Japanese Subgroup Analyses from EMERGE and ENGAGE, Phase 3 Clinical Trials of Aducanumab in Patients with Early Alzheimer's Disease.

BACKGROUND: Global prevalence and incidence of dementia continue to rise at a rapid rate. There is a need for new Alzheimer's disease (AD) treatments globally. Aducanumab is a human monoclonal antibody that selectively targets aggregated soluble amyloid beta oligomers and insoluble amyloid beta fibrils. In June 2021, aducanumab was approved by the US Food and Drug Administration for the treatment of AD under the accelerated approval pathway. OBJECTIVES: We evaluated the efficacy, safety, biomarker and pharmacokinetics (PK) of aducanumab in Japanese subgroups in EMERGE and ENGAGE studies. DESIGN: EMERGE and ENGAGE were two randomized, double-blind, placebo-controlled, global, phase 3 studies of aducanumab in patients with early AD (mild cognitive impairment due to AD or mild AD dementia). SETTING: These studies involved 348 sites in 20 countries. PARTICIPANTS: Participants enrolled in Japan included 121 (7.4% of total 1638 in EMERGE) and 100 (6.1% of total 1647 in ENGAGE) patients (aged 50-85 years with confirmed amyloid pathology) who met clinical criteria for mild cognitive impairment due to AD or mild AD dementia. INTERVENTION: Participants were randomly assigned 1:1:1 to receive aducanumab low dose (3 or 6 mg/kg target dose), high dose (6 or 10 mg/kg target dose) or placebo via IV infusion once every 4 weeks over 76 weeks. MEASUREMENTS: The primary outcome measure was change from baseline to Week 78 on the Clinical Dementia Rating Sum of Boxes (CDR-SB), an integrated scale that assesses both function and cognition. Other measures included safety assessments; secondary and tertiary clinical outcomes that assessed cognition, function, and behavior; biomarker endpoints (amyloid PET and plasma p-tau181); serum PK profiles and immunogenicity. RESULTS: Results from the Japanese subgroup analyses were generally consistent with those of the overall study population across endpoints, while a lower mean body weight (kg) and a smaller proportion of ApoE ε4 carriers were observed in the Japanese subgroup population. A treatment effect was observed in favor of aducanumab on the primary and secondary efficacy endpoints at Week 78 in EMERGE, but not ENGAGE. The incidence and type of adverse events in the Japanese subgroups were generally comparable to those observed in the overall study population; amyloid related imaging abnormalities (ARIA) were common treatment-related adverse events that appeared to be related to the aducanumab dose. ARIA incidence was generally lower in the Japanese subgroup compared with the overall population. Consistent with the overall data set, a robust dose-dependent decrease in amyloid beta levels as assessed with amyloid-PET and plasma p-tau181 was observed. Serum PK profiles and immunogenicity of aducanumab in Japanese population were consistent with the non-Japanese population. CONCLUSION: Efficacy, safety, biomarker, and PK profiles of aducanumab were consistent between the Japanese subgroup and the overall population. A positive treatment effect of aducanumab on efficacy endpoints was observed in EMERGE, but not in ENGAGE.

Organ-specific autoimmune diseases induced in mice by elimination of T cell subset. I. Evidence for the active participation of T cells in natural self-tolerance; deficit of a T cell subset as a possible cause of autoimmune disease.

