Role of p53 in hematopoietic recovery after cytotoxic treatment

Prompt reconstitution of hematopoiesis after cytoreductive therapy is essential for patient recovery and may have a positive impact on long-term prognosis. We examined the role of the p53 tumor suppressor gene in hematopoietic recovery in vivo after treatment with the cytotoxic drug 5-fluorouracil (5-FU). We used p53 knock-out (p53-/-) and wild-type (p53+/+) mice injected with 5-FU as the experimental model. Analysis of the repopulation ability and clonogenic activity of hematopoietic stem cells (HSCs) and their lineage-committed descendants showed a greater number of HSCs responsible for reconstitution of lethally irradiated recipients in p53-/- bone marrow cells (BMCs) recovering after 5-FU treatment than in the corresponding p53+/+ BMCs. In post-5-FU recovering BMCs, the percentage of HSC-enriched Lin- Sca-1(+) c-Kit+ cells was about threefold higher in p53-/- than in p53+/+ cells. Although the percentage of the most primitive HSCs (Lin- Sca-1(+) c-Kit+ CD34(low/-)) did not depend on p53, the percentage of multipotential HSCs and committed progenitors (Lin- Sca-1(+) c-Kit+ CD34(high/+)) was almost fourfold higher in post-5-FU recovering p53-/- BMCs than in their p53+/+ counterparts. The pool of HSCs from 5-FU-treated p53-/- BMCs was exhausted more slowly than that from the p53+/+ population as shown in vivo using pre-spleen colony-forming unit (CFU-S) assay and in vitro using long-term culture-initiating cells (LTC-ICs) and methylcellulose replating assays. Clonogenic activity of various lineage-specific descendants was significantly higher in post-5-FU regenerating p53-/- BMCs than in p53+/+ BMCs, probably because of their increased sensitivity to growth factors. Despite all these changes and the dramatic difference in sensitivity of p53-/- and p53+/+ BMCs to 5-FU-induced apoptosis, lineage commitment and differentiation of hematopoietic progenitors appeared to be independent of p53 status. These studies suggest that suppression of p53 function facilitates hematopoietic reconstitution after cytoreductive therapy by: (1) delaying the exhaustion of the most primitive HSC pool, (2) stimulating the production of multipotential HSCs, (3) increasing the sensitivity of hematopoietic cells to growth factors, and (4) decreasing the sensitivity to apoptosis.

Lymphocyte phenotyping in systemic sclerosis: a flow cytometry analysis of lymphocytes in bronchoalveolar lavage fluid

OBJECTIVE

Patients with scleroderma (systemic sclerosis [SSc]) frequently develop interstitial lung disease. The purpose of this work was to evaluate the cell profile in the bronchoalveolar lavage fluid (BALF) in patients suffering from a diffuse form of systemic sclerosis as compared with healthy controls.

STUDY DESIGN

Bronchoalveolar lavage was carried out in the right middle lobe of 25 untreated, nonsmoking patients with SSc and 12 healthy, nonsmoking volunteers. For the analysis of lymphocyte subsets, the following monoclonal antibodies were used: anti-CD3, anti-CD4, anti-CD8, anti-CD14, anti-CD16, anti-CD19, anti-CD25, anti-CD45, anti-CD56. Also, anti-HLA-DR and flow cytometry were used.

RESULTS

We found an increase in the total number of cells with an increase in the percentage of lymphocytes and neutrophils in BALF from patients when compared with controls (P < .05). The proportion of lymphocytes, cytotoxic/suppressor CD8+ and activated lymphocytes T CD25+ were higher in patients' BALF (P < .05). The CD4+/CD8+ ratio in BALF from subjects was significantly lower than in controls. These findings were characteristic of patients with early-stage disease.

CONCLUSION

Analysis of the BALF lymphocyte phenotype may be useful in the early detection of lung involvement in patients with SSc.

Treatment of Philadelphia leukemia in severe combined immunodeficient mice by combination of cyclophosphamide and bcr/abl antisense oligodeoxynucleotides

BACKGROUND

Philadelphia cells are human chronic myelogenous leukemia (CML) cells that contain the BCR/ABL oncogene (a fusion of the BCR and ABL genes). Selective eradication of these cells in vitro can be achieved by combined treatment with antisense phosphorothioate oligodeoxynucleotides ([S]ODNs) specifically targeted to this oncogene (bcr/abl [S]ODNs) and a suboptimal (for use as a single agent) dose of mafosfamide (the in vitro active form of cyclophosphamide).

