POS0197 SARS-CoV-2 INFECTION CAUSED THROMBOSIS IN THE LUPUS MODEL WITH ANTIPHOSPHOLIPID ANTIBODY, WHEREAS COVID-19 ASSOCIATED THROMBOSIS WAS IRRELEVANT IN PATIENTS WITH POSITIVE ANTIPHOSPHOLIPID ANTIBODY

Background

Thrombosis is a unique complication in coronavirus disease 2019 (COVID-19). We have reported that elevated ferritin and D-dimer on admission were the risk factors of thromboses by analyzing the patients sequentially admitted to our hospital due to COVID-19 (1). However, we have not analyzed thrombotic complications in the view of the antiphospholipid antibodies (aPLs), which are frequently detected in the COVID-19 patients.

Objectives

To elucidate the thrombogenic effects of aPLs in COVID-19, we analyzed the development of thrombosis in three lupus models after SARS-CoV-2 infection. Additionally, we evaluated the association of thrombotic events and the serum profile of aPLs in Japanese patients with COVID-19.

Methods

Three animal models of lupus (MRL-lpr/lpr, NZBxNZW F1 and NZW×BXSB F1) were evaluated in this study. NZW×BXSB F1 was also considered as a model of antiphospholipid syndrome (APS) since aPLs were detected with a high titer (2). Experimental SARS-CoV-2 infection was induced using mouse-passaged virus strain (3). The incidence of thromboses in the lungs and kidneys were identified by evaluating H&E staining and PTAH staining of paraffin-embedded sections. We have experienced 44 thrombotic events in 34 out of 594 patients admitted to our institute. As a non-thrombotic COVID-19, 68 patients were selected to make a 1 to 2 matched-pair based on the propensity score. In total 102 patients, seven types of aPLs (anti-cardiolipin (CL) IgG/IgM, anti-β2GP1 IgG/IgA/IgM, and anti-phosphatidyl serine/prothrombin complex (PS/PT) IgG/IgM) were measured using specific ELISA kits. The patients’ clinical characteristics and serological profile of aPLs were further evaluated.

Results

We identified the development of thromboses in the lungs or kidneys in 6 out of 12 (50%) NZW×BXSB F1 mice after the SARS-CoV-2 infection, whereas no thrombosis was observed in non-infected mice. Further, there was no thrombosis in the other lupus models (0%) after the infection. These findings might suggest the pathogenic role of aPLs under the SARS-CoV-2 infection.

Among our COVID-19 patients, 39 out of 102 (38%) were tested positive for one or more aPLs. The positive ratios of any aPLs were statistically indifferent between the patients with or without thrombosis; anti-CL IgG (8.8% vs 5.9%)/IgM (0% vs 5.9%), anti-β2GP1 IgG (21% vs 12%)/IgA (8.8% vs 15%)/IgM (0% vs 1.5%), and anti-PS/PT IgG (0% vs 2.9%)/IgM (12% vs 13%), respectively. In addition, their titers were relatively lower than those observed in APS patients. The patients’ characteristics and the prognosis of COVID-19 were comparable regardless of the detection of any aPLs. These findings suggested that COVID-19 associated aPLs were irrelevant to thrombotic complications.

Conclusion

Thromboses were induced after the infection of SARS-CoV-2 only in the APS model. However, aPLs detected in COVID-19 patients have little impact on the development of thrombosis. SARS-CoV-2 infection might have a high risk of thrombosis, especially in APS patients, as shown in the case report (4). The discrepancy of its thrombogenic effects of aPLs might be explained by the low titer of the antibody or the diversity of antibody epitope. Further analyses are required to clarify the mechanisms of aPLs production and the development of thrombosis in COVID-19.

References

[1]Oba S, et al. Arterial and Venous Thrombosis Complicated in COVID-19: A Retrospective Single-Center Analysis in Japan. Front Cardiovasc Med. 2021 Nov 19;8:767074.

[2]Hashimoto Y, et al. Anticardiolipin antibodies in NZW x BXSB F1 mice. A model of antiphospholipid syndrome. J Immunol. 1992 Aug 1;149(3):1063-8.

[3]Iwata-Yoshikawa N, et al. A lethal mouse model for evaluating vaccine-associated enhanced respiratory disease during SARS-CoV-2 infection. Sci Adv. 2022 Jan 7;8(1):eabh3827.

[4]Chidharla A, et al. A Case Report of COVID-Associated Catastrophic Antiphospholipid Syndrome Successfully Treated with Eculizumab. J Blood Med. 2021 Oct 30;12:929-933.

Disclosure of Interests

Seiya Oba: None declared, Tadashi Hosoya Speakers bureau: Janssen Pharmaceutical K.K.

Daiichi Sankyo Company, limited

Asahi Kasei Corporation

Ono pharmaceuticals

Eisai

Eli Lilly, Daisuke Kawata: None declared, Wenshi Lee: None declared, Mari Kamiya: None declared, Yoji Komiya: None declared, Hideyuki Iwai: None declared, Yuko Nukui: None declared, Shuji Tohda: None declared, Shinsuke Yasuda Speakers bureau: Abbvie,

Asahi Kasei Pharma,

Chugai Pharmaceutical,

Eisai, Eli Lilly,

GlaxoSmithKline,

Mitsubishi Tanabe Pharma,

Ono pharmaceutical,

Pfizer., Consultant of: ImmunoForge, Grant/research support from: Abbvie,

Asahi Kasei Pharma,

Chugai Pharmaceutical,

CSL Behring,

Eisai,

ImmunoForge,

Mitsubishi Tanabe Pharma,

Ono pharmaceutical

Human herpesvirus 8 DNA in HIV-negative Japanese patients with multicentric Castleman's disease and related diseases

Multicentric Castleman's disease (MCD) is a lymphoproliferative disorder characterized by systemic lymphadenopathy and hypergammaglobulinemia. Recently, a French group reported that human herpesvirus 8 (HHV8) DNA was detected in tissue samples of MCD patients. The detection rate was especially high in human immunodeficiency virus (HIV)-positive MCD patients. Thus, HHV8 infection seems to be closely related to HIV infection. In Japan, the HIV infection rate in the general population is very low. To examine whether HHV8 is actually related to MCD in Japan, we performed nested polymerase chain reaction for the HHV8 genome using DNA samples from 7 patients with MCD and 23 patients with related diseases such as POEMS syndrome, amyloidosis, myeloma and lymphoma. They were all HIV-negative Japanese. Three of 7 MCD patients were positive for HHV8. There were no clear differences in clinical characteristics between HHV8-positive patients and negative ones. All other patients were negative for HHV8. Thus, we have shown that some MCD patients in Japan are also infected with HHV8.

