A stable Escherichia coli-mycobacteria shuttle vector 'pSO246' in Mycobacterium bovis BCG

The most widely used plasmid vector system in mycobacteria is based on pAL5000 from Mycobacterium fortuitum. The derivatives of the pAL5000-based shuttle vectors between Escherichia coli and mycobacteria, which we have utilized to secrete recombinant antigens, were generated. The stability of the vectors was assessed in Mycobacterium bovis BCG (BCG). The plasmid vector pSO246 was stable in BCG for at least 50 generations.

Neonatal changes of osteoclasts in osteopetrosis (op/op) mice defective in production of functional macrophage colony-stimulating factor (M-CSF) protein and effects of M-CSF on osteoclast development and differentiation

In mice homozygous for the osteopetrosis (op) mutation, loss of osteoclasts in the postnatal period and their development, differentiation, and maturation following daily M-CSF administration in adult life were investigated. Histochemical, immunohistochemical, and ultrastructural approaches, as well as [3H]thymidine autoradiography, clarified the role of M-CSF on osteoclast development and differentiation. In op/op mice osteoclasts appeared normal at birth. However, osteoclast numbers were reduced within a few days after birth, and osteoclasts were undetectable by 3-4 days of age. In adult op/op mice there were no multinuclear osteoclasts; however, small numbers of mononuclear cells (so-called 'preosteoclasts') were observed on the endosteal surface of bone. These preosteoclasts expressed tartrate-resistant acid phosphatase and showed ultrastructural features of immature osteoclasts. After daily M-CSF administration in op/op mice, osteoclasts developed from the fusion of preosteoclasts and osteoclasts numbers increased to the levels of normal littermates at 3 days. Autoradiographic analysis with [3H]thymidine revealed no labeling in osteoclasts and preosteoclasts. In the mutant mice, M-CSF administration induced numerical increases of monocytes, promonocytes, and earlier precursor cells in bone marrow, ER-MP12- or, ER-MP58-positive granulocyte/macrophage colony-forming cells (GM-CFCs). Among these macrophage precursors, ER-MP58-positive cells were considered preosteoclast precursors, and possessed marked proliferative potential. These data suggest that an ER-MP58-positive cell subpopulation of GM-CFCs proliferates in response to M-CSF, differentiates into preosteoclasts which fuse with each other to develop into mature osteoclasts.

Identification of actin as a substrate of ICE and an ICE-like protease and involvement of an ICE-like protease but not ICE in VP-16-induced U937 apoptosis

Human leukemia U937 cells are induced to undergo apoptosis by several chemotherapeutic agents; however, the cellular components involved in the process have not yet been identified. We found that an actin-cleavage activity (ACA) was activated in the VP-16-treated U937 cytosolic fraction and 15K- and 30K-actin fragments were produced. This ACA was inhibited by inhibitors of interleukin-1 beta-converting enzyme (ICE)/ced-3 family proteases, such as Z-Asp-CH2-DCB, YVAD-CHO, TPCK, TLCK, and iodoacetamide. Differing from ICE, the ACA could not process pro-IL-1 beta to mature IL-1 beta. Although ICE can cleave actin in vitro, ICE activity was not activated in the VP-16 treated U937 cells. These results indicate that actin is a potential substrate of ICE and ICE-like proteases, and that VP-16 preferentially activate an ICE-like protease, but not ICE itself, in U937 cells.

Peripheral lung carcinomas associated with central fibrosis and mixed small cell and other histologic components

Three cases of peripheral small cell lung carcinoma (SCLC) with central fibrosis are presented. Central fibrosis is usually present in adenocarcinomas. Cases 1 and 2 are combined SCLCs with components of papillary adenocarcinoma, and case 3 is a mixed SCLC with a large cell component. Small cell components showed intermediate cell type in all cases. In cases 1 and 2, there was a gradual transition between small cell carcinoma and papillary adenocarcinoma. Small cell components showed Grimelius argyrophilia, but other neuroendocrine markers such as neuron specific enolase, chromogranin A, Leu-7 and synaptophysin were negative. The chest X-ray examination of case 1 demonstrated rapid enlargement of a tumor shadow, which was present two years before, for a recent year. Central fibrosis, coexistence of small cell carcinoma and papillary adenocarcinoma, and a change of growth rate in the chest X-ray may suggest that some SCLC derive from papillary adenocarcinomas.

