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T Hamaoka

Publications and source records attributed to T Hamaoka.

At least 163 records · Page 9Linked to original sources
PubMed1990

Monoclonal antibodies to Pgp-1/CD44 block lympho-hemopoiesis in long-term bone marrow cultures.

A new panel of mAbs was prepared to a stromal cell line known to support lymphocytes in Whitlock-Witte type long-term bone marrow cultures. These antibodies were then screened with a cell adhesion assay and four were selected that inhibited the binding of B lineage cells to stromal cell monolayers. Immunofluorescent and biochemical analyses revealed that these new antibodies detected epitopes of the previously described Pgp-1/CD44 antigen complex. Addition of Pgp-1/CD44 antibodies to Dexter-type long-term bone marrow cultures completely prevented emergence of myeloid cells and they also blocked lymphocyte growth in Whitlock-Witte type cultures. mAbs MEL-14, LFA-1, and CD45R did not inhibit under the same conditions and there was no apparent relationship to Ig isotype. Adherent layers in treated cultures were not unusual in terms of morphology and the antibodies did not affect factor-dependent replication of lymphoid or myeloid progenitor cells. Therefore, the mechanism of inhibition may not involve direct toxicity to precursors or microenvironmental elements. Previous studies in humans and mice have implicated Pgp-1/CD44-related glycoproteins in the migration of peripheral lymphoid cells, as well as interactions of cells with the extracellular matrix. These findings suggest that they may also be critical for formation of lymphoid and myeloid cells within bone marrow.

Animals↗
PubMed1990

IL-5 up-regulates but IL-4 down-regulates IL-2R expression on a cloned B lymphoma line.

Both IL-4 and IL-5 demonstrate B cell growth activity. IL-5 can render a cloned neoplastic B cell line, BCL1-CL-3 cells, responsive to IL-2, whereas IL-4 has no such activity. The response to IL-5 and IL-2 proceeds in two phases: the first phase which clearly depends upon IL-5 is the obvious increase in number of high affinity IL-2R (3.1-fold) with modest increase of low affinity IL-2R (1.2-fold) and gain of the ability of facilitated IL-2-binding and internalization of IL-2, and the second phase which is induced by IL-2 in the IL-5-stimulated CL-3 cells comprises the striking increase of low affinity IL-2R (8.5-fold). Kinetic study has revealed that high affinity IL-2R expressed on CL-3 cells begins to increase at 6 h and reaches to maximum at 12 h after stimulation with IL-5 or IL-5 plus IL-2, whereas low affinity IL-2R expression increases at 18 h and becomes maximal at 24 h after stimulation of CL-3 cells with IL-5 and IL-2. However, in the presence of IL-4, IL-5 cannot induce an increase in number of high affinity IL-2R on CL-3 cells. Thus, CL-3 cells stimulated with the mixture of IL-5 and IL-4 cannot respond to IL-2, and fail to show up-regulated expression of low affinity IL-2R. IL-4 also has a capacity to modestly interfere with the action of IL-2 to up-regulate low affinity IL-2R expression on IL-5-pretreated CL-3 cells. Thus, this monoclonal B cell system provides an excellent model system to define the roles of IL-5 and IL-4 involved in the B cell differentiation and to characterize the properties of B cells competent to IL-2 stimulation and the signal transduction mechanism which operates through IL-2/IL-2R system.

Animals↗
PubMed1990

Thymic stroma-derived T cell growth factor (TSTGF): III. Its ability to promote T cell proliferation without stimulating interleukin 2- or 4-dependent autocrine mechanism.