Organ-specific autoimmune diseases such as oophoritis, gastritis, thyroiditis, and orchitis were induced in female or male nude (nu/nu) mice by the transfer of nu/+spleen cells from which particular Lyt T cell subset(s) had been removed: nu/+spleen cells treated with anti-Lyt-1 plus complement (C) caused disease in recipient nude mice; anti-Lyt-2 plus C-treated spleen cells, in contrast, did not. The cells responsible for disease induction are believed to be Thy-1+, Lyt-1-, 2,3- (Thy-1, Lyt-1, 2,3), since spleen cells treated with mixed antisera, including anti-Lyt-1 and anti-Lyt-2, plus C, could induce the disease with almost the same incidence as anti-Lyt-1 plus C-treated cells (oophoritis 50%, gastritis 25%, thyroiditis 10-20%, and orchitis 40%). Cells treated with mixed antisera of anti-Thy-1, anti-Lyt-1, and anti-Lyt-2, plus C, could not induce autoimmune disease. Each induced autoimmune disease could be adoptively transferred to other nude mice via spleen cells, with resulting histological lesion of corresponding organs and development of specific circulating autoantibodies. Since anti-Thy-1 plus C treatment of donor spleen cells abrogated the capacity to transfer the disease, we conclude that T cells are required as effector cells, and that these may develop from Lyt-1-, 2,3- cells. Lyt-1+, 2,3- cells were demonstrated to have suppressive activity upon the development of the diseases; induction of autoimmunity was completely inhibited by the cotransfer of Lyt-1+, 2,3- cells with Lyt-1-, 2,3- cells. When anti-Lyt-2 plus C-treated cells (i.e., Lyt-1+, 2,3- and Lyt-1-, 2,3- cells) were mixed with anti-Lyt-1 and anti-Lyt-2 plus C-treated cells (i.e., Lyt-1-, 2,3- cells) in various ratios, then transferred to nude mice, the development of each autoimmune disease was clearly inhibited, even by small doses of Lyt-1+, 2,3- cells. The autoimmune disease we were able to induce was quite similar to human organ-specific autoimmune disease in terms of the spectrum of organs involved, histopathological features, and the development of autoantibodies to corresponding organ components (oocytes, parietal cells, thyroid colloid, including thyroglobulin, and sperm).(ABSTRACT TRUNCATED AT 400 WORDS)

The absence of interleukin 1 receptor-related T1/ST2 does not affect T helper cell type 2 development and its effector function.

T1/ST2, an orphan receptor with homology with the interleukin (IL)-1 receptor family, is expressed constitutively and stably on the surface of T helper type 2 (Th2) cells, but not on Th1 cells. T1/ST2 is also expressed on mast cells, which are critical for Th2-mediated effector responses. To evaluate whether T1/ST2 is required for Th2 responses and mast cell function, we have generated T1/ST2-deficient (T1/ST2(-/-)) mice and examined the roles of T1/ST2. Naive CD4(+) T cells isolated from T1/ST2(-/-) mice developed to Th2 cells in response to IL-4 in vitro. T1/ST2(-/-) mice showed normal Th2 responses after infection with the helminthic parasite Nippostrongylus brasiliensis as well as in the mouse model of allergen-induced airway inflammation. In addition, differentiation and function of bone marrow-derived cultured mast cells were unaffected. These findings demonstrate that T1/ST2 does not play an essential role in development and function of Th2 cells and mast cells.

A novel clinical role for angiopoietin-1 in malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is an aggressive malignant tumour associated with asbestos exposure that has only a limited response to conventional therapy; therefore, diagnosing MPM early is very important. We have previously reported that angiopoietin (Ang)-1 was correlated with bleomycin-induced pulmonary fibrosis. Here, we investigated the association of Ang-1 with the development of MPM cells, which originate from mesenchymal cells similar to lung fibroblasts, and demonstrated that Ang-1 stimulated the growth and migration of MPM cells in vitro. We also demonstrated that patients with MPM had significantly higher serum levels of Ang-1 in comparison to a population who had been exposed to asbestos but had not developed MPM. The patients with advanced-stage MPM showed higher levels of Ang-1 than the early-stage MPM patients and the Kaplan-Meier method revealed a significant correlation between serum Ang-1 levels and survival. We propose the possibility that Ang-1 plays an important role in MPM tumour growth and our data suggest that the serum concentration of Ang-1 could be useful as prognostic factor.

All-trans-retinoic acid inhibits tumour growth of malignant pleural mesothelioma in mice.

