Human herpesvirus 6 in biopsies from patients with gastrointestinal symptoms after allogeneic stem cell transplantation.

Gastrointestinal complications are frequent after allogeneic stem cell transplantation (allo-SCT). Main differential diagnoses are graft-versus-host disease (GvHD) and viral infections. In this retrospective analysis, we included 50 patients with severe vomiting or diarrhea in the first year after allo-SCT. One hundred two biopsies obtained by colonoscopy or endoscopy of the upper gastrointestinal tract were analysed by conventional histology for signs of GvHD and by qualitative polymerase chain reaction (PCR) for viral DNA of human herpesvirus 6 (HHV-6) and other virus of the herpes family. DNA of HHV-6 was detected in 38 of 75 initial samples (51%) and in 19 of 27 follow-up biopsies (70%). In the initial samples (n = 75), HHV-6 DNA was detected in 20/37 (54%) biopsies in the presence of GvHD compared to 18/38 (47%) biopsies without signs of GvHD. At the time of the first endoscopic investigation, most patients received antiviral prophylaxis with aciclovir. None of the follow-up biopsies was HHV-6 DNA negative after antiviral treatment with aciclovir, foscarnet or ganciclovir. By univariate analysis, no risk factor for HHV-6 detection could be demonstrated. In this cohort of patients with severe gastrointestinal complications, there was no significant difference in the overall survival between patients with or without HHV-6 DNA detection in the gastrointestinal tract. In summary, the detection of HHV-6 DNA had no impact on overall survival. Moreover, antiviral therapy against HHV-6 was without effect. Thus, positive PCR results in GI tract samples do not necessarily reflect reactivation of HHV-6. Further studies are needed to define the significance of HHV-6 for GI tract symptoms after allo-SCT.

[Treatment of adult acute lymphoblastic leukemia according to GMALL 07/2003 study protocol in the Czech Republic - the first experience]. / Lécba dospelých pacientu s akutní lymfoblastickou leukemií dle protokolu GMALL 07/2003 a její výsledky--první zkusenosti v Ceské republice.

INTRODUCTION: We present two years' experience in the treatment of adult acute lymphoblastic leukemia (ALL) according to the German GMALL 07/2003 study protocol at CELL (Czech leukemia study group--for life) hematological centers in the Czech Republic. METHODS: A total number of 37 patients were included in this analysis. We evaluated complete remission and molecular remission rate, incidence of relapse, patients' status at the end of the follow-up period, incidence of chemotherapy-related adverse events and causes of death. A statistical analysis of risk factors affecting survival was carried out. RESULTS: Complete remission was achieved in 36 (97%) patients and molecular remission in 16 (62%) of 26 evaluable patients. Disease relapse occurred in 5 (14%) patients. At the end of the follow-up period with a median of 261 days, 28 (76%) patients were alive in complete remission, one (3%) with relapsed disease and 8 (22%) dead. Treatment toxicity resulted in death in 5 cases, relapse or progression of ALL in 3 patients. Adverse events most often followed consolidation I, induction phase I, consolidation II and induction phase II. Infectious complications in the context of febrile neutropenia, GIT mucositis and side effects of PEG-asparaginase were the most common adverse events observed. The toxicity of allogeneic transplantation was not unexpected, four (25%) patients died after transplantation. Two-year progression-free and overall survival were 66% and 70%, respectively. High risk ALL, age over 35 years, CNS infiltration, disease relapse and permanent minimal residual disease were identified as the major adverse prognostic risk factors. Practical experiences and possible pitfalls of the protocol are described in the discussion. CONCLUSION: Our initial impression is promising. The treatment is feasible, the results very good and the toxicity acceptable. Patients at high risk should be headed to allogeneic transplantation, since the results ofconsolidation chemotherapy alone are very poor in this group. We believe that this study protocol could become a standard adult acute lymphoblastic leukemia treatment in the Czech Republic.

[Role of multicenter study groups for clinical research in hematology and oncology]. / Bedeutung von Multicenterstudiengruppen für die klinische Forschung in der Hämatologie und Onkologie.

During the past 25 years a highly effective infrastructure for clinical trials was developed in hematology. Following initial funding by the BMFT (Ministry for Research and Technology) a number of large multicenter study groups for leukemia and lymphoma were developed. Treatment results from these studies often represent the"gold standard". However, since no standard therapy is defined for these diseases, the study groups aim to treat all patients within treatment optimization trials (TOT) to combine research and care. They contribute considerably to quality control in therapy and diagnostics, e.g., by establishing central reference laboratories. The regulatory requirements for clinical trials were extended considerably after the activation of the 12th drug law and TOTs now have to fulfill requirements similar to registration trials in the pharmaceutical industry. Due to the considerable bureaucratic effort and increased costs, only few large multicenter trials could thereafter be initiated and a substantial disadvantage for independent academic research becomes clearly evident.