A thymic stroma-derived cell clone, MRL104.8a produced a T cell growth factor designated as thymic stroma-derived T cell growth factor (TSTGF). This factor that is distinct from previously described T cell growth factors such as interleukin (IL) 2 or 4 was capable of promoting the growth of IL2-dependent, antigen-specific helper T cell clones. While such growth promotion was induced without requirement of the relevant antigen and exogenous IL2, we further investigated whether it depended on activation of an IL2- or IL4-dependent autocrine mechanism. Helper T cell clones, 8-E and 8-5, were able to proliferate in response to stimulation with either antigen or TSTGF. 8-E and 8-5 produced IL2 and IL4, respectively, in cultures following antigenic stimulation, whereas neither IL2 nor IL4 activity was detected in cultures during TSTGF-induced proliferation. The proliferation of these helper T cell clones by antigenic stimulation was almost completely inhibited when anti-IL2 receptor or anti-IL4 antibody was added to the cultures. The addition of cyclosporin A (CsA) to cultures of 8-E and 8-5 clones together with antigen also resulted in the complete inhibition of cellular proliferation in association with the suppression of IL2 and IL4 production. In contrast, TSTGF-induced proliferation was not affected by addition of either type of antibody or CsA. These results indicate that TSTGF is a novel T cell growth factor that can exert its own growth-promoting effect without depending on an IL2- or IL4-operating autocrine mechanism.

Animals↗
PubMed1990

Immune dysfunction expressed selectively on L3T4+ T cells in the tumor-bearing state.

Spleen cells from normal C3H/He or BALB/c mice generate cytotoxic T-lymphocyte (CTL) responses to both trinitrophenyl (TNP)-modified syngeneic cells (TNP-self) and allogeneic cells. In contrast, cells from these strains of mice bearing a syngeneic tumor failed to induce anti-TNP-self-CTL responses, although portions of the same responding cells generated comparable anti-allo-CTL responses to those induced by normal responding cells. Although anti-allo-CTL responses were inducible from only Lyt-2+ T-cell subset of responding cells from normal or tumor-bearing mice, induction of TNP-CTL responses required the participation of L3T4+ T-cell subset as well as Lyt-2+ CTL precursors. In addition, the fact that the addition of concanavalin A-stimulated culture supernatant to cultures of responding cells from tumor-bearing mice resulted in the induction of appreciable anti-TNP-self CTL responses demonstrated the defect of L3T4+ T-cell function in the tumor-bearing state. Such a functional defect was ascribed neither to the loss of L3T4+ T cells nor to the generation of suppressor cells in spleen cells of tumor-bearing mice. It was found on one hand that in vitro stimulation of antigen-presenting cell (APC)-depleted normal responding population with TNP-self prepared from cells of normal or tumor-bearing mice produced comparable anti-TNP CTL responses. On the other hand, APC-depleted responding cells from tumor-bearing mice were unable to induce anti-TNP CTL responses under conditions in which APC-depleted normal responding cells induced an effective TNP-CTL response. These results indicate that selective impairment of L3T4+ T cell-mediated immunity is induced in the tumor-bearing state and that such an impairment is ascribed to the dysfunction of L3T4+ T cells themselves, but not of APC required for the activation of L3T4+ T-cell subset.

Animals↗
PubMed1990

Involvement of I-A-restricted B-B cell interaction in the polyclonal B cell differentiation induced by lipopolysaccharide.

The present study has examined a functional role of Ia molecules expressed on murine B cells in polyclonal B cell differentiation induced by lipopolysaccharide (LPS). Reverse, IgM PFC responses of unprimed B cells induced by LPS in the apparent absence of T cells and adherent accessory cells were markedly inhibited in a haplotype-specific manner by Fab monomer fragment of anti-class II (Ia) but not anti-class I MHC monoclonal antibody (mAb). However, the degree of inhibition of LPS responses of H-2-heterozygous F1 B cells expressing both parental I-A products by either one of anti-I-A mAb was at best half that of the parental B cells. Interestingly, when (B10 x B10.-BR)F1 (H-2b/k) B cells were fractionated into adherent and nonadherent populations by their ability to bind to parental B10 B cell monolayers, LPS responses of F1 B cells adherent to and nonadherent to the B10 B cell monolayers were selectively inhibited by anti-I-Ab and anti-I-Ak mAb, respectively. These results suggest that LPS-responsive F1 B cells comprise at least two separate populations with restriction specificity for only one of the parental I-A products expressed on B cells. In addition, it was demonstrated that the I-A-restriction specificity of LPS-responsive B cells is "plastic" and determined by H-2-genotype of bone marrow cells present during B cell ontogeny but not by that of radiation-resistant host elements. Namely, the LPS responses of B10-derived B cells from (B10 + B10.BR) (H-2b x H - 2k)F1 radiation bone marrow chimeras but not from B10 (H-2b x H-2k)F1 chimeras became sensitive to the inhibition of anti-I-Ak mAb in the presence of mitomycin C-treated I-Ak-positive B cells, supporting a notion of receptor-Ia molecules interactions rather than like-like interactions. Thus, the present results provide evidence indicating that B-B cell interaction via recognition of self-I-A products is a crucial event in the polyclonal B cell differentiation induced by LPS.