Malignant pleural mesothelioma (MPM) is an aggressive malignant tumour of mesothelial origin associated with asbestos exposure. Because MPM has limited response to conventional chemotherapy and radiotherapy, the prognosis is very poor. Several researchers have reported that cytokines such as interleukin (IL)-6 play an important role in the growth of MPM. Previously, it was reported that all-trans-retinoic acid (ATRA) inhibited the production and function of IL-6 and transforming growth factor (TGF)-beta1 in experiments using lung fibroblasts. We investigated whether ATRA had an inhibitory effect on the cell growth of MPM, the origin of which was mesenchymal cells similar to lung fibroblasts, using a subcutaneous xenograft mouse model. We estimated the tumour growth and performed quantitative measurements of IL-6, TGF-beta1 and platelet-derived growth factor (PDGF) receptor (PDGFR)-beta mRNA levels both of cultured MPM cells and cells grown in mice with or without the administration of ATRA. ATRA significantly inhibited MPM tumour growth. In vitro studies disclosed that the administration of ATRA reduced 1) mRNA levels of TGF-beta1, TGF-beta1 receptors and PDGFR-beta, and 2) TGF-beta1-dependent proliferation and PDGF-BB-dependent migration of MPM cells. These data may provide a rationale to explore the clinical use of ATRA for the treatment of MPM.

Expression of the T cell receptor Vbeta repertoire in a human T cell resistant to asbestos-induced apoptosis and peripheral blood T cells from patients with silica and asbestos-related diseases.

To explore the effects of asbestos and silica on the human immune system, an experimental model of low-dose and long-term exposure was established using a human HTLV-1-immortalized polyclonal T cell line, MT-2 (MT-2Org). MT-2 cells were continuously exposed to asbestos at a concentration (10 microg/ml) which does not induce complete cell death during short-term exposure. After acquiring resistance to CB-induced apoptosis (designated MT-2Rst), an immunological comparison was made between the MT-2Org and MT-2Rst lines in terms of T cell receptor-Vbeta (TcR-Vbeta) expression. MT-2Rst cells showed excess expression of various TcR-Vbeta, although TcR-Vbeta-overpresenting cells were characterized as undergoing apoptosis due to first contact with CB. Patients with asbestos-related diseases (ARD), such as asbestosis and malignant mesothelioma, were compared with silicosis (SIL) patients as a disease control and with healthy donors (HD). SIL and ARD not only differed in their causative materials, silica and asbestos as mineral silicates, but also in terms of complications; autoimmune disorders in SIL and tumors in ARD. ARD patients showed a restricted overpresentation of TcR-Vbeta without clonal expansion, whereas SIL patients revealed significant overpresentation of TcR-Vbeta 7.2. These experimental and clinical analyses indicate the superantigenic and dysregulation of autoimmunity-inducing effects of asbestos and silica, respectively.

Establishment and characterization of a tumorigenic murine vascular endothelial cell line (F-2).

A new murine cell line, designated F-2, was established from an ultraviolet light-induced tumor which developed on the back skin of a BALB/c x C57BL/6 F1-nu/nu nude mouse. More than 1 x 10(5) F-2 cells injected into nude mouse skin produced rapidly developing hemangiomatous lesions. F-2 had a 14-h doubling time under 10% fetal calf serum-containing Dulbecco's modified Eagle's medium culture conditions without any cell growth factor supplementation, and it showed "cobblestone" appearance at confluency. F-2 was able to rapidly differentiate on Matrigel with resultant fine network structure and tubule formation. Ultrastructural observations of the tubule demonstrated that the F-2 cells were connected to each other by intermediate junctions and arranged to form spaces, but that no Weibel-Palade bodies were found in the cytoplasm. F-2 also showed the active uptake of fluorescent-labeled acetylated low-density lipoprotein at 37 degrees C but not at 4 degrees C, and it showed prominent binding to the lectin, Griffonia simplicifolia I agglutinin. The addition of fibroblast growth factor did not facilitate the growth of F-2 cells. These findings strongly suggest that F-2 is a transformed cell line with tumorigenicity and vascular endothelial cell properties, and it may be useful in the study of vascular tumor biology.