Supportive cellular elements for hepatic T cell differentiation: T cells expressing intermediate levels of the T cell receptor are cytotoxic against syngeneic hepatoma, and are lost after hepatocyte damage

Extrathymic T cells exist in the liver and are often seen in close contact with Kupffer cells in the hepatic sinusoids. Since selective depletion of Kupffer cells has become possible by using liposome-encapsulated clodronate, it was investigated whether elimination of Kupffer cells influences the level of extrathymic T cells in the liver. Extrathymic T cells were identified as interleukin-2 receptor beta-chain (IL-2R beta) intermediate TCR (TCRint) cells by two-color staining for CD3 or T cell receptor (TCR) and IL-2R beta. The elimination of Kupffer cells did not significantly affect levels of TCRint cells up to 7 days after treatment. We then examined monocyte colony stimulating factor (M-CSF)-deficient op/op mice (low levels of Kupffer cells). Extrathymic T cells both in the liver and spleen of these mice were detected at a level comparable to that of control mice. Since extrathymic T cells in the liver are sometimes located in the parenchymal space, the relationship between extrathymic T cells and hepatocytes was then examined. Electron microscopy revealed that some hepatic T cells adhered directly to hepatocytes. When hepatocytes were damaged by a single injection of CCl4, hepatocyte death and subsequent hepatic fibrosis were induced. Beginning 3 days after injection, CD3int cells, but not other type of cells, decreased prominently. Purified CD3int cells, as well as whole lymphocytes in the liver, were cytotoxic against syngeneic hepatoma. In parallel with the above-mentioned hepatic damage, the cytotoxic activity of lymphocytes against such targets was impaired in the liver. These results suggest that extra-thymic generation of TCRint cells and their acquisition of cytotoxic function are relatively independent of Kupffer cells, but are dependent on hepatocytes.

Classification of air density areas in CT-pathologic correlation of pulmonary adenocarcinoma

Air density areas (ADAs) such as air bronchogram, bubble-like area, and cavity on high resolution computed tomography (HRCT) of pulmonary adenocarcinoma were examined to clarify their pathological implications. Forty-two resected specimens of pulmonary adenocarcinoma were histopathologically examined in correlation with the HRCT findings with particular emphasis on ADAs. Forty-one ADAs observed in 32 of 42 cases with pulmonary adenocarcinoma were classified into three types: air bronchogram type (n = 22), bubble-like area type (n = 12), and cavity type (n = 8). Twenty of 22 air bronchogram ADAs corresponded to bronchi. Nine of 12 bubble-like area ADAs corresponded to bronchioles. Only one of eight cavity-ADAs consisted of necrosis. The classification of ADAs in pulmonary adenocarcinoma is considered to be useful in interpreting HRCT findings of pulmonary nodules.

[The role of some cellular components of bacterial parasites in determining the incidence of tuberculosis: studies on mycobacterial antigens, with special reference to mycobacterial immunoreactive ribosomal and secreted proteins]