PURPOSE

We evaluated the ability of bcr/abl antisense [S]ODNs, alone or subsequent to treatment with a single injection of cyclophosphamide, to suppress the leukemic process induced in severe combined immunodeficient (SCID) mice by Philadelphia cells (i.e., primary CML-blast crisis [CML-BC] cells). In addition, we studied potential mechanisms that might explain the efficacy of the bcr/abl antisense [S]ODN-mafosfamide combination against Philadelphia cells in vitro.

METHODS

The effects of treating leukemic mice with cyclophosphamide (25 mg/kg body weight; 25% of the dose required to eradicate evidence of leukemia in SCID mice) and/or bcr/abl antisense [S]ODNs were assessed by analysis of survival, by examination of bone marrow for the presence of leukemia cells (using a colony formation assay or using coupled reverse transcription and the polymerase chain reaction to screen for bcr/abl messenger RNA), and by examination of a variety of tissues for the presence of infiltrating leukemia cells. The induction of apoptosis (a cell death program) in vitro in primary CML-BC cells following treatment with bcr/abl antisense [S]ODNs plus or minus prior treatment with mafosfamide was monitored by use of a commercial assay. Relative cellular uptake of [S]ODNs by CML-BC cells treated in vitro with or without prior treatment with mafosfamide was determined by use of confocal microscopy and flow cytometry (for fluorescent [S]ODNs) or by use of blotting techniques that employed radioactively labeled probes (for extracted, unlabeled [S]ODNs). Levels of specific proteins in treated and untreated cells were determined by use of western blotting methods. Reported P values are two-sided.

RESULTS

The disease process in leukemic mice was retarded substantially by combination treatment with cyclophosphamide and specific bcr/abl antisense [S]ODNs (P < .001, relative to treatment with specific antisense [S]ODNs alone, cyclophosphamide alone, or cyclophosphamide plus nonspecific [i.e., control] antisense [S]ODNs); 50% of the mice treated with cyclophosphamide and specific antisense [S]ODNs appeared to be cured of leukemia. The combination treatment was associated with increased induction of apoptosis. In addition, cellular uptake of bcr/abl antisense [S]ODNs appeared to be increased twofold to sixfold by prior treatment with mafosfamide. This increased uptake of [S]ODNs was associated with enhanced suppression of p210bcr/abl protein levels.

CONCLUSIONS AND IMPLICATIONS

Combination therapy with antisense [S]ODNs targeted to specific oncogenes and less toxic doses of anticancer drugs may represent a rational strategy to purpose for the treatment of human leukemias.

Apoptosis induced in L1210 leukaemia cells by an inhibitor of the chymotrypsin-like activity of the proteasome

Of a number of factors involved in apoptosis, protease activity may play a crucial role. We show that N-benzyloxycarbonyl-Ile-Glu( O-t-butyl)-Ala-leucinal (PSI), a selective inhibitor of the chymotrypsin-like activity of the proteasome, induces massive apoptosis in murine leukaemia L1210 cells. At 50 nM concentration, PSI induces a block of cytokinesis, while higher concentrations (500 nM) cause S phase block and massive apoptosis. Z-Leu-leucinal, a specific calpain inhibitor, did not induce apoptosis. In contrast to previous reports, TNF-alpha did not enhance apoptosis when combined with PSI. Our results suggest that proteasome inhibitors may be considered as potential anti-neoplastic agents.

Populations of thymocytes and peripheral blood leucocytes in leukaemia-bearing mice treated with G-CSF

The influence of granulocyle-colony stimulating factor (G-CSF) on thymocyte subsets and peripheral blood leucocytes in leukaemia L1210-bearing mice was evaluated. Leukaemia-bearing mice have a markedly reduced L3T4+Lyt2+ thymocyte subpopulation. We observed "correction" of relative values of thymocyte subpopulations induced by treatment of mice with a G-CSF preparation. The suggestion is presented that this could result from liberation of lymphocyte T precursor cells from the bone marrow and increased homing of them into the thymus. The direct or indirect influence of G-CSF on the L3T4+Lyt2+ subpopulation of thymocytes is discussed.