A novel hydrophobized polysaccharide/oncoprotein complex vaccine induces in vitro and in vivo cellular and humoral immune responses against HER2-expressing murine sarcomas.

To elicit specific cellular immune responses against cancer, the development of efficient devices to deliver tumor antigen peptides to the MHC class I pathway constitutes a central issue. We report here a novel formula of hydrophobized polysaccharide nanoparticles, which can deliver a HER2 oncoprotein containing an epitope peptide to the MHC class I pathway. A protein consisting of the 147 amino-terminal amino acids of oncogene erbB-2/neu/HER2 (HER2) was complexed with two kinds of hydrophobized polysaccharides, cholesteryl group-bearing mannan (CHM) and cholesteryl group-bearing pullulan (CHP), to form nanoparticles (CHM-HER2 and CHP-HER2). CHM-HER2 and CHP-HER2 were able to induce CD3+/CD8+ CTLs against HER2-transfected syngeneic fibrosarcoma cell lines. In contrast, the oncoprotein alone failed to do so. These CTLs were Kd-restricted and specifically recognized a peptide (position 63-71) that was a part of a truncated HER2 protein used as an immunogen. In addition, vaccination by CHM-HER2 complexes led to a strongly enhanced production of IgG antibodies against HER2, whereas vaccination with HER2 proteins alone resulted in a production of antibodies at a marginal level. Mice immunized with CHM-HER2 or CHP-HER2 before tumor challenge successfully rejected HER2-transfected tumors. The complete rejection of tumors also occurred when CHM-HER2 was applied not later than 3 days after tumor implantation. In the effector phase of in vivo tumor rejection, CD8+ T cells played a major role. The results suggest that a sort of hydrophobized polysaccharide may help soluble proteins to induce cellular immunity as well enhance humoral immunity; hence, such a novel vaccine may be of potential benefit to cancer prevention and cancer therapy.

Animal model of silent myocarditis in athymic mice.

To clarify the role of the immune system in the development of myocarditis, BALB/c-nu/nu mice (group 1), BALB/c-nu/+ mice (group 2), BALB/c-nu/nu mice injected with 5 X 10(7) spleen cells from BALB/c-nu/+ mice (group 3), and BALB/c-nu/nu mice injected with 5 X 10(7) spleen cells from BALB/c-nu/+ mice treated with rat anti-Thy-1.2 monoclonal antibody with complement (group 4) were inoculated with encephalomyocarditis virus. There were no significant differences in the incidence of myocarditis among the four groups. Virus titrations of the heart and serum neutralising antibody titres in the four groups did not show any significant differences. Fifty two per cent (26/50) of group 2 and 43% (20/46) of group 3 died on days 9-15, when congestive heart failure developed. Only 9% (5/54) of group 1 and 8% (1/12) of group 4, however, died on days 9-15. Pathological examination confirmed congestive heart failure in groups 2 and 3 but not in groups 1 and 4. Dilatation of the ventricular cavities, pleural effusion, ascites, and congestion of the lungs and liver were present in groups 2 and 3 but not in groups 1 and 4. Cellular infiltration and myocardial necrosis were severe in groups 2 and 3 but minimal in groups 1 and 4. Thus the severity of myocarditis may be regulated by T cells. So-called silent myocarditis seen in clinical settings may be similar to myocarditis in BALB/c-nu/nu mice.

Comparative study of regional cerebral blood flow values measured by Xe CT and Xe SPECT.

