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Enhancement of hematopoietic recovery in gamma-irradiated mice by the joint use of diclofenac, an inhibitor of prostaglandin production, and glucan, a macrophage activator.

The effects of diclofenac (inhibitor of prostaglandin production) and carboxymethylglucan (immunomodulator and an agent stimulating hematopoiesis), when given to mice 1 day before gamma-irradiation, were studied. Both of the agents were administered either alone or in combination. The investigations included the assessment of post-irradiation hematopoietic recovery in terms of bone marrow and spleen cellularity and endogenous spleen colony formation, as well as the determination of the survival of lethally irradiated mice. The results demonstrated at least additive radioprotective effects when mice were given diclofenac and carboxymethylglucan in combination. Experimental evidence provided by the increased 125iodo-deoxyuridine incorporation into the spleen and elevated hydroxyurea kill of endogenous spleen colony-forming units indicated that the beneficial action of the combined treatment could be a consequence of increased cell proliferation in the hematopoietic tissue. It is likely that the inhibition of prostaglandin production (diclofenac action) and the concomitant increased release of growth factors (glucan action) shift the regulatory balance towards the predominance of positive hematopoietic control.

Animals↗

[Myelodysplastic syndrome: experience of the Study and Treatment of Bone Marrow Failure Group].

Myelodysplastic syndromes (SMD) were studied in 58 patients (37 men, 21 women; mean age 61 years, range 18-81) who were grouped according to FAB criteria (Table 1). None of them showed a secondary SMD to medullary toxic agents or cytostatic treatments although 5 presented concomitant neoplastic disease. Morphologic alterations in peripheral blood smears and bone marrow were registered by 3 hematologists working independently. The intracellular and extracellular iron deposits were evaluated in every case with Perls; peroxidase activity was determined in 16 patients and intraleucocitary alkaline phosphatase reaction was carried out in 17 patients. Twenty five patients (43%) had refractory anemia (RA); 10 (17%) sideroblastic anemia; 13 (25%) refractory anemia with excess of blasts (AREB); 3 (5%) AREB in transformation (AREB-T) and 7 myelomonocytic leukemia (LMMC). Clinical manifestations at diagnosis are described in Table 2. In the observation period there were cases of anemia requiring transfusion, bacterial infections, muco-cutaneous hemorrhage and hemorrhagic episodes in the central nervous system. In the bone marrow smears the cellularity was normal or increased in 53 cases and diminished in only 3. The degree of dysplastic characteristics (erythroid, granulocytic and megakaryocytic) ranged from low to severe. It was low in most of AR, being the erythroid population the most affected in AS and the granulocytic one in AREB and AREB-T. Patients with LMMC showed similar characteristics to those with myeloproliferative syndromes and the differential diagnosis were sometimes difficult, accounting for their separate inclusion in Table 4. Out of 23 patients, 5 presented clonal pathology detected in cytogenetic studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

The 2001 World Health Organization and updated European clinical and pathological criteria for the diagnosis, classification, and staging of the Philadelphia chromosome-negative chronic myeloproliferative disorders.

