclonal rabbit antiserum for both capture and signal. The mean serum TPO level in 25 ET patients was significantly elevated (545+/-853 pg/ml) as compared with that in healthy controls (95.3+/-54.0 pg/ml,p<0.001). The difference in TPO serum levels between ten treated (781+/-1229 pg/ ml) and 15 untreated ET patients (388+/-458 pg/ml) did not reach statistical significance (p = 0.09). We conclude that either consumption or production of TPO is altered in ET. Failure of appropriate feedback regulation and continued megakaryocyte stimulation by an elevated TPO may play an important role in the pathobiology of ET.

Acute effects of recombinant human interleukin-6 on endocrine and central nervous sleep functions in healthy men

Interleukin-6 (IL-6) is a proinflammatory cytokine that has been shown to mediate, in addition to immune reactions, various endocrine and central nervous components of the acute phase response. In this context, the present study aimed to specify the contributions of IL-6 to the regulation of pituitary-adrenal secretory activity and GH and TSH secretion, as well as to the regulation of central nervous sleep and mood in healthy men. Effects of a low dose of IL-6 (0.5 microgram/kg body weight) were assessed, inducing plasma IL-6 concentrations closely comparable with those typically observed after infectious challenge. Each of the 16 male subjects participated in two 14-h sessions (between 1800 and 0800 h), receiving either placebo or human recombinant IL-6 sc at 1900 h. Blood was collected repeatedly to determine plasma hormone levels, serum concentrations of cytokines, and C-reactive protein. Moreover, mood was assessed, and sleep recordings were obtained between 2300 and 0700 h. The cytokine induced a prolonged increased in plasma concentrations of ACTH and cortisol (P < 0.001), but led to a decrease in TSH concentrations (P < 0.01). In response to IL-6, subjects reported fatigue and felt more inactive and less capable of concentrating than after placebo. Sleep architecture was altered significantly by the cytokine. Slow-wave sleep was decreased during the first half and increased during the second half of sleep. Rapid eye movement sleep during the entire nocturnal sleep time was significantly decreased. After IL-6, body temperature rose slightly. C-reactive protein concentrations were dramatically increased 12.5 h after substance administration (P < 0.001). IL-6 did not affect serum concentrations of IL-2, IL-8, interferon-alpha, and interferon-gamma. The results underscore the importance of IL-6 in the cascade of cytokines for the neuroendocrine response during the acute phase reaction. In addition, IL-6 appears to be involved in changes of sleep and behavior accompanying infection and inflammatory disorders.

Lack of efficacy of recombinant human interleukin-6 in patients with advanced renal cell cancer: results of a phase II study

The present phase II study was undertaken to assess antitumoral activity, safety and tolerability of recombinant human interleukin-6 (rh IL-6) in patients with advanced renal cell cancer. Rh IL-6 was administered as a daily subcutaneous injection at a fixed dose of 150 micrograms/day for a maximum of 42 consecutive days. 12 patients with metastatic renal cell cancer without previous immunotherapy were enrolled and were evaluated for response. No objective clinical responses were observed in the trial. Toxicity was moderate and reversible and mainly comprised fever, influenza-like symptoms, fatigue and moderate hepatotoxicity. Anaemia, leucocytosis, thrombocytosis and induction of an acute phase response were observed in most patients. In conclusion, prolonged subcutaneous administration of rh IL-6 on an outpatient basis is safe and feasible. However, rh IL-6 exhibited no antitumoral activity in patients with metastastic renal cell cancer. Profound regulatory effects on haematopoiesis and inflammatory response of rh IL-6 were observed.

Thrombopoietin serum levels in patients with aplastic anaemia: correlation with platelet count and persistent elevation in remission