Expression of Notch1 and Jagged1 proteins in acute myeloid leukemia cells

Cell fate of hematopoietic progenitors is regulated by interaction between Notch proteins on progenitors and Notch ligands such as Jagged1 on stromal cells. Since acute myeloid leukemia (AML) originates from dysregulated hematopoietic progenitors, some abnormalities in the Notch-Jagged system may exist in AML cells. As the first step to clarify this, we examined the expression of Notch1 and Jagged1 proteins in eight AML cell lines and 15 fresh AML samples by immunoblotting. In the Notch1 protein, two bands, a 300 kDa band and a 120 kDa band, which appeared to be a full-length protein and a transmembrane fragment, respectively, were recognized in five AML cell lines and six fresh samples. In addition, three of the five cell lines showed a 110 kDa fragment, which appeared to be from an intracellular domain, namely an active form. One cell line showed aberrant sized fragments, which suggested a structural abnormality. Jagged1 protein was recognized in six cell lines and six fresh samples. In four cell lines and four fresh samples, both Notch1 and Jagged1 proteins were observed. In these cells, Notch1 and Jagged1 proteins may interact among themselves. We showed that Notch1 and Jagged1 proteins are widely expressed in AML cells. We hypothesize that some abnormalities in the Notch-Jagged system which cause the excessive self-renewal and the block of differentiation, may be involved in the abnormal proliferation of AML cells.

[Molecular diagnostic tests in hematologic diseases]

Molecular diagnostic tests are widely performed in managing hematologic malignancies such as leukemia and lymphoma. In this article, we review the present application and problems of the tests. Karyotyping is performed at diagnosis of all kinds of hematologic malignancies. This method needs dividing cells as samples and skilled experts. Fluorescence in situ hybridization(FISH) analysis using cells in interphase is performed, for example, to monitor the effect of interferon on chronic myelogenous leukemia patients. The weak point of this method is that approximately 2% of false-positive cells are inevitable. Southern blot method is used for clonal analysis in some disease, for example, adult T-cell leukemia/lymphoma. Polymerase chain reaction(PCR) method using genomic DNA is performed for limited types of diseases such as lymphoma with bcl-2/IgH fusion gene. Reverse transcription(RT)-PCR method can detect fusion gene transcripts with high sensitivity. This method is useful for detecting minimal residual diseases after chemotherapy or bone marrow transplantation. To perform quantitative analysis, real-time PCR or competitive PCR must be done. In the near future, new technology such as gene expression profiling analysis using DNA microarrays or spectral karyotyping(SKY) method will be used in clinical practice.

A case of atypical chronic myeloid leukemia regarded as MDS with myeloproliferative features

We report a case of atypical chronic myeloid leukemia (aCML) who showed marked neutrophilia without dysplastic features, basophilia or monocytosis. These findings diverged somewhat from the FAB criteria for aCML. The patient's erythroid cells and megakaryocytes were dysplastic. His marrow cells formed no spontaneous colonies, as shown by cell culture. The cells formed many small-sized neutrophil colonies with G-CSF stimulation. Interestingly, they formed mainly neutrophil colonies with GM-CSF stimulation. These findings were different from those of chronic myelomonocytic leukemia cells and chronic granulocytic leukemia cells. This aCML case showed the cytological features of myelodysplastic syndrome.

Polymerase chain reaction detection of rearranged immunoglobulin heavy chain DNA in plasma samples is useful in the diagnosis of B-cell lymphoma

Using DNA extracted from plasma samples of B-cell non-Hodgkin's lymphoma (B-NHL) patients, we attempted to detect the monoclonal rearrangement of immunoglobulin heavy chain gene by amplifying complementarity-determining region 3 (CDR3) by semi-nested polymerase chain reaction (PCR) method (plasma PCR). In 19 of 37 (51%) cases, clonal DNA was detected. With the same PCR method using DNA extracted from peripheral blood mononuclear cells, clonal DNA was detected in 8 of the 37 cases (22%). These 8 were in advanced stages with bone marrow (BM) invasion mostly. On the other hand, the 19 positive cases by plasma PCR included those in early stages without BM invasion or with normal soluble interleukin-2 receptor (sIL-2R) and lactate dehydrogenase (LDH) values. In 15 healthy volunteers, plasma PCR showed no clonal DNA. In cases in which tumor biopsy was difficult to perform, plasma PCR was helpful for determining whether or not the tumor was B-NHL. Plasma PCR is simple and has high specificity, although its sensitivity is insufficient.

[DNA diagnosis of hematopoietic malignancies]

The recent advances in molecular biology and gene engineering have contributed considerably to the diagnosis and treatment of hematopoietic malignancies, such as leukemia and malignant lymphoma. These advances also made possible precise determination of the clonal origin of malignant cells, the subtype of leukemia or lymphoma, and the clinical prognosis in each patient. Furthermore, minimal residual malignant cells in leukemia or lymphoma patients after achieving complete remission could be detected by DNA analysis. Based on these analyses, treatment can theoretically be tailored for each patient. We discuss in the present paper the usefulness of DNA or gene analyses of immunoglobulin heavy chain gene in clonal assessment of lymphocytic malignancies and in detecting minimal residual disease in the patient.

Establishment of a double Philadelphia chromosome-positive acute lymphoblastic leukemia-derived cell line, TMD5: effects of cytokines and differentiation inducers on growth of the cells

A double Philadelphia chromosome (Ph)-positive leukemia cell line with common-B cell phenotype, designated TMD5, was established from the blast cells of a patient with double Ph-positive acute lymphoblastic leukemia. TMD5 cells expressed 190 kDa BCR/ABL chimeric protein and 145 kDa ABL protein. The cells proliferated without added growth factors. Autocrine growth mechanism was not recognized. The addition of growth factors such as G-CSF, GM-CSF, IL-3, IL-6, or Stem Cell Factor did not affect the growth. Herbimycin A suppressed the growth of TMD5 cells at the low concentration that did not affect Ph-negative cells. It suppressed tyrosine phosphorylation of intracellular proteins in TMD5 cells. Dexamethasone and dibutyryl cyclic AMP also suppressed the growth. They, however, did not affect the phosphorylation significantly. Neither all-trans retinoic acid nor interferon-alpha affected the growth. TMD5 cells, characterized minutely here and rare in that they have double Ph chromosomes, will be a useful tool for the study of Ph-positive leukemia.

Molecular typing of methicillin-resistant Staphylococcus aureus by polymerase chain reaction: distribution of the typed strains in hospitals

Three methods for molecular typing of methicillin-resistant Staphylococcus aureus using polymerase chain reaction (PCR) were compared. The method which amplified the variable number of tandem repeat of dru sequences grouped the isolates into six types. Whereas, the method examining restriction fragment length polymorphism of coagulase gene and the method using arbitrarily primed-PCR showed poor diversity in typing. We investigated the distribution of dru types in two hospitals. Obvious concentration of a type in one ward was not recognized in our hospital. In the other hospital, a rare type was detected from the inpatients in the pediatrics ward. It suggested that the infection was an epidemic. We also found that some patients were infected with more than two strains. Even if two isolates show the same type, it does not necessarily mean that they originated from one clone. However, this method brings meaningful information on nosocomial infection, more easily than other genotyping.