The regional cerebral blood flow (rBCF) values measured by stable xenon-enhanced computed tomography (Xe XT) and by radioactive xenon-133 single photon emission computed tomography (Xe SPECT) were compared in 16 patients with cerebral infarct. On the non-lesion side Xe SPECT recorded 10.7% higher rCBF values than Xe CT in the anterior cerebral artery territory, while Xe CT recorded 9.6% higher values than Xe SPECT in the middle cerebral artery territory. These differences were not statistically significant. Although the rCBF values were almost the same, no correlation was found between the two methods in the posterior cerebral artery territory and the basal ganglia. Only hemispheric CBF on the non-lesion side showed the same value and a good correlation between the Xe CT and the Xe SPECT. There was a good correlation in the hemispheric CBF values on the lesion side, too. The difference of rCBF between the non-lesion side and the lesion side was expressed smaller in the Xe SPECT than in the Xe CT. This is in agreement with the previous reports that Xe SPECT overestimates the flow in the low flow areas. The higher rCBF values in the anterior cerebral artery territory measured by the Xe SPECT was ascribed to the artifact from the radioactivities in the inhalation mask and the air passages as reported previously. In conclusion, there is no good correlation between the rCBF values measured by the Xe CT and by the Xe SPECT. Only hemispheric CBF shows a good correlation between the two methods.

Enhanced inhibition of experimental metastasis by the combination chemotherapy of Cu-Zn SOD and adriamycin.

We previously reported that reactive oxygen species (ROS) enhance tumor cell metastasis, and by administration of recombinant human superoxide dismutase (rh SOD), an enzyme which scavenges O2- successfully reduced lung metastasis of mouse MethA sarcoma and Lewis lung carcinoma. These observations suggested that rh SOD suppressed tumor cell invasion by eliminating O2- the primary source of ROS. However, for the clinical application of the drug as an anti metastatic agent, rh SOD needs to be administered in combination with other cytotoxic agents, since SOD by itself has no cytotoxic activity. In this paper, we investigated the effectiveness of the combination chemotherapy of rh SOD and adriamycin (ADR), an anti-cancer agent against the experimental metastasis of highly metastatic clone, MH-02, which was derived from murine Meth A sarcoma. The present metastasis experiment clearly indicates that the administration of rh SOD enhances the antimetastatic effect of ADR. On the other hand, we found that the inhibition rate of metastasis exhibited by the combination chemotherapy of rh SOD and a certain dose (5 mg/ml) of ADR was inferior to that of rh SOD. This apparent paradoxical phenomenon was presumably explained by our finding that tumor cells themselves augment their invasive capacity and platelet aggregation, both of which are causative factors for metastasis formation, by generation of O2- when they were treated with ADR. Nevertheless, the combination chemotherapy of SOD with anticancer drugs such as ADR can be a practical anti-metastasis strategy.

Sandwich radioimmunolabeling for the study of surface properties of bone marrow lymphocytes.

A modification of sandwich radioautographic method was applied to the study of surface immunoglobulin and/or specific antigens on small lymphocytes in mouse and human bone marrow. After incubation of marrow cell suspensions at 37 degrees C, cells were reacted at 0 degree C for 30 min with graded dilutions of rabbit anti-mouse or anti-human immunoglobulin followed by further reaction with a sheep anti-rabbit immunoglobulin labeled with 125I. Detectable surface immunoglobulin was demonstrated in approximately one-third of mouse marrow lymphocytes and 20-25% of human marrow lymphocytes. The densities of surface immunoglobulin as assessed by grain counts on individual labeled lymphocytes tended to be lower in the marrow than in spleen or peripheral blood. When the same rabbit antiserum was used to compared the sensitivity of the sandwich method with that of the direct radioautography, the former was found sufficiently sensitive to give a plateau level of labeling without seriously increasing background grains. The advantages of the method are discussed with reference to studies on T and B cells specific antigens on human bone marrow lymphocytes.

Survival-promoting activity of IL-7 on IL-2-dependent cytotoxic T lymphocyte clones: resultant induction of G1 arrest.