In an attempt to evaluate the role of thrombopoietin (TPO) in the pathobiology of aplastic anaemia (AA), we have examined TPO levels in sera from 54 AA patients and 119 healthy controls. A total of 92 samples were collected from AA patients: 43 samples were harvested at diagnosis, 23 samples in the cytopenic period after treatment, and 26 samples when patients were in partial (n=10) or complete remission (n=16) following immunosuppressive treatment. TPO serum levels were assessed by a sandwich-antibody ELISA that utilized a polyclonal rabbit antiserum for both capture and signal. Serum samples from normal donors revealed a mean TPO level of 95.3 +/- 54.0 pg/ml (standard deviation). Mean TPO levels in AA sera collected at diagnosis and before onset of treatment were 2728 +/- 1074 pg/ml (P<0.001 compared to normal controls: mean platelet count at that time: 27x10(9)/l). TPO serum levels of AA patients in partial or complete remission after immunosuppressive treatment were significantly lower than TPO levels at diagnosis (P<0.001). However, despite normal platelet counts (mean 167x10(9)/l), TPO levels remained significantly elevated in complete remission (mean TPO 1009 +/- 590 pg/ml, P<0.001 compared to normal controls). There was a significant inverse correlation between serum TPO levels and platelet counts in AA patients who were not transfused for at least 2 weeks prior to sample collection (coefficient of correlation (r) = -0.70, P<0.0001). In summary, TPO levels were highly elevated in sera of patients with AA. Thus there is no evidence to suggest an impaired TPO response contributing to thrombocytopenia in AA. Thrombopoietin did not return to normal levels in remission, indicating a persisting haemopoietic defect in remission of AA. We hypothesize that elevated levels of TPO may be required to maintain normal or near normal platelet counts in remission of AA.

A possible role for thrombopoietin and its receptor c-mpl in the pathobiology of essential thrombocythemia

Essential thrombocythemia (ET) is a clonal myeloproliferative disorder of unknown origin primarily involving the megakaryocyte/platelet lineage. In an attempt to evaluate the role of the receptor c-mpl and its ligand thrombopoietin (TPO) in ET, various studies have been undertaken, the results of which are discussed herein. Normal or even elevated TPO levels in ET despite an increased megakaryocyte/platelet mass suggest abnormal feedback mechanisms in the regulation of TPO production and consumption. Deregulated levels of TPO in the circulation of patients with ET may be the result of an abnormal TPO consumption by platelets and megakaryocytes. It has been shown that proto-oncogene c-mpl is involved in spontaneous megakaryopoiesis in myeloproliferative disorders. Evidence for a decisive role of deregulated TPO in ET also comes from observations in mice overexpressing a TPO transgene where increased TPO production has resulted in a fatal myeloproliferative syndrome. Future research will study quantitative and qualitative deficiencies of c-mpl, the kinetics of the interaction of c-mpl with its ligand (TPO), and the role of autocrine or paracrine production of c-mpl ligand in increasing megakaryopoiesis so as to further elucidate its pathobiologic significance in ET.

Quantitative analysis of cobblestone area-forming cells in bone marrow of patients with aplastic anemia by limiting dilution assay

In the past, the analysis of primitive human hematopoietic progenitor cells with repopulating activity was limited by lack of appropriate in vitro assay systems. It was recently shown that cobblestone area-forming cells (CAFC) giving rise to cobblestone areas after 5 weeks in long-term marrow cultures (LTMC) represent a population of pluripotent progenitor cells with long-term marrow-repopulating activity. We have used a microtiter limiting dilution-type human LTMC system to quantitate the frequency of CAFC (week 5) in aplastic anemia (AA). In bone marrow mononuclear cells (BM-MNC) of healthy donors (n = 36) we observed a mean frequency of 84.4 CAFC per 10(5) BM-MNC (95% confidence interval limits, 66.4 to 102.4). The mean frequency of CAFC in BM of 31 AA patients was 6.6 per 10(5) BM-MNC (95% confidence interval limits, 5.3 to 7.9; n = 47). This frequency is significantly lower as compared with controls (P < .0001). The frequency of CAFC was reduced not only in pancytopenic AA patients (6.2 per 10(5) BM-MNC; P < .0001 v control), but also in patients in remission after immunosuppression (7.6; P < .0001 v control; P = .1 v pancytopenic AA patients). The CAFC frequency did not correlate with the severity or duration of the disease and did not predict response to immunosuppressive treatment. In summary, the frequency of primitive hematopoietic progenitor cells, as measured by the CAFC assay, is significantly reduced in AA. CAFC remain severely reduced even after hematologic recovery after immunosuppressive treatment. The low frequency of CAFC in remission patients is in keeping with other data pointing to a persisting defect of hematopoiesis in patients in remission after immunosuppressive treatment.