Animals↗
PubMed1990

Differentiation of thymocytes from CD3-CD4-CD8- through CD3-CD4-CD8+ into more mature stages induced by a thymic stromal cell clone.

We have investigated the capacity of our established thymic stromal cell clone (MRL104.8a) or its derived factor(s) to induce the differentiation of immature thymocytes. Culture of purified adult murine double-negative (CD4-CD8-, indicated here as CD4-8-) thymocytes on the MRL104.8a thymic stromal cell monolayer for 1 day resulted in the induction of an appreciable percentage of CD4-8+ thymocytes. A bone marrow-derived stromal cell monolayer or a L929 fibroblast monolayer failed to generate CD4-8+ cells. This differentiation could also be induced by a semipurified sample of the MRL104.8a culture supernatant, which contained a thymic stroma-derived T-cell growth factor capable of contributing to the growth of double-negative immature thymocytes. CD4-8+ thymocytes generated 1 day after coculture with the MRL104.8a cells or the sample containing thymic stroma-derived T-cell growth factor were found to be CD3- and J11d+, excluding the possibility of expansion of mature (CD3+4-8+) thymocytes present in the thymus. More importantly, when the culture period was extended to 2 or 3 days, an appreciable number of CD4+8+ and single-positive (CD4+) cells were generated on the MRL104.8a monolayer. Thus, these results provide the direct demonstration that CD3-4-8- immature thymocytes are promoted to differentiate through a rapidly cycling intermediate (CD3-4-8+) into double- and single-positive cells by a specialized thymic stromal component.

Animals↗
PubMed1990

B-B cell interaction involved in polyclonal B cell activation is restricted by I-A but not by I-E molecules.

We have previously demonstrated that the class II MHC restricted B-B cell interaction is involved in the polyclonal differentiation of unprimed murine B cells into IgM-producing cells induced by a T cell-derived lymphokine B151-TRF2 or bacterial LPS. The present study has addressed the question of whether I-A and/or I-E molecules function as restriction elements for the B-B cell interaction. The results revealed that (B10 x B10.BR)F1(H-2b/k) B cells could be separated into I-Ab- and 1-Ak-restricted subpopulations by their ability to bind to B10(H-2b) or B10.BR(H-2k) B cell monolayers, whereas an I-E-restricted F1 B cell population was not obtained. Moreover, B10-derived B cells isolated from (B10 + B10.BR) - (B10 x B10.BR)F1 but not from B10 - (B10 x B10.BR)F1 radiation-induced bone marrow chimeras acquired newly the ability to co-operate with mitomycin C-treated auxilary B cells expressing I-Ak but not I-Ek molecules. Thus, these results indicate that I-E molecules, unlike I-A molecules, do not serve as restriction elements for the B-B cell interaction, and that I-A and I-E molecules on B cells play functionally disparate roles in the activation of polyclonal B cells.

Animals↗
PubMed1990

Autoimmune thyroiditis induced in mice depleted of particular T cell subsets. III. Analysis of regulatory cells suppressing the induction of thyroiditis.