Interleukin-7 (IL-7) is essential for both T cell and B cell development. Recent studies have suggested that IL-7 also functions as a survival-promoting factor for resting and activated T cells. In this study we examined the effects of IL-7 on survival and cytotoxicity of tumor-specific CD8(+) cytotoxic T lymphocyte (CTL) clones established and maintained either with IL-2 alone or with a combination of IL-2 and IL-7. While the CTL clones cultured in IL-2 alone died around day 10, the CTL clones cultured in the presence of IL-2 and IL-7 survived for more than 4 weeks after seeding. The long-term survival of the latter was correlated with the presence of IL-7 in the medium. In addition, IL-7 alone prolonged survival of other IL-2-dependent CTL clones after the removal of IL-2. IL-7 maintained the CTLs in G1 arrest after a slight proliferation during the initial phase during which low-level but sustained DNA synthesis was observed. However, there was no direct correlation between DNA synthesis and enhancement of long-term survival by IL-7 as demonstrated by the inhibiting proliferation of the CTL clones with the protein kinase inhibitor genistein. During long-term survival in the presence of IL-7, the cytotoxic activities of the CTL clones decreased gradually to background levels although they were restored soon after the next passage. These results suggested that IL-7 had the ability to set machinery in motion against apoptosis in the IL-2-dependent CTL clones. Such an effect of IL-7 might play a role in vivo in the process leading activated T cells to the resting, that is, memory state.

Lethal graft-versus-host disease in nude mice. I. Establishment of model systems.

We examined whether nude mice, which are deficient in T cell function, could be used as a model for induction of lethal graft-versus-host disease. Nude mice injected with MHC-disparate spleen cells exhibited only transient GVH reaction such as splenomegaly. Inoculation of B6 spleen cells into BALB/c nude mice produced high titers of alloantibodies to the donor cells. These alloantibodies eliminated host-MHC-reactive donor T cells from the host. After abolition by 400 rads irradiation of the capacity of nude mice to produce antibody, lethal GVHD could be induced by allogeneic spleen cell transfer and was mediated by donor T cells. This lethal GVHD was prevented by prior administration of antidonor alloantibody to the irradiated recipients at least 24 hr before donor-cell grafting. The role of alloantibody was substantiated in 2 other combinations in which little or no alloantibodies to donor spleen cells were produced. Engraftment of either MHC-identical but non-MHC disparate donor spleen cells into BALB/c nude mice or of parental spleen cells into F1 nude mice resulted in death mediated by T cells. In addition, irradiated BALB/c nude mice inoculated with non-MHC-incompatible B10.D2 spleen cells were much more sensitive to alloaggression by the donor cells than were nonirradiated hosts, indicating the presence of some radiation-sensitive component(s) acting in nude mice against GVHD induction by donor T cells. Thus the nude mouse is considered to be a useful recipient for clarifying the basic mechanisms involved in lethal GVHD.

The role of CD4+ and CD8+ cells in normal F1 hybrid host in the resistance to lethal graft-versus-host disease induction by transfer of parent spleen cells.

Transfer of a certain number of C57BL/6 (B6) spleen cells into (BALB/cxB6)F1 (CB6F1) nu/nu mice, which are deficient in T cells, causes lethal graft-versus-host disease (GVHD) in the recipients. However, when normal CB6F1 mice are used as recipients, lethal GVHD does not occur. Using this lethal GVHD system, we investigated which roles CD4+ and CD8+ T cells play in the resistance to lethal GVHD induction by parent cell transfer in the normal F1 hybrid host. Lethal GVHD induction by B6 spleen cells in CB6F1 nu/nu mice was blocked by prior reconstitution of the recipients with normal syngeneic spleen cells. In addition, all nu/nu mice reconstituted with syngeneic CD8+ spleen cells developed lethal GVHD, whereas none of the nu/nu mice reconstituted with CD4+ cells did. Both spleen weight and number of spleen cells in the former prominently decreased in contrast to the slight increase (peak at 15 weeks) seen in the latter after transfer of donor spleen cells. H-2Dd- Thy1.2+ cells, which are considered to derive from donor B6 T cells, existed in the spleen from the CD4+ spleen cell-reconstituted GVHD mice, peaking at 5 weeks then gradually decreasing after transfer of donor cells. However, they disappeared in the normal spleen cell-reconstituted GVHD mice 5 weeks later. These findings suggest that CD4+ cells in the normal F1 hybrid host play a critical role in the resistance to lethal GVHD induction by parent spleen cell transfer, although CD8+ cells are required for the prompt elimination of donor cells.