Long-term interleukin-3 and intensive immunosuppression in the treatment of aplastic anemia

We have assessed in a phase I/II clinical study the tolerability and efficacy of long-term application of recombinant human interleukin-3 (rh-IL-3) in combination with antithymocyte globulin (ATG) and cyclosporin A (CSA) in 13 patients with aplastic anemia who were refractory to or relapsed after previous immunosuppressive treatment. Four cohorts of three patients were consecutively enrolled so that they received rh-IL-3 on days 9, 6, 3 and 1 after start of ATG/CSA treatment. Yeast-derived recombinant human IL-3 was administered by daily subcutaneous injection until day 90 at a dosage of 250 micrograms/m2. Long-term application of rh-IL-3 was well tolerated. The combination of rh-IL-3 with immunosuppression did not modify the known toxicities of ATG and CSA. Incidence and severity of rh-IL-3-related adverse events was less than in other phase I/II trials of rh-IL-3 as single-agent therapy. One might speculate that co-medication with CSA alleviates rh-IL-3-induced side effects. Three of eight patients with refractory AA and all four patients with relapsed AA responded to the combined treatment within four months. The median time to response was 91.5 days. There was evidence for an rh-IL-3-dependent response in two patients. Long-term rh-IL-3 did not cause stem cell exhaustion. One patient died early during the course of the study from EBV-driven lymphoproliferative disease. Two patients developed acute myeloid leukemia 4 and 22 months after cessation of rh-IL-3. In conclusion, long-term rh-IL-3 in combination with immunosuppression is well tolerated. The response rate to the combined treatment in refractory and relapsed AA was high. Recombinant human IL-3-dependent responses suggest efficacy. A prospective randomized trial comparing immunosuppression alone versus a combination with rh-IL-3 is warranted.

Endocrine effects of recombinant interleukin 6 in man

In a phase II study, 5 male patients with a good performance status, who had metastatic renal cell carcinoma, received interleukin 6 (IL-6) to evaluate a possible antitumor effect of the cytokine. This offered the opportunity to investigate endocrine effects of IL-6 in man. The patients were studied the day before (day-1), and on days +1 and +21 of the IL-6 therapy (150 micrograms administered subcutaneously every day at 09.00 h). Blood was sampled at 09.00, 11.00, 13.00, 16.00, and 20.00 h. Compared with day -1, on days +1 and +21 serum levels of IL-6 were substantially elevated between 11.00 and 20.00 h. IL-6 significantly decreased serum thyrotropin (TSH) levels on day +1 (p < 0.05). The decrease was even more pronounced on day +21 when TSH concentrations were persistently below the respective values of day +1, suggesting, in addition to the acute action of IL-6, an effect developing with repeated IL-6 administrations. Total serum T3 and T4 levels were significantly lower on day +21 than on days -1 and +1. In contrast, free T3 and free T4 values did not differ among days -1, +1 and +21. Acutely, IL-6 had no effect on serum luteinizing hormone (LH) concentrations. However, on day +21, averaged serum LH levels (between 11.00 and 20.00 h) were significantly higher (8.4 +/- 1.1 IU/l) than on days -1 (6.5 +/- 0.2 IU/l) and +1 (6.4 +/- 0.4 IU/l). Average serum testosterone levels were slightly but not significantly enhanced on day +21. IL-6 did not influence follicle-stimulating hormone, growth hormone, or prolactin levels, neither acutely nor after 3 weeks of daily administration. The data indicate a modulating effect of IL-6 on secretory activity of different endocrine axes in man.

Clonal hematopoiesis as defined by polymorphic X-linked loci occurs infrequently in aplastic anemia

We evaluated the methylation status of the X-linked gene phosphoglycerate kinase (PGK1) and the DXS 255 locus detected by probe M27 beta to study clonality in acquired aplastic anemia (AA). A total of 30 females were suitable for clonal analysis of peripheral blood polymorphonuclear cells (PMN) and mononuclear cells using a polymerase chain reaction-based procedure in 24 patients and Southern blotting in 9. Overall, 10 of 30 patients exhibited an imbalanced X-inactivation pattern. However, in 4 patients, analysis of constitutional DNA suggested a skewed methylation pattern and 2 further cases had to be excluded because of the lack of an appropriate control. A truly clonal pattern was thus established in 4 of 30 (13%) patients. In 7 patients who later developed clonal disorders of hematopoiesis, X-inactivation analysis did not predict this event in any case. In patients with a paroxysmal nocturnal hemoglobinuria phenotype, there was no correlation between the proportion of phosphatidylinositol glycan anchored protein (PIG-AP)-deficient blood cells and the corresponding X-inactivation pattern. X-inactivation analysis detected clonal hematopoiesis in only 3 of 10 patients with a deficiency in PIG-AP in the cell population under study, but sorting of nucleated cells on the basis of PIG-AP expression showed the clonal nature of PIG-AP-deficient cells. We conclude that the majority of patients with AA show polyclonal hematopoiesis using X-linked clonal analysis, but that minor clonal populations, such as PIG-AP-deficient cells, may not be detected unless sorted cell populations are separately analyzed.