It has previously been demonstrated that T cell clones with potentials to induce autoimmune thyroiditis exist in lymphoid organs from normal healthy individuals. The present study investigates the nature of regulatory cells co-existing in a normal lymphoid cell population to prevent the activation of these thyroiditis-inducing T cells. T cell-depleted (C57BL/6 x C3H/He) F1 mice (B cell mice) were prepared by adult thymectomy and injection of anti-thymocyte serum, followed by lethal X-irradiation and bone marrow reconstitution. Typical thyroiditis was induced in these B cell mice by i.v. administration of Lyt-1dull T cells but not of whole T cells from normal syngeneic mice. Additional injection of normal thymocytes into B cell mice which had been transferred with the Lyt-1 dull T cells resulted in complete prevention of thyroiditis induction. Mature thymocytes were responsible for this regulatory function and such regulatory cell activity was also found in peripheral lymphoid cells such as spleen cells. These regulatory cells exerted their capacity to prevent thyroiditis in cell dose-dependent and injection timing-dependent manners; thyroiditis was prevented when they were injected in cell doses of greater than 1.5 x 10(7)/mouse and before the initiation of the thyroiditis lesion. Most interestingly, the phenotypes of regulatory cells were Thy-1+ and L3T4+. Since the thyroiditis-inducing Lyt-1 dull T cells has previously been shown to be of L3T4+, these results indicate that there exist functionally heterogeneous subsets in an L3T4+ T cell population and that some L3T4+ T cells function as regulatory cells to prevent the activation of thyroiditis-inducing L3T4+ T cells co-existing in the normal lymphoid cell population.

Animals↗
PubMed1990

Transposon insertion mutagenesis of a genetic region encoding serum resistance in an 80 kb plasmid of Salmonella dublin.

Using transposon insertion mutagenesis with Tn1 or Tn5, we obtained Salmonella dublin mutant strains that showed either diminished serum resistance (five mutants) or diminished mouse lethality (two mutants). Detailed restriction cleavage analysis to determine the single sites of transposon insertion in an 80 kb plasmid (pTE800) indicated that a region for serum resistance was located within a 3.0 kb region of the SalI cleavage fragment 5 and the HindIII fragment 2, while the region for mouse lethality was within a 6.0 kb region of the SalI fragment 2 and the HindIII fragment 1. When the Tn1-containing SalI fragment 5 was reconverted, by homologous recombination, to the original SalI fragment 5 (9.6 kb), serum resistance was recovered to the same level as that of a parent strain 52401. Moreover, the change in the serum resistance correlated with changes in the neutral sugar composition of the LPS. The mutation in the plasmid in strain TE4-55 that gave diminished mouse lethality was also reversed by recombination with the cloned SalI fragment 2 (15.0 kb), with concomitant recovery of mouse lethality. These results indicate that the genetic region for serum resistance is different from that for mouse lethality, and that the gene for serum resistance is closely involved with the expression of the neutral sugar composition of the LPS of S. dublin.

Animals↗
PubMed1990

Stimulatory effects of bombesin on plasma trypsin release and exocrine pancreatic secretion in dogs.

We examined the effect of bombesin on plasma trypsin release and exocrine pancreatic secretion in dogs. Bombesin significantly increased plasma immunoreactive trypsin (IRT). Atropine significantly inhibited the response of plasma IRT to bombesin. Pancreatic trypsin secretion was also increased by bombesin, as well as bicarbonate and protein outputs. Atropine failed to inhibit pancreatic trypsin secretion. In conclusion, bombesin has a stimulatory effect on plasma trypsin release mediated by a cholinergic mechanism and different from pancreatic secretion.

Amylases↗
PubMed1990

SCID (severe combined immunodeficiency) mice as a new system to investigate metastasis of human tumors.

In severe combined immunodeficiency (scid) mice which are deficient in T and B cell functions, human yolk sac tumor (YST-2) grew rapidly to enormous sizes in all of the animals after both subcutaneous and intraperitoneal transplantation, while only half of the subcutaneous and none of the intraperitoneal transplants were accepted in usual athymic nude mice. Furthermore, transplanted tumors metastasized spontaneously to distant organs such as lung, liver, kidney, pancreas, and spleen in scid mice, while metastases were not found in athymic nude mice. Similar results were observed in scid mice and scid-nude (streaker) double mutant mice with human classic (typical) seminoma which has been neither transplantable nor metastatic in athymic nude mice. Thus, scid mice provide an invaluable experimental system to investigate the mechanism of metastasis which is the most important and life-threatening problem in cancer patients.