Overlapping epitopes of friend murine leukemia virus gag-encoded leader sequence recognized by single cytotoxic T-lymphocyte clones.

The leader signal sequence of the non-structural gag-encoded glycoprotein precursor, Pr75gag, of Friend murine leukemia virus (F-MuLV) contains overlapping epitopes, SIVLCCLCL (p71-79) and CCLCLTVFL (p75 83) that activate Friend virus (FV)-induced tumor (FBL-3)-specific cytotoxic T-lymphocytes (CTL) (Kondo et al., J. Virol., 69, 1995, 6735-6741; Chen et al., J. Virol., 70, 1996, 7773-7782). It was investigated whether these two peptides are recognized by a single CTL clone or by individual clones with different specificities. The results show that both hydrophobic and cysteine-containing peptides are bound to H-2Db class I major histocompatibility complex (MHC) molecules and cross-recognized by a single CTL clone as well as bulk-cultured CTL from the spleens of mice immunized with FBL-3. The peptide p71-79 was effective for sensitizing target cells to lysis by CTL in the concentration of common antigenic peptides. Moreover, peptide p75-83 was 1000-fold more potent than the peptide p71-79. Specific cytotoxicity assays with variant peptides with alanine- and serine-substitutions suggested a highly complex function of the disulfide bond-forming peptides potentially sensitive to small sequence differences. The dominance of CTL responses to the transmembrane region is discussed in light of the high affinity of a novel hydrophobic peptide to compete with other peptides for binding to MHC molecules.

p53-independent induction of WAF1/Cip1 is correlated with osteoblastic differentiation by vitamin D3.

1Alpha,25(OH)2 vitamin D3 (1,25(OH)2D3) can induce differentiation of osteoblastic cells by arresting the cell cycle at G1. The p53-inducible gene, WAF1/Cip1, is one of the inhibitors of cyclin-dependent kinases and can inhibit the phosphorylation of retinoblastoma protein (pRB), thereby keeping pRB functionally active. Here we show that in a p53-null human osteoblastic osteosarcoma MG-63 cell line, 10 nM of 1,25(OH)2D3 completely inhibits cell growth and increases alkaline phosphatase activity, which suggests the induction of osteoblastic differentiation. We also found a p53-independent increase of WAF1/Cip1 mRNA and promoter activation by 1,25(OH)2D3. On the other hand, the expression and the promoter activity of the RB gene decreased after treatment with 1,25(OH)2D3 during the differentiation of MG-63 cells. Our results suggest that the p53-independent WAF1/Cip1 induction by 1,25(OH)2D3 is important for osteoblastic differentiation of MG-63 cells.

Establishment of a hemopoietic stimulating factor producing murine leukemia cell lines: pathogenesis of granulocytosis in L8313 bearing mice.

Thy 1.2+ cells of L8313 leukemia bearing mice were previously shown to produce granulocyte macrophage colony stimulating activity (GM-CSA) and interleukin-3 (IL-3). Cell lines with the Thy 1.2+ phenotype were established from spleen cells of the leukemic mice, and were designated STIL-3 C5 and STIL-3 D10. They produced and released GM-CSA and IL-3 activities in culture supernatant. C5 cells were phenotypically Thy 1.2+ and Lyt 2.1+ with rearrangement of the T-cell receptor beta chain gene also being identified. D10 was Thy 1.2+ and L3T4+ with T-cell receptor beta chain gene rearrangement not detectable. Since the same sized rearranged bands were observed between C5 and L8313 leukemic mouse spleen cells, it is indicated that C5 cells are derived from the leukemic cells. Inoculation of these cells into mice induced granulocytosis. These results indicated that L8313, which was thought to be a "granulocytic leukemia", is actually a T-cell leukemia, whose granulocytosis is a leukemoid reaction induced by normal hemopoietic cells responding to the hemopoietic stimulating factors, GM-CSA and IL-3, produced by the leukemic T cells. Thus, L8313 should be known as a T-cell leukemia associated with granulocytosis.