Tuberculosis remains as major disease, affecting more than 20 million people. The elimination of the disease with vaccination, rapid diagnosis, and and efficient therapy is an important objective of our study. To realize the objective, the characterization of antigens is essential. We have chosen two kinds of antigens for our study, the ribosomal antigens and and an antigenic proteins secreted by mycobacteria. The biochemical and immunological characterization of ribosomal fraction was carried out. Ribosomal proteins were purified and assessed for DTH reaction. The N-terminal amino acids sequences were determined. Total structures of S19, S7 and S12 in 30S and L7/L12 in 50S subunits were elucidated. L7/L12 had 66% homology with analogue from S. griseus which showed GTPase activity in protein synthesis. This protein was secreted in culture medium and induced strong DTH. Secreted antigenic proteins are of great interest for us. Secreted antigens may be recognized rapidly by immune system and therefore may induce rapid and high level immune response. It is also expected that it may contain protective antigens, since live BCG protect disease more efficiently than heat killed BCG. We have determined and published the total structure of four proteins (MPB64, MPB70, MPB57 and alpha antigen). We attempted to utilize this antigen for the diagnosis and the design of vaccine. The structures of alpha antigens from M. avium, M. intracellulare, M. scrofulaceum, M. kansasii and BCG were determined and its potential for application to diagnosis was presented. Using the operon of M. kansasii, alpha antigen and V3 region of HIV-1 were expressed by recombinant BCG which induced CTL in mice.

Cloudy nodule on HRCT: a new clinico-radiologic entity of pulmonary adenocarcinoma

We propose cloudy nodule (CN) on HRCT as a special type of pulmonary adenocarcinoma. CN was defined as a cloudy nodular shadow in the peripheral part of the lung with lower density than pulmonary vessels on HRCT. Radiologic images of nine CNs in eight cases were correlated with the pathological findings of the resected specimen. All CNs were clearly demarcated on HRCT. They were pathologically composed of well differentiated adenocarcinoma, mainly bronchioloalveolar type with little or no central scar. Plain films were negative in six of nine cases. CN on HRCT may indicate well-differentiated adenocarcinoma with good prognosis.

Pulmonary myxoid leiomyosarcoma

A primary myxoid leiomyosarcoma arising from the peripheral bronchus of the right middle lobe was removed from a 20 year old man and examined by immunohistochemistry and electron microscopy. The tumor was well circumscribed, yellow-whitish focal polypoid growth into the bronchial lumen and consisted of spindle cells with abundant myxoid substance in the stroma. Intrapulmonary metastasis, invasion to the bronchial wall and a few mitotic figures were found. Immunohistochemically, several, but not all, tumor cells were positive against anti-vimentin, anti-S-100 protein, anti-myosin and anti-muscle specific actin. Ultrastructurally, tumor cells had thin filaments with dense bodies, pinocytic vesicles and discontinuous basal lamina. These findings indicate a myoxoid variant of leiomyosarcoma arising from mesenchyme in the peribronchial area.

Expression of the c-kit gene product in normal and neoplastic mast cells but not in neoplastic basophil/mast cell precursors from chronic myelogenous leukaemia

The expression of the c-kit gene product has been examined in normal mast cells, mast cell neoplasms, and basophil/mast cell precursors obtained from patients with chronic myelogenous leukaemia (CML). Formalin-fixed, paraffin-embedded sections or smears fixed with formalin vapour were studied by immunohistochemical methods, using a polyclonal antibody against the c-kit gene product. Normal and neoplastic mast cells showed a positive immunoreaction for c-kit gene product, but neoplastic basophil/mast cell precursors from CML patients lacked c-kit gene product by immunohistochemical and flow cytometric methods, even in cells having mast cell granules, together with or without basophil granules. Mast cell tryptase was, however, expressed in normal and neoplastic mast cells and basophil/mast cell precursors containing mast cell granules. In addition, cells of monocyte/macrophage lineage lacked c-kit gene product. These findings indicate that the c-kit gene product may play an important role in the development and function of mast cell but not of cell of basophil and monocyte/macrophage lineage.