Animals↗
PubMed1989

Cytotoxic T lymphocyte unresponsiveness induced by prolonged treatment with immobilized anti-CD3 antibody. Association of impairment of cytolytic activity with temporary depletion of intracellular protein kinase C.

In our study we investigated the effect of pretreatment of bulk CTL and CTL clones with immobilized anti-CD3 antibody (Ab) or PMA. Primary CTL and CTL clones were cultured in dishes coated with anti-CD3 Ab or in medium containing PMA (5 nM) and assayed for Ag-specific or Ag-nonspecific "redirected" cytolysis using FcR+ P815 cells as targets. Cytotoxic activity of bulk CTL and five of six CTL clones tested in this study were inhibited by prolonged (longer than 6 h) pretreatment with immobilized anti-CD3 Ab or PMA, whereas proliferation of CTL clones or expression of surface CD3 molecules were not. The intracellular granule enzyme (N-alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester esterase) activity of CTL clones was not reduced under these suppressive conditions, indicating that the incompetence of CTL is not merely due to depletion of cytolytic granules by chronic stimulation. The suppressed cytotoxicity could be recovered by culturing CTL without perturbation of CD3 molecules for 24 h. In one exceptional clone, BM10-37, pretreatment with immobilized anti-CD3 Ab or PMA did not suppress the cytotoxic activity. Immunostaining of intracellular protein kinase C (PKC) revealed that PKC was depleted after prolonged treatment with immobilized anti-CD3 Ab or PMA in those susceptible CTL clones but not in the resistant BM10-37. These findings lead us to conclude that prolonged stimulation of CD3 of CTL results in depletion of PKC and that PKC may be essential for signal transduction to deliver a lethal hit to the target cells.

Animals↗
PubMed1989

Central pressor actions of neurokinin B: increases in neurokinin B contents in discrete nuclei in spontaneously hypertensive rats.

The regional distributions of neurokinin B-like immunoreactivity and substance P-like immunoreactivity in the central nervous system in spontaneously hypertensive rats (SHRs) and normotensive Wistar Kyoto rats (WKYs) were examined. The distribution of neurokinin B-like immunoreactivity in WKYs was not exactly the same as that of substance P-like immunoreactivity. The neurokinin B-like immunoreactivity contents of the supraoptic nucleus of the hypothalamus and the caudal part of the nucleus tractus solitarii were higher in SHRs than in WKYs. Injections of selective neurokinin B receptor peptides, senktide (suc-[Asp6,Me-Phe8]-substance P6-11) and [Pro7]-neurokinin B, into the lateral brain ventricle of the normotensive rats caused dose-dependent increases in the blood pressure, and blockade of peripheral vascular vasopressin receptors reduced these pressor responses, but did not affect the substance P-induced pressor response. These findings suggest that the novel tachykinin peptide, neurokinin B has an important role in central pressor action in rats.

Animals↗
PubMed1989

Tolerance induction of allo-class II H-2 antigen-reactive L3T4+ helper T cells and prolonged survival of the corresponding class II H-2-disparate skin graft.