Defective in vitro growth of the hemopoietic progenitor cells in the acquired immunodeficiency syndrome.

In addition to immunologic derangement, hematological abnormalities have been reported in the majority of patients with acquired immunodeficiency syndrome (AIDS). In this study 15 patients with AIDS or AIDS-related complex (ARC) were evaluated for the in vitro growth of hemopoietic progenitor cells. In all patients a significant reduction of growth (mean +/- SEM) of colony-forming unit-granulocyte, erythrocyte, macrophage, (megakaryocyte) (CFU-GEM) (1.2 +/- 0.3), burst-forming unit-erythroid (BFU-E) (17 +/- 10), CFU-megakaryocyte (CFU-Mk) (1.7 +/- 0.6), and CFU-granulocyte-macrophage (CFU-GM) (35 +/- 10) was observed in comparison with normal controls. Depletion of T cells from the bone marrow before culture led to a significant increase in colony growth, which indicated an imbalance of the normally modulating T cell subsets. This increase was reversed by readdition of autologous T cells causing a decrease in colony growth to a degree, dependent on the T4 to T8 ratio. A decreased number of hemopoietic progenitor cells and/or a defective modulation of progenitor cell growth, normally carried out by T lymphocyte subsets, might be the cause of the hematological abnormalities in AIDS patients.

Glucoregulation during exercise: hypoglycemia is prevented by redundant glucoregulatory systems, sympathochromaffin activation, and changes in islet hormone secretion.

During mild or moderate nonexhausting exercise, glucose utilization increases sharply but is normally matched by increased glucose production such that hypoglycemia does not occur. To test the hypothesis that redundant glucoregulatory systems including sympathochromaffin activation and changes in pancreatic islet hormone secretion underlie this precise matching, eight young adults exercised at 55-60% of maximal oxygen consumption for 60 min on separate occasions under four conditions: (a) control study (saline infusion); (b) islet clamp study (insulin and glucagon held constant by somatostatin infusion with glucagon and insulin replacement at fixed rates before, during and after exercise with insulin doses determined individually and shown to produce normal and stable plasma glucose concentrations prior to each study); (c) adrenergic blockage study (infusions of the alpha- and beta-adrenergic antagonists phentolamine and propranolol); (d) adrenergic blockade plus islet clamp study. Glucose production matched increased glucose utilization during exercise in the control study and plasma glucose did not fall (92 +/- 1 mg/dl at base line, 90 +/- 2 mg/dl at the end of exercise). Plasma glucose also did not fall during exercise when changes in insulin and glucagon were prevented in the islet clamp study. In the adrenergic blockade study, plasma glucose declined initially during exercise because of a greater initial increase in glucose utilization, then plateaued with an end-exercise value of 74 +/- 3 mg/dl (P less than 0.01 vs. control). In contrast, in the adrenergic blockade plus islet clamp study, exercise was associated with glucose production substantially lower than control and plasma glucose fell progressively to 58 +/- 7 mg/dl (P less than 0.001); end-exercise plasma glucose concentrations ranged from 34 to 72 mg/dl. Thus, we conclude that: (a) redundant glucoregulatory systems are involved in the precise matching of increased glucose utilization and glucose production that normally prevents hypoglycemia during moderate exercise in humans. (b) Sympathochromaffin activation, perhaps sympathetic neural norepinephrine release, plays a primary glucoregulatory role by limiting glucose utilization as well as stimulating glucose production. (c) Changes in pancreatic islet hormone secretion (decrements in insulin, increments in glucagon, or both) are not normally critical but become critical when catecholamine action is deficient. (d) Glucoregulation fails, and hypoglycemia can develop, both when catecholamine action is deficient and when changes in islet hormones do not occur during exercise in humans.

Nonsecretory primary plasma cell leukemia with good response to thalidomide-based treatment.