Phosphorylation of signaling proteins in factor-independent myeloid leukemia cell lines

We investigated the mechanisms of factor-independent growth of four human myeloid leukemia cell lines. The autocrine mechanisms were ruled out by RT-PCR method examining growth factor mRNA. The immunoblotting method showed that many proteins were tyrosine phosphorylated irrespective of the stimulation with growth factors (G-CSF and GM-CSF) in factor-independent cell lines while the phosphorylation was induced stimulation dependently in a factor-dependent cell line. MAP kinase was constitutively phosphorylated in factor-independent cell lines. JAK2 protein was not tyrosine phosphorylated before the stimulation. It was significantly phosphorylated after the stimulation in three factor-independent cell lines although the stimulation did not affect their growth. JAK1 protein was not phosphorylated either before or after the stimulation. In conclusion, constitutive phosphorylation of signaling proteins seemed to be related to factor-independent growth. MAP kinase was involved in the phosphorylation, while JAK1 and JAK2 were not.

Effect of vesnarinone, a quinolinone derivative, on the growth of leukemic blasts in acute myelogenous leukemia

We studied the effects of vesnarinone, a quinolinone derivative used clinically for the treatment of chronic congestive heart failure, on the leukemic blast progenitors in acute myelogenous leukemia (AML) patients and on the normal hematopoietic precursors, colony-forming unit in culture (CFU-C), and colony-forming unit erythroid (CFU-E). Leukemic blast progenitors made blast colonies in the presence of granulocyte-colony stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF), or interleukin-3 (IL-3). Blast colony-formation was suppressed by vesnarinone in a dose-responsive manner regardless of growth factor added. Vesnarinone suppressed the primary (PE1) and secondary (PE2) colony-formation of leukemic blast progenitors in six AML patients tested. The suppression by vesnarinone did not significantly differ between PE1 and PE2. This finding suggests that vesnarinone exerts an almost equivalent effects on the terminal divisions and the self-renewal of leukemic blast progenitors. Furthermore, this drug suppressed the growth of clonogenic cells of five AML cell lines, OCI/AML1a, OCI/AML2, OCI/AML3, OCI/AML5, and OCI/AML6. Normal hematopoietic precursors CFU-C and CFU-E were also suppressed by vesnarinone, although vesnarinone was less toxic to normal hematopoietic than to leukemic blast progenitors. The possible usefulness of vesnarinone as a new approach to the treatment of AML patients is discussed.

[Plasma cell leukemia with amyloid deposition and osteogenetic change at the site of an extramedullary plasmacytoma]

A 49-year-old man was admitted with swelling in the left lower extremity, and a mass in the left lower abdomen. Laboratory findings showed an increased WBC of 15,000/microliter with 41% plasma cells, and immunoglobulin (Ig) A of 2,557mg/dl with a monoclonal component. A roentgenogram and computed tomograph of the abdomen revealed that a 5 x 10 cm mass with calcification located in the iliopsoas muscle. Plasma cell leukemia with extramedullary plasmacytoma was diagnosed, and the patient was treated with high-dose dexamethasone (40 mg/day for 4 days), resulting in a good response with the disappearance of plasma cells in peripheral blood and a marked decrease in serum Ig A. However, the patient's condition deteriorated in spite of various treatments, and he died of heart failure 5 months after admission. With informed consent from relatives, a necropsy was performed and infiltration of plasma cells in the mass in the iliopsoas muscle was noted. We reported this case because plasma cell leukemia with amyloid deposition and osteogenesis at the site of extramedullary plasmacytoma is very rare.

Clonal involvement of eosinophils in therapy-related myelodysplastic syndrome with eosinophilia, translocation t(1;7) and lung cancer

We report a therapy-related MDS (RAEB) patient with eosinophilia, unbalanced translocation der(7)t(1;7) (q12;q22) and lung cancer. We observed no increase in cytokine levels in serum or in the conditioned medium (CM) of peripheral T cells cultured with or without IL-2. When bone marrow (BM) cells were cultured with GM-CSF, IL-3 and SCF in a semisolid system, the colonies were exclusively eosinophilic. Cytogenetic analysis of the colony cells identified the same chromosome abnormality in all metaphases to that of BM cells. Suspension and clonogenic colony assay of BM cells cultured with various cytokines showed predominant eosinophilic growth and differentiation with GM-CSF, but not with the other cytokines examined. These findings, together with mild morphological abnormalities of eosinophils, indicate clonal involvement of eosinophils in the myelodysplastic syndrome (MDS) clone, and that the eosinophilia was derived from the neoplastic clone with the translocation and was not associated with the patient's lung cancer.

Relation of protein kinase A and protein kinase C to signaling pathways of hematopoietic factors in leukemia cell lines

In terms of growth, differentiation, and signaling pathways of hematopoietic factors, the effects of protein kinase C (PKC) activator, 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and protein kinase A(PKA) activator, dibutyryl cyclic adenosine monophosphate (dbcAMP) were examined in vitro using three factor-responsive myeloid leukemia cell lines. TPA suppressed the growth of OCI/AML-1 and OCI/AML-5 cells but stimulated the proliferation of OCI/AML-4 cells. TPA differentiated OCI/AML-4 and OCI/AML-5 cells to macrophage-like cells. dbcAMP suppressed the growth of the three without differentiation. The stimulation of TPA induced tyrosine phosphorylation of some proteins in OCI/AML-4 and OCI/AML-5 cells. Their molecular weights were the same as those phosphorylated by hematopoietic factors. The patterns of phosphorylated proteins were different between the two. TPA induced the phosphorylation of MAP kinase, but not that of JAK2 protein in three cell lines. The stimulation of dbcAMP did not induce tyrosine phosphorylation in three cell lines. Overnight exposure of TPA inhibited the tyrosine phosphorylation induced by hematopoietic factors, although that of dbcAMP did not. We suggest a close relation of PKC to signaling pathways of hematopoietic factors, however, the ways of relation were diverse among the cell lines and the clear mechanism explaining its effects on growth and differentiation was not elucidated.

[Three cases of drug-induced hemolytic uremic syndrome]

We report three cases of drug-induced hemolytic uremic syndrome (HUS). Three patients with advanced gastrointestinal cancer underwent a curative operation and adjuvant chemotherapy with Mitomycin C (MMC), 5FU and Ara-C. Later, progressive anemia, thrombocytopenia, renal dysfunction and elevation of serum LDH were recognized. A diagnosis of HUS was made. As they had no symptoms of infectious diseases or relapse of cancer, the cause of HUS was thought to be MMC. Treatment with antiplatelet drugs and fresh frozen plasma was effective for two patients. However, one patient died of pulmonary edema.