A recessive mutant of the U937 cell line acquired resistance to anti-Fas and anti-p55 tumor necrosis factor receptor antibody-induced apoptosis

Human monocytic leukemia U937 cells readily undergo apoptosis when cells are treated with various stimuli including antitumor agents, tumor necrosis factor (TNF)-alpha and anti-Fas antibody. However, the signal transduction mechanism resulting in apoptosis is unclear. To study the mechanism of apoptosis, we isolated and characterized a mutant, UK110, from U937 cells, which was resistant to TNF-alpha and anti-Fas antibody-induced apoptosis but was less resistant to etoposide-induced apoptosis. TNF-alpha induced signals are mediated by two types of TNF receptors (TNFR), p55- and p75-TNFR, and p55-TNFR is homologous to the Fas antigen. Interestingly, UK110 cells showed resistance to apoptosis by agonistic anti-p55-TNFR antibody, indicating that UK110 cells were resistant to Fas- and p55-TNFR-mediated apoptosis. Because expression of apoptosis-associated molecules, such as c-Myc, Bcl-2, and Bax, was similar between U937 and UK110 cells an undetermined pathway for apoptosis through Fas and p55-TNFR could be mutated in UK110 cells. To clarify the genetic phenotype of UK110 cells, we performed somatic cell hybridization with parental U937 and the UK110 cells. All of the hybrid clones were as sensitive as the parental U937 cells to apoptosis by both anti-Fas and anti-p55-TNFR antibodies, indicating that the apoptosis resistance in UK110 cells resulted from recessive genotype.

Induction of hepatic P-glycoprotein enhances biliary excretion of vincristine in rats

To clarify the contribution of P-glycoprotein to the biliary excretion of vincristine in rats, the effects of induction of hepatic P-glycoprotein by a phenothiazine treatment on the biliary excretion of [3H]vincristine were investigated. Immunoblot analysis using C219, a monoclonal antibody to P-glycoprotein, demonstrated that the phenothiazine treatment increased the P-glycoprotein level in isolated bile canalicular membrane vesicles approximately 6.5-fold. Transport of [3H]vincristine to canalicular membrane vesicles from the phenothiazine-treated and control rats revealed ATP-dependency, with an overshoot that results from the consumption of medium ATP. The maximum ATP-dependent uptake was increased in canalicular membrane vesicles from the phenothiazine-treated rats approximately 2-fold compared to the control. The biliary excretion of [3H]vincristine was further studied using an indicator dilution method in a single-pass perfused liver. The ratios of the cumulative amount of [3H]vincristine excreted into the bile ot the amount of [3H]vincristine taken up by the liver at 15, 30 and 90 min were significantly increased in the phenothiazine-treated rats by 60, 45 and 25%, respectively, compared to the control rats. Furthermore, the corrected mean residence time of [3H]vincristine in hepatocytes in the phenothiazine-treated rats was reduced to 21 min from that in the control rats (30 min), supporting the contention that the induction of hepatic P-glycoprotein on the bile canalicular membrane function sas a transporter not only in the isolated membrane but also in the more physiological perfused liver system. One must be cautious in the interpretation of the data, however, since phenothiazine can induce other proteins which might affect the behavior of [3H]vincristine.

Reconstitution of purified P-glycoprotein into liposomes

To study the molecular function of the multidrug-resistance gene product P-glycoprotein, we purified and reconstituted it into liposomes. Twelve detergents were examined in an attempt to solubilize and reconstitute the transport activity of K562/ADM membrane proteins containing P-glycoprotein. We found that transport activity was effective reconstituted after solubilization with cholate, glycocholate and taurocholate. Other detergents, such as CHAPS, Triton X-100 and deoxycholate, diminished the transport activity. The K562/ADM membrane was solubilized by 1% glycocholate, and P-glycoprotein was purified by MRK-16 immunoaffinity column chromatography to a homogeneous single band on sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The purified P-glycoprotein was reconstituted by detergent dialysis into liposomes composed of phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine. The reconstituted P-glycoprotein specifically bound [3H]azidopine and had an ATPase activity that was slightly stimulated when vincristine was added. Furthermore, though its activity was reduced, the reconstituted P-glycoprotein was shown to be an ATP-dependent transporter of vincristine.