The present study investigates the effects of i.v. presensitization with class II H-2-disparate allogeneic cells on various L3T4+ T cell functions including the capability of rejecting the corresponding allogeneic skin graft. C57BL/6 (B6) mice were i.v. presensitized with class II H-2 disparate B6-C-H-2bm12 (bm12) spleen cells. Such presensitization did not affect the bm12-specific L3T4+ T cell-mediated proliferative and interleukin 2 (IL-2)-producing capacities. A single cell suspension of (B6 x bm12)F1 spleen cells was depleted of APC by two round-passages over Sephadex G-10 columns. This APC-depleted fraction of (B6 x bm12)F1 cells failed to stimulate B6 responding cells in mixed lymphocyte reactions (MLR). The addition of recombinant IL-1 to the MLR restored anti-bm12 MLR responses, indicating that APC-depleted (B6 x bm12)F1 cells bear bm12 alloantigens but are unable to stimulate B6 anti-bm12 L3T4+ T cells. A single i.v. administration of APC-depleted (B6 x bm12)F1 cells into B6 mice resulted in almost complete abrogation of the capacity of recipient B6 lymphoid cells to give anti-bm12 MLR and IL2 production. This suppression was bm12 alloantigen-specific and attributed to the elimination or functional impairment of anti-bm12 T cell clones rather than the induction of suppressor cells. The tolerance was also observed in graft-rejection responses. The strikingly prolonged survival of bm12 skin grafts was produced when grafts were implanted into B6 mice which had been presensitized with APC-depleted, but not with untreated (B6 x bm12)F1 spleen cells. These results indicate that allo-class II H-2 antigen-reactive L3T4+ T cells are rendered tolerant by i.v. presensitization with APC-depleted fraction of the corresponding allogeneic cells.

Animals↗
PubMed1989

Tolerance induction of allo-class I H-2 antigen-reactive Lyt-2+ helper T cells and prolonged survival of the corresponding class I H-2-disparate skin graft.

C57BL/6 (B6) mice were i.v. presensitized with class I H-2-disparate B6-C-H-2bm1 (bm1) spleen cells. Such presensitization resulted in almost complete abrogation of bm1-specific Lyt-2+ T cell-mediated proliferative and IL-2-producing capacities as measured by MLC of lymphoid cells from presensitized B6 mice with stimulating bm1 cells. In contrast, comparable magnitude of CTL responses was generated in bulk cultures from presensitized B6 lymphoid cells to that obtained in unpresensitized B6 responding cultures. These differential influences of Lyt-2+ T cell functions were also demonstrated by limiting dilution assays; frequencies of proliferative and IL-2-producing T cell precursors were as low as undetectable in presensitized B6 lymphoid cells, whereas an appreciable frequency of CTL precursors in a portion of the same lymphoid cells was observed. When bm1 skin grafting was performed in B6 mice i.v. presensitized with bm1 cells, the strikingly prolonged survival of bm1 skin grafts was observed. It was also demonstrated that the bm1 skin graft-bearing B6 mice which had been presensitized with bm1 cells not only exhibited a continuing suppressive state of bm1-specific helper (proliferative and IL-2-producing) function but also failed to generate anti-bm1 CTL responses. These results indicate that 1) i.v. presensitization with class I H-2 alloantigens results in selective tolerance of Lyt-2+ Th cells which is adequate for inducing prolonged graft survival, 2) the induction of complete abrogation of CTL potential is not absolute requirement for the prolongation of graft survival, and 3) residual CTL potential is attenuated after grafting so far as Th cells are rendered tolerant.

Animals↗
PubMed1989

Cardiovascular roles of tachykinin peptides in the nucleus tractus solitarii of rats.

Unilateral removal of the afferent fibers of the IXth and Xth cranial nerve (nodose ganglionectomy) caused significant decrease in the content of substance P-like immunoreactivity (SP-LI) and neurokinin A-like immunoreactivity (NKA-LI) in the nucleus tractus solitarii (NTS) of rats. Microinjection of SP (1 ng) or NKA (10-100 ng) into the NTS caused prompt, transient hypotension and bradycardia, suggesting that SP and NKA may be neurotransmitters of the baroreceptor reflex in the NTS. NKB-like immunoreactivity (NKB-LI) was also detected in the NTS of rats by radioimmunoassay, but its content in the NTS was not affected by unilateral nodose ganglionectomy. The microinjection of 1-10 ng of suc-[Asp5, Me-Phe8]-SP(6-11) (senktide, a selective neurokinin B receptor peptide) into the NTS caused long-lasting hypertension and tachycardia. These results indicate that NKB may also be a neuromodulator on cardiovascular responses in the NTS.

Animals↗