The clinical criteria according to the Polycythemia Vera Study Group (PVSG) do not distinguish between essential thrombocythemia (ET), thrombocythemia associated with early-stage polycythemia vera (PV) and prefibrotic chronic idiopathic myelofibrosis (CIMF). The criteria only classify the advanced stage of PV with increased red cell mass. The classification of myeloproliferative disorders (MPDs), proposed by the World Health Organization (WHO) in 2001, is a compromise of the clinical PVSG and WHO bone marrow criteria, and excludes early stages of ET and PV. The updated European clinical and pathological criteria combine the WHO bone marrow criteria with established and new clinical, laboratory, biological, and molecular MPD markers. This allows clinicians and pathologists to diagnose early-stage MPD and to differentiate ET, PV, and prefibrotic chronic idiopathic myelofibrosis (CIMF). Depending on laboratory tests and diagnostic criteria used, the population of the MPD patients defined as ET, PV, and CIMF are heterogeneous at the clinical, laboratory, and biological and pathological levels. The recent discovery of the JAK2 V617F mutation, which is the cause of a distinct trilinear MPD in its manifold clinical manifestations during long-term follow-up, increases the specificity of a positive JAK2 V617F polymerase chain reaction (PCR) test for the diagnosis of MPD (near 100%), but only half of the ET and CIMF patients according to the PVSG (sensitivity 50%) and the majority of PV patients (sensitivity 95%) are JAK2 V617F positive. A comparison of the laboratory features of JAK2 V617-positive and JAK2 wild-type ET patients clearly showed that JAK2 V617-positive ET is characterized by higher values for hemoglobin, hematocrit, and neutrophil counts; lower values for serum erythropoietin (EPO) levels, serum ferritin, and mean corpuscular volume; and by increased cellularity of the bone marrow in biopsy material. This indicates that JAK2 V617-positive ET patients, diagnosed according to the PVSG criteria, represent a "forme fruste of PV" consistent with early PV mimicking ET (JAK2 V617F trilinear MPD). In contrast, the JAK2 wild-type ET patients had significantly higher platelet counts and usually had a clinical picture of ET with normal serum EPO levels, PRV-1 expression, and leukocyte alkaline phosphatase score, and a typical WHO ET bone marrow picture. The clinical and pathological data on JAK2 V617F-positive MPD patients suggest that the JAK2 V617F mutation defines one disease entity with several sequential steps of ET, PV, and secondary myelofibrosis during long-term follow-up, and that the wild-type JAK2 MPDs may represent another distinct entity with a related but different molecular etiology. MPD-specific markers such as serum EPO, endogenous erythroid colony formation (EEC), and JAK2 V617F have high specificities, but the sensitivities are not high enough to detect the early stages of the MPDs, ET, PV, and prefibrotic CIMF. Bone marrow histopathology in addition to clinical, laboratory, biological, and molecular markers, including the JAK2 V617 PCR test, serum EPO, PRV-1, EEC, LAP score, peripheral blood parameters, and spleen size on echogram will detect the early stages of MPD and allows diagnostic differentiation of the three primary MPDs (ET, PV, and CIMF) in both JAK2 V617F-positive and JAK2 wild-type MPD patients.

Biomarkers↗

Myelodysplastic syndromes: an analysis of clinical and haematological features.

A retrospective analysis of 24 cases of myelodysplastic syndromes was performed between 1979-1984. There were 16 men and 8 women with a mean age of 69 years and 65 years respectively. The most common haematological features at initial presentation were refractory macrocytic anaemia, reticulocytopenia and associated with either bicytopenia or pancytopenia. The bone marrow was often cellular with megaloblastoid erythropoiesis and in 7 patients (29%), there were ring sideroblasts. Often there was associated dysgranulopoiesis and dysthrombopoiesis Myelodysplastic syndromes appear morphologically to be a heterogenous entity. An attempt to classify them according to the recent proposal of the French-American-British (FAB) Co-operative Group was made. Transformation into acute non-lymphocytic leukaemia occurred in 6 patients (25%). The mean interval between diagnosis and transformation to acute leukaemia was 13 months (range 3-30 months). Acute leukaemia in these patients were refractory to conventional chemotherapy. There were 14 deaths (58%) observed during the period and the common causes of deaths were acute leukaemia, infections and haemorrhage. At present there is no specific or generally effective therapy for this haematologic entity.

Aged↗

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.

Animals↗

Isolation of a novel PDZ-containing myosin from hematopoietic supportive bone marrow stromal cell lines.

Stromal cells in bone marrow provide an optimal microenvironment for hematopoiesis. The established stromal cell lines from bone marrow showed various cellular heterogeneities and differed in their hematopoietic supportive ability. By a differential display method, we cloned a gene whose expression levels were correlated with the hematopoietic supportive ability of stromal cells. Its deduced amino acid sequence shows a structure similar to myosins, except that it lacks an actin binding site. Interestingly, it contains a KE-rich sequence and a PDZ domain in the NH(2)-terminal, which are protein-protein interaction domains; therefore we termed this novel myosin Myosin containing PDZ domain (MysPDZ). Western blot analysis showed that its protein levels positively correlated with the supportive ability of stromal cells and immunostaining suggested that MysPDZ was present at cytoskeleton in a filamentous and/or network form. Thus MysPDZ may be involved in the maintenance of the stromal cell architectures required for cell to cell contact.

Amino Acid Sequence↗

Pretransplant chemotherapy reduces inflammatory cytokine production and acute graft-versus-host disease after allogeneic bone marrow transplantation.

BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha) is known to be a critical effector molecule in the pathogenesis of graft-versus-host disease (GVHD), and elevated levels during bone marrow transplantation (BMT) conditioning are associated with more severe GVHD. Many patients receive chemotherapy prior to BMT, but its effect on subsequent toxicities is controversial. METHODS: We studied the effect of prior chemotherapy on GVHD severity and inflammatory cytokine generation in a well-established murine model of allogeneic BMT (B6-->B6D2F1). RESULTS: Three weeks after a single dose of cyclophosphamide, bone marrow and splenic cellularity was reduced by 50% and the production of TNF-alpha to LPS stimulation by macrophages was also markedly impaired (both before and after total body irradiation). Allogeneic BMT recipients previously treated with cyclophosphamide had significantly less GVHD and improved survival relative to recipients previously pretreated with diluent only. This survival advantage was associated with reduced systemic levels of both TNF-alpha and interleukin-1beta 7 days after BMT. This reduction occurred despite equivalent serum levels of lipopolysaccharide, consistent with the reductions in TNF-alpha and interleukin-1beta production by host macrophages after cyclophosphamide pretreatment. CONCLUSIONS: These data support the notion that patients entering BMT conditioning without prior cytotoxic treatment (e.g., patients with chronic myeloid leukemia) may be at increased risk of posttransplant complications associated with excessive inflammatory cytokine production.

Acute Disease↗

Myelostimulatory activity of recombinant human interleukin-2 in mice.

In a series of studies designed to extend our understanding of interleukin-2 (IL-2) and to study the effect of biologic response modifiers on bone marrow, we observed that administering recombinant human (rH) IL-2 to normal mice resulted in an increase in the frequency of colony-forming units-culture (CFU-C) in bone marrow. In addition, rH IL-2 was able to accelerate host recovery from cyclophosphamide (CTX)- or radiation-induced bone marrow depression and peripheral blood leukopenia. Not only can rH IL-2 accelerate, in a dose-dependent manner, the return of bone marrow, peripheral blood cellularity, and CFU-C frequency to normal levels following cytoreduction by CTX or irradiation, but it also significantly increases CFU-C frequency to greater than normal levels. Furthermore, rH IL-2 can significantly prolong survival of animals receiving a lethal dose of irradiation or CTX. Thus, multiple mechanisms are responsible for the synergistic therapeutic activity associated with rH IL-2 and CTX. rH IL-2 does not act only as an immunomodulatory agent in the presence or absence of suppressor T cells, but also accelerates host recovery from cytoreductive agents, resulting in decreased leukopenia and perhaps resistances to secondary infection. Thus, rH IL-2 plus chemotherapy may increase therapeutic activity against neoplastic disease, not only by adding immune stimulation to the direct antitumor effect of the drug but also by allowing delivery of higher, more effective doses of chemotherapy.

Animals↗

Toxicity of a quinocarmycin analog, DX-52-1, in rats and dogs in relation to clinical outcome.

PURPOSE: Quinocarmycin analog DX-52-1 is a cyanated derivative of quinocarmycin, a compound isolated from cultures of Streptomyces melanovinaceus. DX-52-1 was selected for preclinical development because it showed efficacy against melanoma cell lines in the NCI human tumor cell screen and melanoma xenografts in mice. This report describes studies in rats and dogs to determine the maximum tolerated dose (MTD) and identify dose-limiting toxicities (DLT) in each species in different regimens to establish a safe starting dose and potential target organs of DX-52-1 for phase I clinical trials. METHODS: DX-52-1 was administered to Fischer 344 rats using repeated intravenous (i.v.) slow bolus injections following q3hx3 and q3hx3,q7dx3 regimens, and to beagle dogs using a single injection, 6-h continuous i.v. infusion (c.i.v.) and weekly 6-h c.i.v. for 3 weeks. Endpoints evaluated included clinical observations, body weights, hematology, serum clinical chemistry, and microscopic pathology of tissues. RESULTS: The MTD of DX-52-1 was a total dose of 18 mg/m(2) body surface area for q3hx3 administration in rats and 30 mg/m(2) for a single c.i.v. administration in dogs. The total dose MTD for rats on a weekly (q3hx3,q7dx3) regimen was 54 mg/m(2), and for dogs on the weekly x3 (6-h c.i.v.) infusion was 60 mg/m(2). In rats, significant elevations in blood urea nitrogen and creatinine were observed together with acute renal tubular necrosis histologically. Modest increases in liver enzymes were also observed, as were decreases in reticulocytes that were unaccompanied by histologic changes in liver and bone marrow. In dogs, adverse signs included vomiting/retching, diarrhea, and transient hypothermia; also red blood cells, hemoglobin, hematocrit, and lymphocytes were decreased. Histologic evaluation of tissues from dogs revealed necrosis and cellular depletion of the bone marrow, and extensive damage to the entire gastrointestinal tract, including marked cellular necrosis of the mucosa and lymphoid necrosis of the gastrointestinal associated lymphoid tissue. Destruction of the mucosal lining of the intestinal tract was likely responsible for dehydration, toxemia, septicemia, and shock seen in moribund dogs. CONCLUSIONS: The MTD values were comparable between rats and dogs given roughly similar dose regimens (single dose or weekly) and both species tolerated a higher total dose with weekly administration. However, the principal target organ responsible for DLT in rats was the kidney, whereas in dogs, the most severe effects were on the gastrointestinal tract and bone marrow. Both renal and gastrointestinal toxicities were reported in patients after 6-h c.i.v. infusions in a limited phase I clinical trial, indicating that neither animal model alone was predictive of DX-52-1-induced toxicity in humans, and that both species were required to define human toxicity.