Induction of angiogenesis by smooth muscle cell-derived factor: possible role in neovascularization in atherosclerotic plaque

The development of atherosclerotic plaque is associated with neovascularization in the thickened intima and media of vascular walls. Neovascularization may have a role in the progression of atherosclerotic plaque as well as in the development of intraplaque hemorrhage. However, the mechanism and stimulus for neovascularization in atherosclerotic plaque are unknown. We postulated that smooth muscle cells (SMCs), a major cellular component in the vascular wall, might contribute to the induction of neovascularization in atherosclerotic plaque through the secretion of an angiogenic factor. We observed that endothelial cells (ECs) cultured on collagen gel with SMC-conditioned medium became spindle shaped, invaded the underlying collagen gel, and organized a capillary-like branching cord structure in the collagen gel. The conditioned medium also stimulated EC proliferation and increased the EC-associated plasminogen activator activity. The angiogenic factor in SMC-conditioned medium was retained in a heparin-Sepharose column and eluted with 0.9 M NaCl. Neutralizing anti-vascular endothelial growth factor (VEGF) antibody attenuated the angiogenic activity in the conditioned medium, including the induction of morphologic changes in ECs, mitogenic activity, and increased plasminogen activator activity associated with ECs. Immunoblotting analysis confirmed the secretion of VEGF from SMCs. These observations indicate that SMC may be responsible for the neovascularization in atherosclerotic plaque through the secretion of VEGF.

New approaches to the prevention of atherosclerosis

In recent years, remarkable progress has been made in the prevention and treatment of atherosclerosis. However, much of the research has been devoted to the investigation of lipid metabolism and lipid-lowering drugs. This review highlights some recent topics in both experimental and clinical investigations, with emphasis on studies other than those on lipid-lowering drugs. These topics include oxidative modification of lipoproteins, hyperfibrinogenaemia, hyperhomocysteinaemia, female sex hormones and endothelium-derived relaxing factor (or nitric oxide). Some of these approaches have already been applied in the clinic.

Hepatitis C viral quasispecies in hepatitis C virus carriers with normal liver enzymes and patients with type C chronic liver disease

Hepatitis C virus (HCV) has been reported to conform to a quasispecies nature, which is most evident in hypervariable regions of the putative envelope 2 domain. The aim of this study was to determine the relationship between the nucleotide complexity and diversity of hypervariable region 1 and various stages of the carrier states. The subjects studied were 20 HCV carriers with normal alanine aminotransferase (ALT) levels, 50 patients with chronic hepatitis who showed elevated ALT levels, 22 with cirrhosis, and 24 with hepatocellular carcinoma. The quasispecies complexity was analyzed by means of polymerase chain reaction-mediated single strand conformation polymorphism (PCR-SSCP). The value of nucleotide diversity was calculated by PCR cloning and sequencing. The number of SSCP bands ranged from 1 to 7, with no significant differences in the mean numbers among the stages of HCV infection. There was no correlation between the amounts of serum HCV RNA and the numbers of SSCP bands. No significant difference was found in the values of nucleotide diversity between carriers with normal ALT levels (mean, 6.6 x 10(-2) per site) and patients with chronic hepatitis (7.7 x 10(-2). These findings suggest that the quasispecies complexity of hypervariable region 1 is independent of the stage of chronic HCV infection.

Germ line chimera produced by transfer of cultured chick primordial germ cells

Intrinsic primordial germ cells (PGCs) from stage 27 (5-day-old) chick embryonic germinal ridges were cultured in vitro for a further 5 days, and shown to proliferate on stroma cells derived from the germinal ridge. To determine whether these cultured PGCs could colonize and contribute to the germ-line, PGCs were isolated by gentle pipetting, labeled with PKH26 fluorescent dye and injected into the blood stream of stage 17 (2.5-day-old) chick embryos. The recipient embryos were incubated until they reached stage 28. Thin sections of these embryos were analysed by fluorescent confocal laser microscopy. These analyses showed that the labeled donor PGCs had migrated into the germinal ridges of the recipient embryos, and transplanted PGCs had undergone at least 3-7 divisions. These results suggest that PGCs that had passed far beyond the migration stage in vivo were still able to migrate, colonize and proliferate in recipient chick embryonic gonads.