The effect of basic and acidic fibroblast growth factors (bFGF and aFGF) on the growth of leukemic blast progenitors in acute myelogenous leukemia

The effect of basic and acidic fibroblast growth factors on leukemic blast progenitors was studied in 14 patients with acute myelogenous leukemia and in one patient with chronic myelocytic leukemia in myeloid crisis. bFGF and aFGF stimulated blast-colony formation by leukemic blast progenitors cultured in methylcellulose in two patients. In the other 13 patients, no significant effect of either FGF on blast-colony formation was noted. The combination of bFGF or a FGF and G-CSF, GM-CSF, interleukin-3, or stem cell factor (SCF) had a synergistic effect on blast-colony formation in three patients. In the other patients, however, synergism between FGF and CSF was not detected. In fact, bFGF was found to suppress the stimulation of blast-colony formation due to GM-CSF in one of 10 patients and that due to SCF in four of eight patients. aFGF suppressed the stimulation of blast-colony formation due to GM-CSF in two of 11 patients and that due to SCF in four of eight patients. The results show that bFGF and aFGF do not directly play a major role in leukemic hematopoiesis but that they may modulate the cytokine network affecting leukemic cell growth.

Diversity and similarity in signaling pathways of hematopoietic growth factors in human leukemia cell lines

Diversity and similarity in signaling pathways of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and stem cell factor (SCF) in five human factor-responsive leukemia cell lines were investigated by immunoblotting to detect tyrosine phosphorylation of intracellular proteins. G-CSF induced tyrosine phosphorylation of a set of proteins with few different components according to the cell lines. IL-3 also induced phosphorylation of several proteins. In a lymphoid cell line, phosphorylation patterns induced by IL-3 were somewhat different from that in myeloid cell lines. Phosphorylation patterns by G-CSF and those by IL-3 were similar in myeloid cell lines. In a cell line which responded to both IL-3 and SCF, almost similar sets of proteins were phosphorylated by each, although phosphorylation of a 92-KDa protein was specific to IL-3 and that of a 140-200-KDa protein was specific to SCF. Taken together, proliferative growth factors induced tyrosine phosphorylation of similar sets of proteins with little difference according to each growth factor and each target cell line.

All-trans retinoic acid upregulates thrombomodulin and downregulates tissue-factor expression in acute promyelocytic leukemia cells: distinct expression of thrombomodulin and tissue factor in human leukemic cells

The expressions of thrombomodulin (TM) and tissue factor (TF) by all-trans retinoic acid (ATRA) were studied in human leukemic cell lines including NB4 (acute promyelocytic leukemia) and U937 (monoblastic leukemia). ATRA remarkably upregulated TM antigen expression in cell lysates as well as TM cofactor activity on the cell surfaces of NB4. The level of TM mRNA in NB4 cells was increased by ATRA. Inherently procoagulant NB4 cells contained markedly higher content of TF, which was efficiently reduced by ATRA. Modest increase of TM and decrease of TF were observed when NB4 cells were treated with dibutyryl cyclic adenosine monophosphate (dbcAMP). On the other hand, both ATRA and dbcAMP showed dramatic increase of TM antigen level and modest decrease of TF antigen in U937 cells. These results suggest that ATRA regulates expressions of TM and TF antigens and activity in NB4 and U937 cell lines, and provide evidence for a potential efficiency of ATRA as a preventive and therapeutic agent for disseminated intravascular coagulation in promyelocytic and monocytic leukemia.

The effects of retinoic Acid analogs on the blast cells of acute myeloblastic-leukemia in culture

The effects of retinoic acid (RA) analogues, Am80 and Ch55, on acute myeloblastic leukemia (AML) cells, acute promyelocytic leukemia (APL) cells, and normal bone marrow (BM) cells, were studied in vitro. These analogues have different binding affinity to RA receptors and cellular retinoic acid binding proteins (CRABP). All-trans RA (ATRA) showed various effects on the proliferation of AML cells and BM cells. These analogues showed similar effects. Regarding the differentiation of APL cells into neutrophils, Ch55 and Am80 were more potent than ATRA. Ch55, which does not bind to CRABP, may overcome the clinical problem of retinoid-resistance due to the induction of CRABP.

Modulation of growth factor receptors on acute myeloblastic leukemia cells by retinoic acid

The effects of retinoic acid (RA) on the proliferation of acute myeloblastic leukemia (AML) cells were studied. AML samples were divided into three groups. Namely, RA stimulated blast colony formation by AML samples in group A and inhibited that by the samples in group B, regardless of added growth factors. For the samples in group C, RA inhibited the colonies formed by granulocyte colony-stimulating factor (G-CSF) but stimulated those by granulocyte macrophage CSF (GM-CSF). To investigate the mechanism involved, the effects of RA on growth factor receptors on AML cells were examined by flow cytometry using fluorolabeled ligands. For the samples in groups A and B, RA affected neither G-CSF receptor (GR) nor GM-CSF receptor (GMR). For the samples in group C, exposure to 10(-7) M RA for 1 day clearly increased GMR, but did not affect GR. This finding supports the hypothesis that the increase of GMR is one of the causes of the stimulative effects of RA on cells cultured with GM-CSF in group C.

Successful treatment of refractory pure red cell aplasia by buserelin acetate

A 39-year-old female with autoimmune hemolytic anemia suffered from pure red cell aplasia. She received immunosuppressive agents including prednisolone, azathioprine, cyclophosphamide and methotrexate, resulting in a little improvement of the anemia for only short term. Consequently, she required multiple red cell transfusions for 3 years. She received buserelin acetate, a gonadotropin-releasing hormone analogue. Thereafter, the anemia dramatically improved. The direct effect of buserelin on hemopoietic progenitors was not detected in the in vitro culture study. It is most likely that buserelin enhanced erythropoiesis through the alteration of hormonal milieu. The usefulness of buserelin in the treatment of refractory pure red cell aplasia is discussed.

The role of stroma cells on the proliferation and C-kit expression of acute myeloblastic-leukemia cells

To examine the role of stroma cells on the proliferation and c-kit expression of acute myeloblastic leukemia (AML) cells, blast cells from patients were cultured with growth factors or on human marrow stroma cells. c-KIT protein detected by flow cytometry and the plating efficiencies of the cells cultured with growth factors decreased markedly, but those of the cells cultured on stroma cells were mostly preserved. Conditioned medium from the stroma cells and fibroblasts from fetal Sl/Sl mouse showed, to some extent, the same effects. The growth factors including kit ligand seemed to favor the terminal division more than the self renewal and stroma cells had the opposite tendency. Stoma cells may produce some factors other than kit ligand to maintain c-kit expression and high clonogenicity.