Animals↗

Single administration of thrombopoietin to lethally irradiated mice prevents infectious and thrombotic events leading to mortality.

A sufficiently high dose of thrombopoietin to overcome initial c-mpl-mediated clearance stimulates hematopoietic reconstitution following myelosuppressive treatment. We studied the efficacy of thrombopoietin on survival after supralethal total body irradiation (9 Gy) of C57BL6/J mice and the occurrence of infectious and thrombotic complications in comparison with a bone marrow graft or prophylactic antibiotic treatment. Administration of 0.3 microg thrombopoietin, 2 hours after irradiation, protected 62% of the mice as opposed to no survival in placebo controls. A graft with a supraoptimal number of syngeneic bone marrow cells (10(6) cells) fully prevented mortality, whereas antibiotic treatment was ineffective. Blood cell recovery was observed in the thrombopoietin-treated mice but not in the placebo or antibiotic-treated group. Bone marrow and spleen cellularity as well as colony-forming unit granulocyte-macrophage and burst-forming unit erythroid were considerably increased in thrombopoietin-treated mice relative to controls. Histologic examination at day 11 revealed numerous petechiae and vascular obstructions within the brain microvasculature of placebo-treated mice, which was correlated with hypercoagulation and hypofibrinolysis. Thrombopoietin treatment prevented coagulation/fibrinolysis disorder and vascular thrombosis. High fibrinogen levels were related to bacterial infections in 67% of placebo-treated mice and predicted mortality, whereas the majority of the thrombopoietin-treated mice did not show high fibrinogen levels and endotoxin was not detectable in plasma. We conclude that thrombopoietin administration prevents mortality in mice subjected to 9-Gy total body irradiation both by interfering in the cascade leading to thrombotic complications and by amelioration of neutrophil and platelet recovery and thus protects against infections and hemorrhages.

Animals↗

Growth of normal and malignant bone marrow cells.

Results of five different methods (heme breakdown, mitotic indices, total marrow cellularity and different methods of labelling indices) to determine bone marrow cell growth are reviewed. Normal immature erythroblasts and myeloblasts have generation times of about 5-10 h. Erythroblasts in neoplastic conditions (the myelodysplastic syndrome and polycythemia vera) have generation times which are significantly prolonged, by 12-75 per cent, but this may not be true for myeloblasts, since total labelling indices are increased (from normal 3.9 to 11.2 per cent) in the myelodysplastic syndrome. In contrast, generation times in aplastic anemia are significantly shortened, by about 70-80 per cent. Normal mature erythroblasts and promyelocytes have generation times of about 24 h, and the malignant prolongation may be even greater.

Anemia, Aplastic↗

Establishment, characterization and determination of cell surface sugar receptor (lectin) expression by neoglycoenzymes of a human myeloid marker-expressing B lymphoblastoid cell line.