Primary plasma cell leukemia (PCL) is a rare hematologic disorder with distinct features. The criterion for the diagnosis of PCL is based on the finding of malignant plasma cells in the peripheral blood (more than 2 x 10(9)/L or more than 20% of white blood cells). We report a case of a 74-year-old patient with primary nonsecretory PCL. Examination of blood smears led to the diagnosis of PCL, which was confirmed by bone marrow biopsy. Due to the patient's impaired general condition, intensive chemotherapy could not be administered. After an oral induction chemotherapy consisting of cyclophosphamide and high dose dexamethasone followed by one cycle of high-dose dexamethasone and thalidomide no evidence of the disease in the peripheral blood was detectable. Consequently, the patient was put on a thalidomide maintenance therapy. Six months after first diagnosis, the patient was found to have bone marrow and peripheral blood relapse with anemia and neutropenia in the clinical context of acute on chronic renal failure. After a limited response to further chemotherapy, the patient died 14 months after the first diagnosis while on dexamethasone maintenance. We conclude that monotherapy with thalidomide might be an alternative maintenance strategy with limited response duration for patients with primary PCL in impaired general condition.

Genomic imprinting of insulin-like growth factor 2 (IGF-2) in chronic synovitis.

OBJECTIVE: To search for relaxation or loss of IGF-2 imprinting (LOI) in rheumatoid arthritis (RA) synovial tissues. DESIGN: The genotype of IGF-2 was determined in 25 freshly isolated synovial tissue samples with signs of active inflammation by polymerase chain reaction (PCR) and restriction fragment length polymorphism. Imprinting was determined in synovial tissue mononuclear cells (STMC) of five informative heterozygous patients by reverse transcriptase (RT)-PCR. Mitogen-stimulated peripheral blood mononuclear cells (PBMC) from six informative healthy donors were selected for control. RESULTS: In vitro proliferation of CD4+ and CD8+ PB T cells, and also of CD19+ PB B cells was detectable upon mitogen stimulation. Furthermore, MHC II molecule expression on synovial B and T cells indicated in vivo cell activation. Monoallelic IGF-2 expression was seen in PBMC cultures from two healthy donors under both, resting and stimulating conditions. In two other PBMC cultures, LOI occurred exclusively after 24 h of stimulation. PBMC from two other healthy donors showed LOI under both, resting and stimulating conditions. Mitogen induced and spontaneous LOI was reversible in each one PBMC culture after 72 h. In contrast, none of the informative STMC cultures showed LOI. CONCLUSIONS: LOI in lymphocytes may occur spontaneously or inducible. However, longstanding activation of lymphocytes in RA synovitis appears not to be related to this mechanism.

PIC-1/SUMO-1-modified PML-retinoic acid receptor alpha mediates arsenic trioxide-induced apoptosis in acute promyelocytic leukemia.

Fusion proteins involving the retinoic acid receptor alpha (RARalpha) and PML or PLZF nuclear protein are the genetic markers of acute promyelocytic leukemia (APL). APLs with PML-RARalpha or PLZF-RARalpha fusion protein differ only in their response to retinoic acid (RA) treatment: the t(15;17) (PML-RARalpha-positive) APL blasts are sensitive to RA in vitro, and patients enter disease remission after RA treatment, while those with t(11;17) (PLZF-RARalpha-positive) APLs do not. Recently it has been shown that complete remission can be achieved upon treatment with arsenic trioxide (As2O3) in PML-RARalpha-positive APL, even when the patient has relapsed and the disease is RA resistant. This appears to be due to apoptosis induced by As2O3 in the APL blasts by poorly defined mechanisms. Here we report that (i) As2O3 induces apoptosis only in cells expressing the PML-RARalpha, not the PLZF-RARalpha, fusion protein; (ii) PML-RARalpha is partially modified by covalent linkage with a PIC-1/SUMO-1-like protein prior to As2O3 treatment, whereas PLZF-RARalpha is not; (iii) As2O3 treatment induces a change in the modification pattern of PML-RARalpha toward highly modified forms; (iv) redistribution of PML nuclear bodies (PML-NBs) upon As2O3 treatment is accompanied by recruitment of PIC-1/SUMO-1 into PML-NBs, probably due to hypermodification of both PML and PML-RARalpha; (v) As2O3-induced apoptosis is independent of the DNA binding activity located in the RARalpha portion of the PML-RARalpha fusion protein; and (vi) the apoptotic process is bcl-2 and caspase 3 independent and is blocked only partially by a global caspase inhibitor. Taken together, these data provide novel insights into the mechanisms involved in As2O3-induced apoptosis in APL and predict that treatment of t(11;17) (PLZF-RARalpha-positive) APLs with As2O3 will not be successful.