[Plasma prekallikrein in chronic liver diseases]

Plasma prekallikrein (PPK) is a single-chain glycoprotein synthesized in the liver. The aim of our study was to evaluate a plasma prekallikrein as the marker reflecting liver protein synthesis in patients with chronic liver diseases. PPK levels have been measured by own modification of amidolytic micro-assay in 43 patients with chronic liver diseases and 37 healthy volunteers as control group. As compared to control group, PPK level was significantly decreased in patients with chronic active hepatitis and with decompensated liver cirrhosis and significantly increased in patients with liver cirrhosis complicated by hepatocellular carcinoma. There was no difference in plasma prekallikrein between patients with compensated liver cirrhosis and controls. The results suggest that PPK might be a useful index for the assessment of residual functional liver mass in patients with chronic liver diseases.

Synthesis of novel, aminoalkanolic derivatives of 5,7-dihydroxy-2-phenylbenzopyran-4-on as the potential cytostatic agents

The 7-(2,3-epoxypropoxy)-2-phenyl-5-hydroxy-4H-benzopyran-4-on and its aminoalkanolic derivatives were prepared as the potential cytostatic (antileukemic) compounds. They were tested in vivo on mice leukemia L1210.

[Elevated plasma prekallikrein level in patients with diabetes]

The contact activation of intrinsic pathway in the coagulation system accompanied by plasma kallikrein-induced kinin generation is thought to be involved in the pathogenesis of diabetic retinopathy. Plasma prekallikrein (PPK), a proenzyme of plasma kallikrein, is a single-chain glycoprotein synthesized mainly in the liver. The aim of our study was to evaluate plasma prekallikrein level in diabetic patients and to examine the relationship between PPK and the metabolic control of diabetes and development of retinopathy. In 53 diabetic patients and 33 healthy subjects as controls the following parameters have been assessed: plasma prekallikrein, serum fructosamine, glycated haemoglobin HbA1c, prothrombin time, partial thromboplastin time and antithrombin III (AT III). Compared to the control group, PPK level was significantly higher in diabetics, especially in patients with proliferative retinopathy. The significant positive correlations have been found between PPK and HbA1c in diabetic patients and between PPK and serum fructosamine concentration but only in diabetics without retinopathy. No differences in prothrombin time and AT III have been observed between diabetics and healthy subjects. A suggestion is presented on increase of plasma prekallikrein level in diabetics due to hyperglycaemia-stimulated glycoprotein over-synthesis in the liver, what would confirm the role of kallikrein-kinin system in the pathogenesis of microangiopathy.

Plasma prekallikrein levels in patients with hepatocellular carcinoma and liver cirrhosis: a pilot study

The concentration of plasma prekallikrein (PK) in five patients with hepatocellular carcinoma (HCC) has been measured and related to levels in 18 patients with liver cirrhosis (LC) and 30 healthy subjects. It was found that the mean PK level was significantly increased in patients with HCC, while patients with LC demonstrated lower concentrations, as compared with healthy subjects. The results indicate that PK might be useful in screening cirrhotic patients for HCC. Longitudinal studies of PK in a larger group of patients at risk of developing HCC are therefore recommended.

Early induction of immune resistance against leukemia in mice after lethal irradiation followed by syngeneic bone marrow transplantation and injection of syngeneic leukocytes

BALB/cxDBA/2Wf F1 (CD2F1) mice were lethally irradiated and reconstituted with syngeneic bone marrow cells untreated or treated with 75 micrograms/ml of mafosfamide. One day after bone marrow transplantation some groups of mice were injected with syngeneic splenocytes, peripheral blood leukocytes, or thymocytes. Seven days after marrow grafting the anti-L1210 leukemia immunization of mice, consisting of four i.p. injections of 10(6) L1210-Maf cells (L1210 cells treated in vitro with mafosfamide for inhibition of their growth in vivo), was started. Strong resistance against leukemia could be obtained only in mice receiving splenocytes or peripheral blood leukocytes, not in mice injected with thymocytes or in those not receiving any cells. In vitro elimination of various subpopulations from among the splenocytes before their injection into the mice made it possible to deduce which are necessary for early induction of antitumor resistance after bone marrow transplantation in mice. These cells are: Thy 1.2-, Ig-, AsGM 1-, Mac 1+, 1-Ad+/-, are adherent and nonsusceptible to carrageenan toxicity.