Proliferative response of cloned CTL line 10B-5 upon stimulation with soluble clonotypic monoclonal antibody and its blocking by anti-Lyt-2 antibody.

Proliferation of the cloned cytotoxic T lymphocyte (CTL) line 10B-5 induced by anticlonotypic antibody and its blocking by anti-Lyt-2 mAb were studied. Clone 10B-5 was derived from spleen cells of a (BALB/c x C57BL/6)F1, (CB6F1)-nu/+ mouse immunized with UV female 1 sarcoma. 10B-5 cells lysed UV female 1 specifically and proliferated upon stimulation with UV female 1 and feeder cells in the presence of IL 2. Anti-clonotypic monoclonal antibody (mAb) N1-56 was produced by a hybridoma established by fusion of spleen cells from a CB6F1-nu/+ mouse that had been immunized by five injections of 10B-5 cells prefixed with 0.1% formaldehyde. N1-56 mAb immunoprecipitated 90 kd molecules cleavable to 45 kd molecules under reducing conditions, indicating its reaction with T cell antigen receptor (TCR). N1-56 mAb in its soluble form induced a proliferative response of 10B-5 cells. Thus, the antigen binding site of N1-56 mAb appeared to substitute for the specific antigen determinant on UV female 1 sarcoma. The F(ab')2, but not the Fab fragment of purified N1-56 mAb, stimulated proliferation, indicating that cross-linking of TCR molecules was necessary for stimulation. The proliferative response of 10B-5 cells induced by soluble N1-56 mAb was blocked by addition of anti-Lyt-2.2 mAb to the cultures. The specificity of Lyt-2 blocking was confirmed by an absorption test. The proliferative response of 10B-5 cells induced by Con A, but not that induced by IL 2, was blocked by anti-Lyt-2.2 mAb. These results indicated that blocking by anti-Lyt-2.2 mAb was at an early stage and that it could be bypassed by stimulation with IL2.

Characterization of a CD4(L3T4)-positive cytotoxic T cell clone that is restricted by class I major histocompatibility complex antigen on FBL-3 tumor cell.

An L3T4(CD4)+ CTL clone specific for Friend virus-induced tumor FBL-3 was isolated, characterized and compared with a conventional Lyt-2(CD8)+ CTL clone. This clone L3.1 was obtained from the limiting dilution culture of splenic MLTC cells from a CB6F1 mouse whose CD8+ T cells had been suppressed by an in vivo injection of anti-Lyt-2.2 mAb. The phenotype of clone L3.1 was sIg-, Thy-1.2+, L3T4(CD4)+, Lyt-2 (CD8)-, and Ia- as determined by flow-cytometry. Northern blot analysis also confirmed that mRNA for L3T4(CD4), but not for Lyt-2 (CD8) was present in the total RNA of L3.1. The FBL-3-specific killing activity of L3.1 was inhibited by anti-H-2D6 mAb, and the tumor cells did not express class II MHC antigen, indicating that the recognition of tumor antigen by this CD4+ CTL clone was restricted by the class I MHC molecule on the tumor cells. Furthermore, the finding that anti-L3T4(CD4) mAb GK1.5 inhibited the specific and lectin-dependent non-specific cytotoxicity of L3.1 suggested that CD4 molecules on this CTL clone are not ligand (MHC class II)-binding proteins, but are involved in signal transduction.