Monitoring minimal residual disease by quantification of genomic chromosomal breakpoint sequences in acute leukemias with MLL aberrations.

An estimated 10% of acute leukemias carry mixed-lineage leukemia (MLL) fusion genes. Approximately 50 different fusion partners of the MLL gene have already been molecularly identified. These leukemias are commonly regarded as high-risk cases and are treated accordingly with intensified therapy regimens, including hematopoietic stem cell transplantation. However, a subset of patients may achieve long-term remissions with conventional therapy. Monitoring minimal residual disease (MRD) is undoubtedly of great value in clinical decision making, also in the pre- and post-transplant setting. Here, we describe a novel method for detecting MRD in leukemias with MLL aberrations. The method is based on monitoring patient-specific chromosomal breakpoint DNA sequences. This has several advantages over other methods that are based either on detecting specific RNA molecules of MLL fusion genes or on surrogate markers. An accurate and absolute quantification of the MRD level is possible. No reference to housekeeping genes is necessary and the target structure is much more stable than any mRNA fusion transcript.

Long-term survival data from a phase 3 study of Filgrastim as an adjunct to chemotherapy in adults with de novo acute myeloid leukemia.

We previously reported the results of a double-blind, placebo-controlled study of Filgrastim in patients with de novo AML undergoing induction and consolidation chemotherapy. The study demonstrated that Filgrastim was effective and well tolerated and had no impact on complete remission or survival. We now report follow-up data on these patients, assessing long-term effects with emphasis on prognostic indicators. After a median follow-up of 7 years, 434 (83%) patients were dead, 73 (14%) were alive, and 14 (3%) were lost to follow-up. The proportions of deaths were similar in the Filgrastim (83%) and placebo (84%) groups. No differences in median time to death (1.04 years Filgrastim, 1.13 years placebo; P = 0.97) or median disease-free survival (0.86 years Filgrastim, 0.79 years placebo; P = 0.52) were evident. Proportional hazard modeling identified age, performance status, and French-American-British subtype as independent predictors for survival (P < 0.001, P = 0.005, and P = 0.036, respectively), whereas cytogenetic status was not (P = 0.118). Filgrastim had no effect on overall survival in any of these subgroup analyses as none of the treatment comparisons were statistically significant. These findings indicate that Filgrastim can be effectively used to support patients with AML undergoing induction and consolidation chemotherapy without worsening long-term disease outcome.

Comparative analysis of hypermethylation of cell cycle control and DNA-mismatch repair genes in low-density and CD34+ bone marrow cells from patients with myelodysplastic syndrome.

Hypermethylation of CpG islands within the promoter region is one of the mechanisms by which genes are inactivated and may be one of the reason for silencing of cell cycle control or DNA-mismatch repair genes in myelodysplastic syndrome (MDS). Since the function of cell cycle control genes including the cyclin-dependent kinase inhibitors known as p15(INK4b) and p16(INK4a), as well as p14(ARF) which blocks MDM-2 (an inhibitor of p53), the retinoblastoma (RB1) protein and the mismatch repair gene MGMT is critical for hematopoietic proliferation and differentiation, we performed methylation specific polymerase chain reaction (MSP) in low-density, non-adherent bone marrow cells from 49 patients with MDS. In addition, expression of p15(INK4b) and RB1 was analysed by quantitative real-time PCR. From selected patients, we analyzed the methylation pattern of cell cycle control genes in CD34+ bone marrow cells. Thirty-nine of 49 cases (80%) had at least one of five genes methylated in our MDS samples by analysing low-density non-adherent bone marrow cells. The frequency of p15(INK4b) methylation was 34 of 49 samples (69%). The incidence of methylation of both p14(ARF) and p16(INK4a) was four of 49 (8%). RB1 gene was methylated in seven samples (14%) and each patient had RA. Interestingly, none of these genes were methylated in the purified CD34+ hematopoietic stem cells from the MDS patients. Furthermore, all our RARS patients had a methylated p15(INK4b) promoter correlating with non-detectable expression of this gene in bone marrow cells from those patients. These results indicate that hypermethylation of cell cycle control genes in MDS may occur late during the differentiation of myelodysplastic stem cells.

Molecular heterogeneity of sporadic adult Burkitt-type leukemia/lymphoma as revealed by PCR and cytogenetics: correlation with morphology, immunology and clinical features.