Return of immunohematopoietic impairment a long time after murine syngeneic bone marrow transplantation

We have tested the immunologic status and hematologic parameters of mice 2 months (short-term survivors) or 18 months (long-term survivors) after lethal total body irradiation and syngeneic bone marrow transplantation (SBMT), and of normal mice of corresponding age. Long-term SBMT survivors showed significantly lowered bone marrow and spleen cellularities, decreased numbers of CFU-S in hemopoietic organs and severe impairment in the formation of CFU-F colonies compared with short-term SBMT survivors and normal mice. The peripheral blood parameters (hematocrit, erythrocytes, reticulocytes, platelets, white blood cells and granulocyte counts), however, remained unaltered. In long-term SBMT survivors we also observed a relative increase of Lyt-2+ lymphocytes (CD8+, cytotoxic/suppressor) and Mac-1+ cells among splenocytes. At the same time the L3T4+/Lyt-2+ ratio (CD4+/CD8+) was decreased. Relative contents of Ig+, Thy-1+ and L3T4+ cells were unchanged. The ability of splenocytes to generate IL-2R+ cells after in vitro stimulation with concanavalin A was greatly diminished. In summary, the immunohematopoietic status after initial normalization is again impaired in long-term SBMT survivors.

Early induction of immune resistance against leukemia in lethally total body irradiated mice reconstituted with syngeneic bone marrow cells obtained from previously immunized donor mice

BALB/c x DBA/2 F1 (CD2F1) mice were lethally irradiated and reconstituted with syngeneic bone marrow cells (SBMC) obtained from normal or previously immunized (against L1210 lymphatic leukemia) donors. These recipient mice are called TBI + SBMT or TBI + Imm-SBMT mice, respectively. TBI + Imm-SBMT, but not TBI + SBMT mice, were able to develop strong immune resistance against L1210 leukemia, but not against MOPC 104E plasmacytoma, if the immunization procedure (four i.p. injections at weekly intervals of immunogenic L1210 cells) was started as early as 7 days posttransplantation. Incubation of Imm-SBMC with mafosfamide (ASTA Z7654) before grafting abrogated the ability of the recipient mice to develop early resistance against the leukemia. Treatment of Imm-SBMC with monoclonal or polyclonal antibodies plus complement showed that two or three subpopulations of Imm-SBMC were necessary for the transfer of immune information against leukemia: T lymphocytes with phenotype Thy 1.2+, Lyt 1+2-, I-Ad-, macrophages with phenotype Mac-1+, I-Ad-, and probably asialo-GM 1+ cells. Recipient mice immunized against L1210 leukemia before TBI + SBMT do not develop early resistance to the leukemia.

Successful adoptive immunotherapy of minimal residual disease after chemoradiotherapy and transplantation of bone marrow purged of leukaemia with mafosfamide

The effectiveness of adoptive immunotherapy in eliminating minimal residual disease in tumour-bearing mice after bone marrow transplantation was tested. This model mimics the human clinical condition when autologous bone marrow was purged ex vivo of leukaemia with mafosfamide or was not purged, and stored in liquid nitrogen before transplantation. Animals with minimal residual disease were prepared with marrow-ablative but leukaemia-noncurative doses of cyclophosphamide (CY) and total body irradiation followed by bone marrow transplantation. The next day after transplantation the recipients were injected with splenocytes immunized against the leukaemia cells (Imm-SPL) or monoclonal antibody (mAb). All the control mice died from leukaemia relapse, but 51% of purged bone marrow recipients, which received Imm-SPL, were cured. In similar conditions mAb did not exert a therapeutic effect. Imm-SPL were not able to eradicate minimal residual disease in the recipients of nonpurged bone marrow. Thus, in an animal model, we demonstrated that purging of bone marrow before grafting seems to be indispensable for successful adoptive immunotherapy of minimal residual disease (MRD) after autologous bone marrow transplantation.