Growth potentiating activity of endogenous production of interleukin-1 and tumor necrosis factor alpha in blast cells of acute myeloblastic leukemia

For the optimal growth of clonogenic cells in acute myeloblastic leukemia (AML), several cytokines such as tumor necrosis factor alpha (TNF-alpha), interleukin-1 (IL-1) and IL-6 are required in addition to colony-stimulating factor (CSF), which may be produced by blast cells themselves. In the present study, we addressed the potential role of endogenous production of TNF-alpha and/or IL-1 in the in vitro growth of AML clonogenic cells supported by IL-3. Addition of a specific neutralizing antibody against TNF-alpha (anti-TNF-alpha) to the culture significantly reduced the growth-stimulating effect of IL-3 on the cells in 11 of 14 patients. Simultaneous addition of anti-IL-1 alpha and anti-IL-1 beta also partly affected the growth, although to a much lesser extent when compared to the effect observed with anti-TNF-alpha. In 3 patients, the growth-stimulating effect of IL-3 was completely abrogated by anti-TNF-alpha or a combination of all three antibodies. Constitutive TNF-alpha transcript was observed in 5 patients and TNF-alpha protein was present in culture supernatant. Following in vitro culture, a transient but profound increase in c-fos, c-jun, TNF-alpha and IL-1 beta mRNA levels was observed. Anti-TNF-alpha inhibited the accumulation of TNF-alpha transcript, suggesting that membrane-integrated TNF-alpha may be partly responsible for the induction of TNF-alpha mRNA. It seems likely that the accumulation of these genes occurs through a protein kinase C-independent signaling pathway.

Relationship between c-Kit expression and proliferation in acute myeloblastic leukemia cell lines

We have proposed that the transmembrane receptor encoded by the c-Kit protooncogene and its ligand play an important role in regulating the proliferation of blasts cells in acute myeloblastic leukemia (AML). To test this hypothesis, immunobeads were used to separate blasts from three Kit-expression positive cell lines into strongly Kit-protein positive and weakly Kit-protein positive fractions. The strongly positive fraction had greater proliferative potential than the weakly positive fraction as assessed both by colony-formation in methylcellulose and growth of clonogenic cells in suspension. The reproducibility of the percentage of each blast population found in the strongly and weakly positive fractions provided evidence that Kit-protein expression is regulated. Kinetic experiments provided evidence for reversible transitions between strong and weak Kit protein expression. Thus regulated expression of the Kit receptor may be a mechanism for controlling blast cell growth in culture.

The in vitro growth patterns and drug sensitivities of leukemic blast progenitors among the subtypes of acute myelocytic leukemia

The in vitro growth activities and drug sensitivities of leukemic blast progenitors were compared among the subgroups of acute myelocytic leukemia (AML) classified according to the French-American-British (FAB) cooperative group. Leukemic cells separated from the peripheral bloods of AML patients were cultured in methylcellulose media, and the plating efficiencies of primary colonies (PE1) and secondary colonies after replating (PE2) were determined. PE1 and PE2 have been considered to reflect the capacities of terminal divisions and self-renewal of leukemic blast progenitors, respectively. PE1 and PE2 were variable among AML patients; these findings suggest that AML is a heterogeneous disease in terms of the proliferative activities of leukemic cells. No significant correlation was noted between PE1 or PE2 and the AML subtype. The sensitivities to cytosine arabinoside (Ara-C) of leukemic blast progenitors were studied in methylcellulose and suspension cultures. Ara-C sensitivity was not significantly correlated with the AML subtype, either. In contrast, there was statistically significant correlation between PE2 and the remission outcome of the patients, whereas PE1 was not significantly associated with the clinical outcome. The results in the present study indicate that the proliferative activity, especially self-renewal capacity, of leukemic blast progenitors is highly predictive of the prognosis of AML patients but is not significantly correlated with the AML subtype classified by the blast morphology.

Comparison of the effects of all-trans and cis-retinoic acid on the blast stem cells of acute myeloblastic leukemia in culture

Recent work has shown that acute promyelocytic leukemia (APL) cells have a characteristic translocation involving the retinoic acid receptor on chromosome 17 and the myl protein on chromosome 15. Patients with APL respond to the administration of all-trans-retinoic acid. A cell line with t15;17 (NB4) has recently been reported; this line responds to all-trans-retinoic acid with differentiation. There is also a recent report showing that all-trans-retinoic acid is more active than cis-retinoic acid in inducing differentiation in freshly obtained APL cells. All-trans-retinoic and cis-retinoic acid are compared for their effects on growth in culture of freshly obtained AML cells, cell lines without t15;17, and NB4 cells. While all of these AML populations responded to both forms of retinoic acid, NB4 cells only were much more sensitive to all-trans-retinoic acid compared to cis-retinoic acid. The difference was seen when the NB4 cells were exposed in suspension and not when colony-formation in methylcellulose was used as an end point. Both forms of retinoic acid increased the sensitivity of blast cells to cytosine arabinoside; for NB4 cells, the sensitization was much greater when all-trans-retinoic acid was used rather than cis-retinoic acid. We conclude that the increased effects of all-trans-retinoic acid are specific for APL cells, and that a major effect of retinoic acid is on blast stem cell self-renewal.

[Lymphomatoid granulomatosis (LYG) occurring in a patient with follicular lymphoma during remission]

A 49 years-old man presented with dry cough, low grade fever, and abnormal shadow on a chest X-ray. He had suffered from follicular lymphoma of the liver 5 years previously. He received irradiation therapy in combination with chemotherapy for approximately three years and had been in complete remission. Physical and radiological examination revealed pleural effusion and softly dense masses in the right lung. The laboratory data were within normal limits. He was diagnosed as having lymphomatoid granulomatosis (LYG) by open lung biopsy. The lung lesion was mainly infiltrated with T cells. The patient received prednisolone and the lung lesions disappeared. However, when a lung mass was noted two months later, he started to receive combination chemotherapy consisting of cyclophosphamide, adriamycin, vincristine, and prednisolone every three months. He has not shown relapse of LYG so far. To investigate the association between the preceding follicular lymphoma and subsequent LYG at this time, DNA analysis using the PCR technique was carried out. The LYG lesion did not show a rearranged band for the JH probe, while the paraffin-embedded specimen of the preceding follicular lymphoma had shown rearranged band for the JH band. Southern blot analysis of the LYG lesion, showed no rearrangement for TCR beta, gamma or JH probe. These findings indicate that the LYG was different from the preceding follicular lymphoma in terms of origin. LYG is considered to be induced in the immunosuppressive state due to lymphoma.

Interleukin-6 reduces the optimal growth in vitro of leukemic blast progenitors from acute myeloblastic leukemia patients

The combined effects of five cytokines; recombinant human (rHu) granulocyte colony-stimulating factor (G-CSF), rHu granulocyte-macrophage colony-stimulating factor (GM-CSF), rHu interleukin-1 beta (IL-1 beta), rHu interleukin-3 (IL-3), and rHu interleukin-6 (IL-6) on blast colony formation in methylcellulose by leukemic blast progenitors from 10 patients with acute myeloblastic leukemia (AML) were studied. Combination of G-CSF, GM-CSF, IL-1 beta, and IL-3 stimulated maximum blast colony formation in 9 patients. Further addition of IL-6 reduced the combined effect of the four cytokines on blast colony formation. IL-6 regulates the proliferation of leukemic blast progenitors and may play an important role in the regulation of hematopoiesis.