Chromosomal translocations involving the MYC oncogene are a hallmark of Burkitt lymphoma but they are only found in a varying frequency in mature Burkitt-type acute lymphoblastic leukemia (B-ALL). We have investigated samples of 56 sporadic Burkitt leukemia/lymphoma patients for the translocations t(8;14)(q24;q32), t(2;8)(p11;q24) and t(8;22)(q24;q11). Long PCR was used for detecting the immunoglobulin heavy chain (IgH) translocation and cytogenetics and/or fluorescence in situ hybridization for detecting the 'variant' MYC translocations. A total of 29 samples (51.8%) were t(8;14)-positive by long PCR. Approximately one-third had a chromosomal breakpoint in the IgH joining region while the others had breakpoints in the IgH switch regions. Among them were two cases with a previously unreported MYC translocation into the IgE switch region. Long PCR was more reliable compared to conventional cytogenetics for detecting the t(8;14). Epstein-Barr virus was detected in high copy number in two (3.6%) t(8;14)-positive cases by real-time quantitative PCR. Human herpesvirus 8 was not detected in any case by nested PCR. A typical L3 or L3-compatible cytomorphology was highly predictive (>80%) but not specific of a MYC translocation. A total of 34 patients were treated according to the GMALL B-ALL therapy protocols and there was no significant difference in overall survival between patients with or without t(8;14).

BCR-ABL mediates arsenic trioxide-induced apoptosis independently of its aberrant kinase activity.

In the prechemotherapy era arsenic derivatives were used for treatment of chronic myelogenous leukemia, a myeloproliferative disorder characterized by the t(9;22) translocation, the Philadelphia chromosome (Ph+). In acute promyelocytic leukemia response to arsenic trioxide (As2O3) has been shown to be genetically determined by the acute promyelocytic leukemia-specific t(15;17) translocation product PML/RARalpha. Hence, we reasoned that As2O3 might have a selective inhibitory effect on proliferation of BCR-ABL-expressing cells. Here, we report that: (a) As2O3 induced apoptosis in Ph+ but not in Ph- lymphoblasts; (b) enforced expression of BCR-ABL in U937 cells dramatically increased the sensitivity to As2O3; (c) the effect of As2O3 was independent of BCR-ABL kinase activity; and (d) As2O3 reduced proliferation of chronic myelogenous leukemia blasts but not of peripheral CD34+ progenitors. In summary, these data establish As2O3 as a tumor cell-specific agent, making its clinical application in Ph+ leukemia feasible.

Blinatumomab vs historical standard therapy of adult relapsed/refractory acute lymphoblastic leukemia.

We compared outcomes from a single-arm study of blinatumomab in adult patients with B-precursor Ph-negative relapsed/refractory acute lymphoblastic leukemia (R/R ALL) with a historical data set from Europe and the United States. Estimates of complete remission (CR) and overall survival (OS) were weighted by the frequency distribution of prognostic factors in the blinatumomab trial. Outcomes were also compared between the trial and historical data using propensity score methods. The historical cohort included 694 patients with CR data and 1112 patients with OS data compared with 189 patients with CR and survival data in the blinatumomab trial. The weighted analysis revealed a CR rate of 24% (95% CI: 20-27%) and a median OS of 3.3 months (95% CI: 2.8-3.6) in the historical cohort compared with a CR/CRh rate of 43% (95% CI: 36-50%) and a median OS of 6.1 months (95% CI: 4.2-7.5) in the blinatumomab trial. Propensity score analysis estimated increased odds of CR/CRh (OR=2.68, 95% CI: 1.67-4.31) and improved OS (HR=0.536, 95% CI: 0.394-0.730) with blinatumomab. The analysis demonstrates the application of different study designs and statistical methods to compare novel therapies for R/R ALL with historical data.

Reduced methyl group acceptance of 1-beta-D-arabinofuranosylcytosine-containing DNA polymers.

Previous studies have shown that 1-beta-D-arabinofuranosylcytosine (ara-C) can induce differentiation of various malignant cells and that DNA methylation patterns become altered under ara-C treatment of those cells. The aim of this study was to investigate whether this influence on DNA methylation is caused by a direct effect of DNA-incorporated ara-C molecules on nuclear DNA methylase. For this reason, we constructed various ara-C-substituted DNA polymers and used them as substrates for highly purified eukaryotic DNA methylase isolated from murine P815 mastocytoma cells. The ara-C incorporation into DNA polymers was measured by either an ara-C-specific radioimmunoassay or by use of radioactive-labelled ara-C during the synthesis of those polymers. We found an inverse correlation between the level of ara-C substitution of the DNA polymers and their methyl group acceptance. Kinetic experiments performed with ara-C-modified DNA polymers pointed out that the mode of action of DNA methylase remains unaltered. DNA methylase is neither detached nor fixed at an ara-C site, but is somehow hindered in its enzymatic activity, probably by slowing down the walking mechanism. Hence, the previously observed hypermethylation of DNA of some eukaryotic cells, propagated in the presence of ara-C, is apparently not due to a direct effect of DNA-incorporated ara-C molecules on endogenous DNA methylase.