The kinetics of immunologic and hematologic recovery in mice after lethal total body irradiation and reconstitution with syngeneic bone marrow cells treated or untreated with mafosfamide (ASTA Z 7654)

The immunohematopoietic reconstitution of mice lethally irradiated (TBI) and reconstituted with syngeneic bone marrow cells untreated or treated with mafosfamide (ASTA Z 7654) [TBI + SBMT or TBI + SBMT-Maf mice, respectively] was examined. The number of CFU-S was greatly reduced in TBI + SBMT-Maf mice compared with those in TBI + SBMT mice. The recovery of blood parameters (hematocrit, reticulocytes, erythrocytes, white blood cells, granulocytes, platelets) and of bone marrow and spleen cells, but not of peritoneal exudate cells, was slightly delayed in TBI + SBMT-Maf mice compared with those in TBI + SBMT mice. The time for immune system regeneration was, however, considerably longer in TBI + SBMT-Maf than in TBI + SBMT mice, as measured by the incidence of Ig+, Thy-1.2+, L3T4+, Lyt-2+, and IL-2R+ cells in the spleens. The appearance of Mac-1+ and asialo-GM 1+ cells was only slightly prolonged or unchanged, respectively.

Successful chemoimmunotherapy of murine L1210 lymphatic leukemia with cyclophosphamide and mafosfamide-treated leukemia cells

Balb/c x DBA/2 F1 mice (CD2F1 mice) bearing L1210 lymphatic (10 L1210 cells i.p. injected on day 0) were subjected to chemoimmunotherapy. They received 100 mg/kg of cyclophosphamide i.p. on day +8 and 10(6) or 10(7) immunogenic L1210 cells treated in vitro with mafosfamide - ASTA Z7654 (L1210-Maf cells) i.p. or i.p. + s.c. on days 0, +3, +6, +9, +12 after the leukemia implantation. About 30% of leukemia-bearing mice receiving cyclophosphamide and L1210-Maf cells after L1210 inoculation were able to reject the leukemia (as compared with 0% after injection of L1210-Maf cells only or 5% after cyclophosphamide administration). Better results (54% of cured mice) were obtained if 10(7) L1210-Maf cells were injected i.p. +s.c. beside cyclophosphamide. Biological response modifiers (BRM's): levamisole, BCG, bestatin did not improve these results in the doses used in the experiment. Augmentation of anti-L1210 therapeutic response is dependent on the administration of cyclophosphamide and L1210-Maf cels. Cyclophosphamide not only reduces the tumor burden but probably can potentiate the L1210-Maf dependent antitumor immunity as well.

Cytochemical characterization of mouse L1210 leukemia

Mouse lymphatic leukemia L1210 cells were characterized with polyclonal and monoclonal antibodies and lectins. The cells were found to have the phenotype IgG-, Thy-1.2-, Lyt-1-, Lyt-2-, asialo-GM1-, TL-, I-Ad-, IL-2R+, peanut agglutinin+, and Helix pomatia lectin +/-. They retained expression of H-2Kd and H-2Dd. Thus, these cells resemble "null" cells.

Mechanisms of immunological response induced in CD2F1 mice by administration of semisyngeneic L 1210 leukemia cells treated with cyclophosphamide

CD2F1 mice were immunized against semisyngeneic L 1210 leukemia. Immunization was achieved by four i.p. injections, in weekly intervals, of L 1210 cells treated in vivo twice with 200 mg/kg of cyclophosphamide. The immunized animals survived i.p. challenge with 1000 untreated L 1210 cells that was lethal for nonimmunized mice. The immunity could be abrogated in vivo with anti-mouse thymocyte serum, carrageenan or reserpine, but not by anti-mouse IgG serum, suggesting participation of T lymphocytes and macrophages in the response. Moreover, lymphocytes and macrophages from the peritoneal cavity of immunized mice were cytotoxic in vitro for L 1210 cells. The immunity, at least partially, could be adoptively transferred with peritoneal exudate cells or splenocytes.

Preparation and some properties of highly purified human serum kallikrein

A 3000--6000-fold purified kallikrein was obtained from human serum in 10--25% yield by chromatography on QAE-Sephadex A-50, Molselect CM-50 and on soybean trypsin inhibitor (SBTI)-AH-Sepharose 4-B. The enzyme had a specific activity of 14--23 U, as measured by BAEE hydrolysis. Some properties of highly purified kallikrein are described.

Preparation and some properties of human serum kallikrein immobilized on ARM-Sepharose

A highly purified human serum kallikrein immobilized on CH-Sepharose 4-B was obtained. KM values for N-benzoyl-L-arginine ethyl ester and N-tosyl-L-arginine methyl ester hydrolysis of this preparation were 1.10 x 10(-3) M and 3.6 x 10(-4) M, respectively; pH optimum of hydrolysis of these esters were found to be 8.2 and 8.5, respectively. The immobilized kallikrein possessed kininogenase activity and was capable of activating prekallikrein.