Comparison of the proliferative activity and sensitivity to cytosine arabinoside of leukemic blast progenitors in acute myeloblastic leukemia at diagnosis and in relapse

To determine whether the biological characteristics of leukemic cells change after repeated chemotherapy, we compared the proliferative activity and drug sensitivity of leukemic blast progenitors in 7 patients with acute myeloblastic leukemia at diagnosis and in relapse. The proliferative activity of leukemic blast progenitors was assessed based on primary (PE1) and secondary (PE2) colony formation in methylcellulose culture and on the recovery of clonogenic cells in suspension culture. The effect of cytosine arabinoside (Ara-C) on leukemic blast progenitors was studied both in methylcellulose and in suspension cultures. PE1 and PE2 values varied among the patients. PE2 of 4 patients out of 7 patients became significantly higher in relapse than at diagnosis. The sensitivity to Ara-C of leukemic blast progenitors deteriorated in 5 patients in relapse. The results suggest that the biological nature in terms of proliferative activity and Ara-C sensitivity of leukemic blast progenitors may change in the clinical course after chemotherapy.

Pure red cell aplasia following autoimmune haemolytic anaemia. Cell-mediated suppression of erythropoiesis as a possible pathogenesis of pure red cell aplasia

We report here a rare case of pure red cell aplasia (PRCA) following autoimmune haemolytic anaemia (AIHA). After 4 years of AIHA, the patient developed anaemia with severe erythroid hypoplasia and was diagnosed as having PRCA. At this time, Coombs' test was negative and parvovirus infection was not recognized. The patient received azathioprine, and PRCA improved. To determine the pathogenesis of PRCA, in vitro culture studies of erythropoietic and granulopoietic precursors were performed. The patient's serum or IgG did not suppress the colony formation of bone marrow colony-forming units-erythroid (CFU-E) of normal subjects and the patient. In contrast, mononuclear cells in the peripheral blood of the patient significantly suppressed CFU-E of normal subjects. Media conditioned by the patient's mononuclear cells did not significantly suppress CFU-E. The significant production of suppressive cytokine such as tumour necrosis factor or gamma-interferon by the patient's mononuclear cells was not recognized. These findings suggest that the cytotoxic mononuclear cells affected directly the erythropoietic precursors and caused PRCA in this patient. The pathogenesis of PRCA was, therefore, considered to be different from that of the preceding AIHA.

Enhanced effect of mutant granulocyte-colony-stimulating factor (KW-2228) on the growth of normal and leukemic hemopoietic progenitor cells in comparison with recombinant human granulocyte-colony-stimulating factor (G-CSF)

We tested the in vitro effect of a novel granulocyte colony-stimulating factor (G-CSF) derivative (KW-2228) on the growth of G-CSF-dependent hemopoietic progenitor cells: granulocyte precursor cells (CFU-G), leukemic blast progenitors freshly obtained from 9 patients with acute myeloblastic leukemia (AML) and cells of a G-CSF-dependent human AML cell line (OCI/AML 1a). KW-2228 showed a higher stimulating effect than recombinant human G-CSF (rhCSF) on CFU-G; 3 out of 9 leukemic blast progenitors and OCI/AML 1a cells. The difference in biochemical stability between rhG-CSF and KW-2228 was considered to explain the superior colony-stimulating activity of KW-2228. The results show that KW-2228 will be a new granulopoietic factor.

Interactions between retinoic acid and colony-stimulating factors affecting the blast cells of acute myeloblastic leukemia

The responses to retinoic acid (RA) of acute myeloblastic leukemia (AML) blasts and normal hemopoietic progenitors was examined under defined growth factor conditions. For the leukemic cells marked patient to patient variation was seen; blast colony formation by cells from some patients was stimulated by RA without growth factors or in the presence of recombinant granulocyte colony-simulating factor (rG-CSF), recombinant granulocyte-macrophage-CSF rGM-CSF and recombinant interleukin-3 (rIL-3); for other populations inhibition was observed under the same conditions. Some blast cells were stimulated by RA in the presence of rGM-CSF and rIL-3 and inhibited when cultured with RA and rG-CSF. Supernatants prepared from blasts cultured with RA and growth factors did not show activities that were not readily explained by the carry-over of growth factors; this result did not provide evidence that RA and growth factors interact to produce factors. Titrations of RA showed that activity was first observed at concentrations of 10(-9) M and was maximum at concentrations of 10(-7) M. Different effects of RA in combination with rG-CSF compared with rGM-CSF or IL-3 were not seen when the cells were tested in suspension culture rather than in methylcellulose, a finding that may be interpreted to mean that the interaction between RA and factors affects terminally-dividing blast cells. Three normal bone marrow samples were cultured with RA and growth factors. Colony formation was stimulated by RA in the presence of rGM-CSF or rIL-3 but inhibited by RA with rG-CSF. Thus a differential effect of RA in combination with growth factors occurs in normal hemopoietic cells and persists in some AML populations.

Establishment of an interleukin-3-dependent leukemic cell line from a patient with chronic lymphocytic leukemia in the acute phase

A novel human leukemic cell line, TMD2, which proliferates dependently on interleukin-3 (IL-3), was established from the peripheral blood (PB) of a patient with chronic lymphocytic leukemia (CLL) in the acute phase. After 8 years of the chronic phase of CLL, lymphoblastoid cells appeared and became dominant in the PB. After repeated subcultures of the patient's PB cells in the acute phase, lymphoblastoid cells have proliferated actively in the presence of recombinant human IL-3, and the TMD2 cell line has been established. The lymphoblastoid cells in acute phase and TMD2 cells proliferated dependently on IL-3, whereas growth of the small lymphocytes in chronic phase was not supported by IL-3. Other ILs (IL-1, 2, and 4 through 6) or CSF did not support the growth or survival of TMD2 cells. The existence of high-affinity receptors for IL-3 was shown on TMD2 cells (binding sites 88 per cell, Kd = 76.9 pmol/L). DNA extracted from the small lymphocytes in the chronic phase, the lymphoblastoid cells in the acute phase, and TMD2 cells showed the same rearrangement pattern of the immunoglobulin heavy-chain gene. Therefore, these cells were considered to have originated from the same clone. These results imply that a genetic event that caused the responsiveness to IL-3 in the cell of the chronic phase caused the acute transformation of CLL in this patient. We consider that TMD2 cell line is valuable as a model of cells of CLL in the acute phase and as a tool for studying the signal transduction system of IL-3.

Effect of protein kinase inhibitors on the proliferation of leukemic cells stimulated by granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor or interleukin-3

The effects of the inhibitor for protein kinase A or C, or tyrosine kinase (H-8, staurosporine, or genistein, respectively) on the proliferation of leukemic and normal bone marrow cells stimulated by granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), or interleukin-3 (IL-3) were studied using the MTT assay. These inhibitors suppressed the proliferation of leukemic and normal bone marrow cells in a dose-dependent manner. Although the suppressive effect of each inhibitor on cell proliferation was varied in each instance, the effects were almost similar whichever CSF was added. A significant difference was not recognized between leukemic and normal bone marrow cells in terms of sensitivity to these inhibitors. The data indicate that protein kinase inhibitors have an inhibitory effect on leukemic and normal hematopoietic cell proliferation and that further studies are required to determine if this effect is due to the inhibition of protein kinases acting as the second messenger of CSFs.