Reversal of multidrug resistance by a novel quinoline derivative, MS-209

MS-209, a novel quinoline derivative, was examined for its reversing effect on multidrug-resistant tumor cells. MS-209 at 1-10 microM completely reversed resistance against vincristine (VCR) in vitro in multidrug-resistant variants of mouse leukemia P388 cells (VCR-resistant P388/VCR and Adriamycin (ADM)-resistant P388/ADM) and human leukemia K562 cells (VCR-resistant K562/VCR and ADM-resistant K562/ADM). MS-209 at 1-10 microM also completely reversed resistance against ADM in vitro in P388/VCR cells, K562/VCR cells, and K562/ADM cells. In ADM-resistant P388 (P388/ADM) cells, however, ADM resistance was only partially reversed at the MS-209 concentrations tested. MS-209 enhanced the chemotherapeutic effect of VCR in P388/VCR-bearing mice. When MS-209 was given p.o. at 80 mg/kg twice a day (total dose, 160 mg/kg per day) with 100 micrograms/kg VCR, a treated/control (T/C) value of 155% was obtained. MS-209 also enhanced the chemotherapeutic effect of ADM in P388/ADM-bearing mice. The most prominent effects were obtained when MS-209 was given with 2 mg/kg ADM, yielding T/C values of 150%-194% for the combined treatment at an MS-209 dose of 200-450 mg/kg. MS-209 inhibited [3H]-azidopine photolabeling of P-glycoprotein efficiently. Furthermore, the accumulation of ADM in K562/ADM cells was increased more efficiently by MS-209 than by verapamil. These results indicate that MS-209, like verapamil, directly interacts with P-glycoprotein and inhibits the active efflux of antitumor agents, thus overcoming multidrug resistance in vitro and in vivo.

The role of macrophage colony-stimulating factor in the differentiation and proliferation of Kupffer cells in the liver of protein-deprived mice

BACKGROUND

Protein calorie malnutrition is known to induce various macrophage dysfunctions, such as the impairment of their phagocytic function, proliferative capacity, and bactericidal activity. However, little is known about the behavior of Kupffer cells under protein calorie malnutrition in vivo.

EXPERIMENTAL DESIGN

To investigate the behavior of Kupffer cells under protein calorie malnutrition, we fed mice on a low protein (protein-derived) diet for 4 weeks and examined the number, cytologic changes, and proliferative capacity of their Kupffer cells. To detect macrophage precursor cells, colony-forming assays were performed in the bone marrow, spleen, and liver of the mice. To investigate the relationship of Kupffer cells to CSF, the serum levels of IL-6 and granulocyte-macrophage colony-stimulating factor were measured by ELISA, and the expression of macrophage colony-stimulating factor (M-CSF) mRNA in the liver was determined by Northern blot analysis. The recovery processes of Kupffer cells in the protein-deprived mice after normal protein feeding or daily recombinant human macrophage colony-stimulating factor administration were also investigated.

RESULTS

In the protein-deprived mice, Kupffer cells decreased in number to two-thirds that of the normally fed (nondeprived) mice, showed the cytologic and ultrastructural features of maturation failure, and had reduced proliferative capacity. After normal protein feeding or recombinant human macrophage colony-stimulating factor administration, the number, morphology, and proliferative capacity of the Kupffer cells in the liver returned to normal, and they matured as in the nondeprived mice. In the protein-deprived mice, the serum levels of IL-6 and granulocyte-macrophage colony-stimulating factor increased, and the expression of M-CSF mRNA in the liver was reduced. In the bone marrow, the granulocyte-macrophage colony-forming cells and macrophage colony-forming cells were increased, and the influx of monocytes into the liver was temporarily enhanced; however, the number of monocytes in the peripheral blood was decreased.