Emergence of CD52-, phosphatidylinositolglycan-anchor-deficient T lymphocytes after in vivo application of Campath-1H for refractory B-cell non-Hodgkin lymphoma

CD52 is a phosphatidylinositolglycan (PIG)-anchored glycoprotein (PIG-AP) expressed on normal T and B lymphocytes, monocytes, and the majority of B-cell non-Hodgkin lymphomas. We observed the emergence of CD52- T cells in 3 patients after intravenous treatment with the humanized anti-CD52 monoclonal antibody Campath-1H for refractory B-cell lymphoma and could identify the underlaying mechanism. In addition to the absence of CD52, the PIG-AP CD48 and CD59 were not detectable on the CD52- T cells in 2 patients. PIG-AP-deficient T-cell clones from both patients were established. Analysis of the mRNA of the PIG-A gene showed an abnormal size in the T-cell clones from 1 of these patients, suggesting that a mutation in the PIG-A gene was the cause of the expression defect of PIG-AP. An escape from an immune attack directed against PIG-AP+ hematopoiesis has been hypothesized as the cause of the occurrence of PIG-AP-deficient cells in paroxysmal nocturnal hemoglobinuria (PNH) and aplastic anemia. Our results support the hypothesis that an attack against the PIG-AP CD52 might lead to the expansion of a PIG-anchor-deficient cell population with the phenotypic and molecular characteristics of PNH cells.

[Paroxysmal nocturnal hemoglobinuria. Clinical experiences with 40 patients at one center over 25 years]

In one centre (the medical department of the University of Ulm), over a period of 25 years, the diagnosis of paroxysmal nocturnal haemoglobinuria (PNH) had been made in 40 patients (27 women, 13 men). The data on these patients were analysed and the findings compared with those reported in the literature. Criteria for inclusion were a positive sucrose haemolysis and acid-serum test. Leading clinical symptoms were anaemia, tendency towards bleeding and infections, haemolysis, abdominal pain and thromboembolism. The age at which main symptoms first appeared was most often in the third and fourth decade of life. The sex ratio of 2:1 (female to male) was unusual. PNH was frequently (in 22 patients) associated with aplastic anaemia. If bone marrow transplantation, at present the only curative procedure, was not possible and there was PNH alone, treatment was supportive and directed at relief of symptoms. The course of the disease was highly variable. Lack fo prognostic criteria made it difficult to define indications for intensive therapeutic measures. While haemolytic crisis and thromboembolism are frequent complications in isolated PNH haematopoetic insufficiency defines clinical outcome in PNH combined with aplastic anaemia.

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.

Evidence for a paracrine pathway of B-cell stimulation in hairy cell leukaemia

It is a well-known phenomenon that the growth of malignant B-lymphocytes, i.e. hairy cells, is regulated by cytokines. Several investigators have suggested that the stimulating cytokines are produced by the malignant B cells themselves, indicating an autocrine growth regulation. In this paper we demonstrate that T-lymphocyte clones produce soluble mediators which stimulate the growth of malignant B lymphocytes. The incidence of the growth-stimulating T-cell clones derived from peripheral blood is identical in patients with hairy cell leukaemia (HCL) and healthy controls. About 50% of the clones stimulate the growth of hairy cells, but not the growth of purified B lymphocytes of healthy donors. The stimulating activity of a single clone varies when tested on different hairy cells. Interferon alpha (IFN alpha), but not antibodies against tumour necrosis factor alpha (TNF alpha) or interleukin-2 (IL-2), completely inhibit the growth-stimulating activity. Our results indicate that a paracrine growth regulation has to be considered in addition to the postulated autocrine loop in the growth regulation of malignant B cells.

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)