The in vitro effect of vincristine on the blast cell renewal in acute myeloblastic leukemia

The goal of chemotherapy for acute myeloblastic leukemia (AML) may only be achieved by eradicating the self-renewal capacity of the blast progenitors. In this regard, chemotherapeutic drugs should be screened according to their effects against self-renewal. The present report was aimed to study the effect of the vinca alkaloid, vincristine (VCR), on the terminal divisions and self-renewal of the blast progenitors. A primary colony assay was utilized to reflect the former and a secondary colony assay and suspension culture to reflect the latter in AML patients. The results indicated that in many of the cases studied, VCR was considered to be almost equally toxic to terminal divisions and self-renewal of the blast progenitors. An almost equivalent cytotoxicity of VCR was also noted against normal hematopoietic cells, assessed by colony-forming unit granulocyte-macrophage (CFU-GM) assay. This study suggested that successful chemotherapy with VCR may be more easily achieved in combination with other drugs that are highly inhibitory to the self-renewal of the blast progenitors.

Enhancement by transforming growth factor-beta 1 (TGF-beta 1) of the proliferation of leukemic blast progenitors stimulated with IL-3

We studied the effect of transforming growth factor-beta 1 (TGF-beta 1) on colony formation of leukemic blast progenitors from ten acute myeloblastic leukemia (AML) patients stimulated with granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), interleukin-6 (IL-6), or interleukin-1 beta (IL-1 beta). These CSFs and interleukins by themselves stimulated the proliferation of leukemic blast progenitors without adding TGF-beta 1. G-CSF, GM-CSF, and IL-3 stimulated blast colony formation in nine patients, IL-6 stimulated it in five, and IL-1 beta stimulated in four. TGF-beta 1 significantly reduced blast colony formation stimulated by G-CSF, GM-CSF, or IL-6 in all patients. In contrast, TGF-beta 1 enhanced the stimulatory effect of IL-3 on blast progenitors from three cases, while in the other seven patients TGF-beta 1 reduced blast colony formation in the presence of IL-3. To study the mechanism by which TGF-beta 1 enhanced the stimulatory effect of IL-3 on blast progenitors, we carried out the following experiments in the three patients in which it occurred. First, the media conditioned by leukemic cells in the presence of TGF-beta 1 stimulated the growth of leukemic blast progenitors, but such effect was completely abolished by anti-IL-1 beta antibody. Second, the addition of IL-1 beta in the culture significantly enhanced the growth of blast progenitors stimulated with IL-3. Third, leukemic cells of the two patients studied were revealed to secrete IL-1 beta and tumor necrosis factor-alpha (TNF-alpha) constitutively; the production by leukemic cells of IL-1 beta and TNF-alpha was significantly promoted by TGF-beta 1. Furthermore, the growth enhancing effect of TGF-beta 1 in the presence of IL-3 was fully neutralized by anti-IL-1 beta antibody. These findings suggest that TGF-beta 1 stimulated the growth of blast progenitors through the production and secretion of IL-1 beta by leukemic cells.

Antiproliferative and differentiative effects of recombinant interleukin-4 on a granulocyte colony-stimulating factor-dependent myeloblastic leukemic cell line

The effect of recombinant human interleukin-4 (IL-4) on a granulocyte colony-stimulating factor (G-CSF)-dependent human myeloblastic leukemic cell line, OCI-AML1a, was investigated. IL-4 suppressed the clonogenic cell growth in methylcellulose culture, inhibited the uptake of 3H thymidine in a dose-dependent manner at 5 to 100 U/mL, and consequently suppressed the growth of clonogenic cells in short- and long-term suspension cultures. In addition, IL-4 markedly increased the number of adherent cells. These adherent cells were alpha-naphthyl-butyrate (alpha-NB) esterase-positive and showed macrophage-like appearance, increased expression of CD14, CD11b, CD23, and Ia, and significantly decreased clonogenicity. On the other hand, nonadherent cells growing in suspension showed only slight increase in proportion of alpha-NB esterase-positive or monocyte/macrophage-like cells and increased CD23 expression by an addition of IL-4. The clonogenicity of the nonadherent cells was not significantly influenced by IL-4. By addition of the media conditioned by OCI-AML1a cells in the presence of IL-4, the clonogenic cells growth of OCIAML1a cells was suppressed and adherent cells were markedly increased. The suppressive and differentiative effects on OCI/AML1a cells of the conditioned media and IL-4 itself were almost completely abolished by anti-IL-4 antibody. Furthermore, the neutralizing antibodies against transforming growth factor-beta 2 (TGF-beta 2), tumor necrosis factor-alpha (TNF-alpha), or IL-6 did not influence the effect of recombinant IL-4. Taken together, IL-4 was shown to suppress the growth and induce differentiation toward adherent macrophage-like cells of the G-CSF-dependent myeloblastic cell line. The effect of IL-4 may be direct, and not secondary via inducing production of other cytokines such as TGF-beta, TNF-alpha, or IL-6 by leukemic cells.

Effects of recombinant interleukin 4 on the growth and differentiation of blast progenitors stimulated with G-CSF, GM-CSF and IL-3 from acute myeloblastic leukaemia patients

The effects of human recombinant interleukin 4 (rIL-4) on the growth of leukaemic blast progenitors were investigated. Cells obtained from 20 acute myeloblastic leukaemia (AML) patients were evaluated using the blast colony assay in methylcellulose and suspension cultures. While rIL-4 by itself did not show any colony stimulatory activity in the blast colony assay, it suppressed the blast colony formation in methylcellulose stimulated with G-CSF, GM-CSF or IL-3 in 14 patients. In another six patients, rIL-4 enhanced blast colony growth in four patients or did not show any significant effect with any CSF in two patients. In suspension cultures of 12 cases studied, the effects of rIL-4 on the clonogenic cell recoveries were essentially similar to the results of the blast colony assay in each case. In three patients, rIL-4 augmented the differentiation of the leukaemic cells to monocyte lineage. Further, the clinical outcome was significantly different between the patients whose blast progenitors were stimulated by rIL-4 and the patients whose blast progenitors were suppressed by rIL-4 (P less than 0.05); three out of four patients in the former group failed in achieving complete remission (CR), while 12 out of 14 patients in the latter group achieved CR. The results show that the effects of IL-4 on leukaemic blast progenitors were diverse and the responsiveness to IL-4 may be correlated with the prognoses of the patients.