Chromosomal organization and localization of the human histone deacetylase 5 gene (HDAC5).

Histone deacetylases (HDACs) are important participants in the remodeling of chromatin structure and in the regulation of eukaryotic proliferation and differentiation. We have isolated and characterized the human HDAC5 genomic sequence, which spans a region of 39,138 bp and which has one single chromosomal locus. Determination of the exon-intron splice junctions established that HDAC5 is encoded by 26 exons ranging in size from 22 bp (exon 1) to 285 bp (exon 12). Characterization of the 5' flanking genomic region revealed that the human HDAC5 promoter lacks both the canonical TATA and CCAAT boxes. The human HDAC5 mRNA encodes a 1122 aa protein with a predictive molecular mass of 121.9 kDa and an isoelectric point of 5.84. Fluorescence in situ hybridization analysis localized the human HDAC5 gene to chromosome 17q21, a region which is characterized by frequent gains and losses of chromosomal material in several types of cancer.

Reproductive and endocrine gonadal functions in adults following multidrug chemotherapy for acute lymphoblastic or undifferentiated leukemia.

The impact of aggressive chemotherapy on reproductive and endocrine gonadal function was studied in ten women and ten men with acute lymphoblastic leukemia (ALL) or acute undifferentiated leukemia (AUL) in complete remission. Hormone determinations, sperm analyses, measurements of basal body temperature, and interviews with a standardized questionnaire were used for diagnostic evaluation. Elevated serum follicle-stimulating hormone (FSH) levels and azoospermia were seen in all male patients after completion of induction and consolidation therapy as a result of germ cell and stem cell loss. Recovery of spermatogenesis, as indicated by normalization of serum FSH values and sperm density, occurred in the second year of maintenance therapy in all men. Serum testosterone and luteinizing hormone (LH) values remained within normal limits indicating resistance of Leydig cells to chemotherapy. All female patients showed normal serum levels of gonadal steroids and gonadotropins, as well as an adequate increase in basal body temperature after intensified chemotherapy, indicating intact follicle function and ovulation. Most patients reported normal sexual functions after induction and consolidation therapy. These results demonstrate that multidrug chemotherapy induced significant impairment of reproductive function in all male patients with early and complete recovery. In contrast, endocrine gonadal function was unaffected in men treated with ALL/AUL. In female patients, neither reproductive nor endocrine functions were influenced by aggressive chemotherapy.

Biologic effects of recombinant human interleukin-3 in vivo.

The biologic in vivo effects of recombinant human interleukin-3 (rhIL-3) were assessed in a phase I clinical study of 30 patients with advanced malignancy. On day 1 rhIL-3 was administered by a single intravenous (IV) bolus injection, followed by subcutaneous (SC) injections once daily from day 2 to 15; at least three patients were treated at each dose level (60, 125, 250, and 500 micrograms/m2). A transient decrease of eosinophil and monocyte counts was observed immediately after IV injection of rhIL-3, whereas the neutrophil count remained unaffected. Total WBC counts and neutrophil counts increased dose dependently up to threefold, whereas a 10-fold to 50-fold rise was observed in levels of circulating eosinophils and basophils. Platelet counts increased up to twofold. Patients developed moderate increases of serum levels of soluble interleukin-2 receptors, beta 2-microglobin, and immunoglobulin M (IgM), and of the acute phase reactants, C-reactive protein (CRP), fibrinogen, and haptoglobin. An increase in interleukin-6 (IL-6) serum levels was detected in patients treated by IV bolus rhIL-3. The serum half-life of IV injected rhIL-3 was 20 +/- 3 minutes; after SC administration, 210 +/- 15 minutes. Administration of rhIL-3 was generally well tolerated, with mild fever, headache, and local reactions at the injection site being the most frequent side effects. The primary course of the underlying malignant diseases was not significantly altered by administration of rhIL-3. The results indicate that rhIL-3 acts in vivo as a multilineage hematopoietic growth factor and a weak inflammatory mediator that may be used successfully to improve states of hematopoietic failure.