Mediation of cellular interactions by protein (lectin)-carbohydrate recognition presupposes the expression of respective surface determinants. Due to the importance of cellular contacts between bone marrow stromal cells, recently shown to express cell surface lectins, and tumor or normal progenitor cells for biosignaling and marrow egress, quantitation of cell surface sugar receptor expression by a panel of chemically glycosylated enzymes (tetrameric E. coli beta-galactosidase) for human leukemia/lymphoma cells was initiated. Cells of the new B lymphoblastoid line Croco II that are partially positive for the CD15-specific epitope expressed receptors for various sugar specificities on their surface, fulfilling an indispensable prerequisite for establishment of glycobiological interactions. Binding studies with increasing neoglycoenzyme concentrations up to saturation in four cases disclosed values for apparent affinity constants in the range of 25-200 nM with 0.25-3 x 10(5) bound probes per cell. The presence of receptors for constituents of carbohydrate chains of cellular glycoconjugates was also ascertained biochemically, namely for beta-galactosides, alpha-mannosides, alpha-fucosides and N-acetylgalactosaminides. Expression of this property was modulated by changes in the culture conditions, as revealed by binding studies with cells, derived from growth in medium containing different serum concentrations. These findings indicate that cell surface sugar receptors of tumor cells warrant further attention with respect to recognitive interactions.

Antigens, CD↗

Loss of tolerance and autoimmunity affecting multiple organs in STAT5A/5B-deficient mice.

STAT5 has previously been reported to be dispensable for the maintenance of tolerance in vivo. However, in examining hemopoiesis in mice lacking both isoforms of STAT5, STAT5A, and STAT5B, we noted that a subset of these mice demonstrated dramatic alterations in several bone marrow progenitor populations concomitant with lymphocytic infiltration of the bone marrow. In addition, cellular infiltration affecting the colon, liver, and kidney was observed in these mice. Survival analysis revealed that STAT5A/5B(-/-) mice exhibited early death. The increased mortality and the pathology affecting multiple organs observed in these mice were abrogated on the recombination-activating gene 1(-/-) background. In light of the similarities between STAT5A/5B-deficient mice and mice unable to signal through the IL-2R, we hypothesized that the tolerizing role of STAT5A/5B was triggered via activation of the IL-2R. In agreement with this, we found that IL-2Rbeta chain-deficient mice exhibited similar hemopoietic abnormalities. Because IL-2 signaling is thought to contribute to tolerance through maintenance of a CD4(+)CD25(+) regulatory T cell population, we examined these cells and observed a numerical reduction in STAT5A/5B(-/-) mice along with a higher rate of apoptosis. These data provide strong evidence for a requirement for STAT5 in the maintenance of tolerance in vivo.

Adoptive Transfer↗

Characterization of cells with high alkaline phosphatase activity derived from human bone and marrow: preliminary assessment of their osteogenicity.

Confluent cellular layers are reproducibly obtained (from 21 of 24 specimens) by outgrowth from composite pieces of human trabecular bone and marrow. The cells resemble fibroblasts in terms of morphology, esterase profile, and production of collagen type 1. However, the cells displayed some osteoblastlike features. Both the primary outgrowths and passaged cultures had high alkaline phosphatase activities (37 nmols min-1 X microgram DNA-1) in the range displayed by embryonic osteoblastlike cells. The cellular alkaline phosphatase activity, which showed similarity to the bone isoenzyme on kinetic criteria, was stimulated by 1,25-dihydroxyvitamin D3 but decreased by PTH (1-34). In addition, the cell preparations were shown to increase osteocalcin (bone Gla protein) production in response to 1,25-dihydroxyvitamin D3. The osteogenic potential of the bone and marrow-derived cells has been assessed in an in vivo diffusion chamber assay in which congenitally athymic (nude) mice were used as hosts. None of the 25 chambers examined showed evidence of osteogenesis, although the cells remained viable and fibroblastlike. The alkaline phosphatase activities decreased to less than 1% of the original, high in vitro values. The findings question the hypothesis that bone and marrow-derived cells are osteoblasts or osteoblastlike cells, rather than a mixture of cell lines of the bone and marrow stromal system.

Adolescent↗

Congenital dyserythropoietic anaemia with features of both type I and TYPE II.

A 13 year old girl with the typical clinical and haematological picture of congenital dyserythropoietic anaemia (CDA) is reported. The bone marrow is highly cellular with 70 per cent erythroid cells, and 28% bi- and multinuclear cells among the orthochromatic and polychromatic erythroblasts. Moderate megaloblastoid changes are present. On light microscopy the findings are in agreement with those described in CDA type II. On electron microscopy both the cytoplasmatic changes described as typical of CDA type II, and the nuclear changes found in type I can be demonstrated. The acidified serum test (Ham test) is negative with normal sera. The patient's red blood cells show increased agglutinability with anti-I and and anti-I antibodies, but no haemolysis. Total serum lipids are about 50% of the normal average. All lipoprotein classes are lowered to about the same extent. The total phospholipid content of the erythrocytes is slightly reduced, with a moderate, relative increase of the lecithin fraction and a decrease of the sphingomyelin fraction. Doubts can be raised about the tenability of the current classification of CDA based on morphological and serological criteria, especially about the distinction between types I and II.