Effects of N4-behenoyl-1-beta-D-arabinofuranosylcytosine on blast progenitors of acute myeloblastic leukemia

To determine the antileukemic effect of N4-behenoyl-1-beta-D-arabinofuranosylcytosine (BH-AC), a synthetic masked compound of 1-beta-D-arabinofuranosylcytosine, the pharmacokinetics and suppressive effect on leukemic blast progenitors of BH-AC were studied. When BH-AC was added to the suspension culture of leukemic cells, BH-AC gradually decreased in concentration in the culture media and was rapidly taken into the cellular fraction. The conversion from BH-AC to 1-beta-D-arabinofuranosylcytosine was noted in both the culture media and the cellular fraction. The concentration of 1-beta-D-arabinofuranosylcytosine converted from BH-AC in the culture medium gradually increased during 7 days of culture, although the rate of conversion was variable among the samples. BH-AC suppressed primary and secondary blast colony formation in a dose responsive manner. BH-AC also suppressed the recovery of clonogenic cells in suspension culture. The suppression by BH-AC was more prominent in secondary blast colony formation and the recovery of clonogenic cells in suspension culture than in primary blast colony formation. Secondary blast colony formation and the recovery of clonogenic cells in suspension are considered to reflect the self-renewal of blast progenitors, while primary blast colony formation is considered to reflect the terminal divisions of blast progenitors. The results obtained in the present study suggest that BH-AC is more effective to suppress the self-renewal of blast progenitors than the terminal divisions. The findings offer a theoretical basis in the utility of BH-AC in the therapy of acute myeloblastic leukemia.

Effects of interleukin-6 and granulocyte colony-stimulating factor on the proliferation of leukemic blast progenitors from acute myeloblastic leukemia patients

The effects of recombinant human interleukin-6 (rh IL-6), which has homology with rh granulocyte colony-stimulating factor (rh G-CSF) at the amino acid sequence level, and rh G-CSF on normal human bone marrow cells, fresh leukemic blast progenitors from 16 acute myeloblastic leukemia (AML) patients, and G-CSF-dependent human AML cell line (OCI/AML 1a) were investigated. rh G-CSF stimulated the proliferation of leukemic blast progenitors from 13 out of 16 AML patients tested. rh IL-6 stimulated the proliferation of blasts from eight AML patients and enhanced the G-CSF-dependent proliferation of the fresh AML blasts from two out of eight patients tested. On the other hand, rh IL-6 suppressed the blast colony formation from two AML patients and OCI/AML 1a cells and also reduced the G-CSF-dependent proliferation of the blast progenitors from one of the two patients and the cell line, rh IL-6 had no effect on the colony formation of normal granulocyte-macrophage colony-forming units (CFU-GM) with or without rh G-CSF. Differentiation-induction by rh IL-6 was not observed in the fresh AML blasts but was observed in OCI/AML 1a. The effect of IL-6 on the blast colony formation and G-CSF-dependent blast cell growth was complicated and heterogenous among the AML cases; IL-6 stimulated blast colony formation in some cases and suppressed it in others. The heterogeneity of the response was supposed to be derived from the heterogeneity of the characteristics of AML cells. Although G-CSF simply stimulated the blast colony formation, IL-6 had a bimodulatory effect on the proliferation of leukemic blast progenitors from AML patients. IL-6 might be involved in the regulation of the proliferation of AML cells in vivo as well as in vitro.

Richter syndrome with two B cell clones possessing different surface immunoglobulins and immunoglobulin gene rearrangements

A patient with two populations of B cell malignancy in the bone marrow is reported. One population consisted of mature small lymphocytes, expressing surface IgM + D, lambda and proliferating very slowly. The other population consisted of abnormal large lymphoid cells, expressing surface IgM, K and proliferating actively. We considered the former as chronic lymphocytic leukemia cells and the latter as malignant lymphoma cells. Therefore, this case was considered as Richter syndrome. The analysis of immunoglobulin heavy chain gene rearrangement showed the different patterns between the two populations. It suggested that the two populations arose from the different origins. We discussed the genetic relationship between the two clones of Richter syndrome referring to other reported cases.

[Acute myeloblastic leukemia and hepatocellular carcinoma following Waldenström's macroglobulinemia]

A 54-year-old man was admitted to our hospital for precise examination of pancytopenia in October 1988. He had been cut off his left femur and irradiated because of osteosarcoma in 1954. After 30 years, he was diagnosed as Waldenström's macroglobulinemia. Melphalan had been given 2 mg daily for 19 months until August 1988, when it was discontinued due to pancytopenia. Peripheral blood showed Hb 6.6 g/dl, platelet 40 x 10(3)/microliters, and WBC 2000/microliters with 33% blasts. Bone marrow showed normocellularity with 36% blasts. Although blasts were negative for peroxidase staining, surface marker analysis revealed myeloid (CD 13, CD 33) phenotypes. Chromosome analysis showed 45, XY, -7, inv (3). A CT scan of the liver showed a mass, 10 by 10 cm, compatible with hepatocellular carcinoma. He was treated with very low dose Ara-C without noticeable effect. Hepatic tumor gradually enlarged, and he died of hepatic failure. This is a rare case of quadruplicate malignancies. The chromosomal abnormality suggests that AML was secondary leukemia which might be associated with immunosuppression due to macroglobulinemia and/or melphalan therapy.

Successful treatment of a patient with posthepatitic severe aplastic anemia with bolus methylprednisolone

A 31-year-old female developed severe aplastic anemia following acute non-A non-B hepatitis. Because of the impossibility of bone marrow transplantation, bolus methylprednisolone therapy was done. Soon after the therapy, pancytopenia improved. She has since taken mepitiostane and no longer needs blood transfusions. Good response to the immunosuppressive therapy suggests that the pathogenesis of this anemia is related to the immune system. In vitro culture demonstrated that the patient's serum contained a factor which suppressed hematopoietic activity, possibly gamma-interferon.

Haematopoietic suppressing activity of gamma-interferon in serum and bone marrow of aplastic anaemia patients

To determine the mechanism by which haematopoiesis is suppressed in aplastic anaemia, the effect of the sera from 6 patients on the granulopoietic precursors (colony-forming units in culture; CFU-C) was studied in vitro. Addition of the sera from 2 patients significantly suppressed CFU-C. The suppressive effect of the sera on CFU-C was inhibited by the addition of 1.5 NU/ml of anti-gamma-IFN antibody. In another patient, anti-gamma-IFN antibody increased autologous CFU-C although the serum of the patient did not suppress CFU-C. Serum gamma-IFN levels of all patients were under 2 IU/ml. The above findings suggest that humoral factors inhibit haematopoiesis in some patients with aplastic anaemia, and that gamma-IFN plays a role as an inhibitor even at a low concentration.

Effect of platelet-derived growth factor on the proliferation of blast progenitors from acute myeloblastic leukemia patients

The effect of platelet-derived growth factor (PDGF) on self-renewal and terminal divisions of blast progenitors of acute myeloblastic leukemia was studied. The terminal divisions of blast progenitors were determined as the primary blast colony formation in methylcellulose culture; self-renewal was assessed by secondary colony formation by replating in methylcellulose and the recovery of clonogenic cells in suspension culture. PDGF neither enhanced nor suppressed primary or secondary blast colony formation in methylcellulose culture nor recovery of clonogenic cells in suspension. The results show that PDGF does not affect the self-renewal or terminal divisions of leukemic blast progenitors.