CONCLUSIONS

These results suggest that the reduced production of M-CSF in the liver of protein-deprived mice results in numerical reduction, maturation failure, and decreased proliferative capacity of Kupffer cells.

Non-X histiocytoma, similar to fibrous histiocytoma, in an infant

A case is presented of a female infant with an atypical histiocytoma. A gradually enlarging brown lesion was noted on the left side of the chest at the age of 2 weeks. Microscopic study of a biopsy revealed an ill-defined infiltration of spindle cells with indented nuclei. The tumor cells were positive for CD14, HLA-DR, lysozyme, alpha-1-antitrypsin and alpha-1-antichymotrypsin, and negative for CD1, CD3, CD8, CD10, CD19, CD68 and S-100 by immunohistochemistry. Electron microscopy demonstrated no distinct Birbeck's granules, but aberrant granules were seen in a small number of cells. At 7 months of age, a nodule with similar histologic features was noted in the nuchal region, but was incompletely resected. The patient remains recurrence-free at 36 months of age. This case is thought to be a benign form of non-X histiocytoma.

Involvement of CD45 in adhesion and suppression of apoptosis of mouse malignant T-lymphoma cells

Mouse malignant T-lymphoma CS-21 cells undergo apoptotic cell death in vitro in the absence of lymph node stromal cells but escape apoptosis and proliferate when they are attached to CA-12 stromal cells. A monoclonal antibody raised against CS-21 cell surface molecules (MCS-5) recognized a M(r) 168,000 protein, inhibited binding of CS-21 cells to CA-12 stromal cells, and suppressed apoptosis in CS-21 cells. To identify the M(r) 168,000 protein, we purified it with MCS-5 affinity chromatography and ion exchange chromatography. Partial amino acid sequences of the purified M(r) 168,000 protein were identical to those of CD45, a transmembrane tyrosine phosphatase. The purified protein possessed tyrosine phosphatase activity and was recognized by an anti-CD45 monoclonal antibody. The M(r) 168,000 protein was identified as CD45. To determine the CD45 isoform, we cloned the CD45 gene from the cDNA library of CS-21. Sixteen of 18 clones encoded CD45RO (CD45 lacking exons 4, 5, and 6), and the remainder lacked exons 4, 5, 6, and 7. Like MCS-5, an anti-CD45 monoclonal antibody, also inhibited binding of CS-21 cells to CA-12 cells and suppressed apoptosis in CS-21 cells. Our present results indicate that CD45RO expressed on CS-21 cells mediates adhesion to CA-12 cells and suppression of apoptosis.

Characterization of the gene encoding the MPB51, one of the major secreted protein antigens of Mycobacterium bovis BCG, and identification of the secreted protein closely related to the fibronectin binding 85 complex

The secreted protein MPB51 is one of the major proteins in the culture filtrate of Mycobacterium bovis BCG (BCG) and is a protein immunologically cross-reacting with the fibronectin binding 85 complex secreted by this bacterium. The gene encoding MPB51 (mpb51) was cloned, sequenced, and expressed in Escherichia coli. The mpb51 gene was mapped downstream of the gene for 85A component with 179 bp spaces. The mpb51 gene encoded 299 amino acids, including 33 amino acids for the signal peptide, followed by 266 amino acids for the mature protein with a molecular mass of 27807.37 Da. This is the first complete sequence of MPB51. MPB51 showed 37-43% homology to the components of 85 complex. Two-dimensional electrophoresis of culture fluids of BCG and Western blotting indicated the existence of the other novel protein(s) which strongly cross-reacted with the alpha antigen (85B) and MPB51.