Adolescent↗

Bone marrow hyaluronan distribution in patients with acute myeloid leukemia.

Acute myeloid leukemia (AML) is a clonal disorder characterized by abnormal proliferation of myeloid cell precursors. Research has mainly focused on the cellular events, but the bone marrow matrix has attracted minor interest. In this study bone marrow biopsies were obtained from 35 newly diagnosed AML patients. The bone marrows were analyzed regarding the occurrence and distribution of hyaluronan (HYA) and reticulin fibers (type III collagen). The bone marrow sections were analyzed histochemically and compared with bone marrows from 30 healthy controls. The HYA staining was significantly stronger in the AML patients compared with the controls. Only one patient demonstrated abnormal reticulin staining score, but in the group of patients with antecedent myelodysplastic syndrome (MDS), the reticulin staining score was significantly higher compared with the patients with de novo AML. There was a significant correlation between the HYA staining and reticulin staining scores in the AML patients as was seen in the control group.

Adult↗

The primary and secondary cellular immune responses to whole cell Bordetella pertussis vaccine and its components.

The cellular immune responses of Balb/c mice and Wistar rats immunized in hind footpads with intact killed Bordetella pertussis were found to differ from those of similar animals immunized with other bacteria including Bordetella bronchiseptica, Salmonella typhimurium and Escherichia coli. All the bacteria stimulated increases in cell number, proliferation and interleukin 2 (IL-2) production in popliteal lymph nodes which peaked 3-5 days after injection and decreased to resting levels by day 7. However, B. pertussis also caused a second peak in all three parameters at 11 days after immunization. This peak was not seen following injection with any of the other bacteria. Bordetella pertussis also caused systemic effects, increased cellular proliferation in bone marrow and thymus, with similar biphasic kinetics. It possesses a potent toxin, distinguishing it from the closely related B. bronchiseptica. The use of purified materials confirmed that the presence of this pertussis toxin (PT) was responsible for the later peak in stimulation, whereas lipopolysaccharide (LPS) in combination with PT and also the filamentous haemagglutinin (FHA) could mimic the early peak of stimulation. Primary immunization with B. pertussis was also shown to generate lymph node cells which responded in vitro to secondary challenge with B. pertussis cells, FHA or PT. Both proliferation and IL-2 production were enhanced, except with FHA which only increased IL-2 production. Lymph node cells from mice immunized with E. coli showed no such responses.

Animals↗

Possible induction of graft-versus-leukemia effect against a leukemia refractory to antileukemia response in ordinary MHC-compatible, allogeneic bone marrow transplantation.

We previously indicated that intensity of the graft-versus-leukemia (GVL) effect varied among different leukemias in MHC-compatible, allogeneic bone marrow transplantation (BMT). Cellular factors responsible for differences in intensity of the GVL effect were examined by using two types of leukemias, i.e., a resistant leukemia (LE750) and a sensitive leukemia (8313) to induction of the GVL effect in MHC-compatible, allogeneic BMT of leukemia-bearing host. Resistance of LE750 leukemic cells to induction of the GVL effect could not be attributed to either less sensitivity to lysis by minor H antigen-specific, cytotoxic T cells or to an immunosuppressive activity of LE750 leukemic cells in leukemia-bearing host, when compared with the case of the sensitive leukemia (8313). To investigate the significance of the dose effect of effector cells for induction of the GVL effect, we used CD8+ T cells of AKR donor mice, which were shown to preferentially induce the GVL effect with hardly any lethal graft-versus host disease against C3H recipient mice, enabling us to increase the number of CD8+ T cells used in the allogeneic donor inoculum. The results suggested that the outcome of the antileukemic response in allogeneic BMT of leukemic recipients may be determined, at least in part, by the balance between the size of leukemic cells surviving and repopulating in the recipients after BMT and the number of antileukemic effector cells. The results furthermore indicated that when donors with T-cell subsets that preferentially induce an antileukemic response with reduced graft-versus-host disease are available, a more effective antileukemic response is inducible even against advanced leukemias.

Animals↗