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K Inaba

Publications and source records attributed to K Inaba.

At least 73 records · Page 4Linked to original sources
PubMed1989

Platelet vasopressin receptor in patients with chronic renal failure.

The vasopressin binding to intact platelet from patients with chronic renal failure (CRF) was investigated in relation to the abnormalities in platelet aggregation. The immunoreactive arginine vasopressin (AVP) in platelet-free plasma (PFP) but not in platelets was significantly higher in non-dialyzed patients with CRF than in normal subjects. Binding studies using [3H]AVP demonstrated a decreased number of binding sites (Bmax) on platelets from patients with CRF compared to normal controls with no significant difference in affinity (Ka). A significant diminution of the maximal percentage aggregation with AVP was found in patients with CRF. An inverse relation between Bmax and the PFP AVP levels and a highly significant relation between Bmax and the maximal percentage aggregation with AVP in patients with CRF and normal controls were observed. At 4 weeks after the introduction of hemodialysis in patients with CRF, the PFP AVP levels decreased and Bmax increased significantly, and the maximal percentage aggregation tended to increase. The present findings suggest that a reduced number of AVP receptors on platelets might account for decreased platelet aggregation with AVP, and the elevated plasma AVP levels might induce a down-regulation of the AVP receptor number on platelets in patients with CRF.

Adult↗
PubMed1988

Macrophages phagocytose thymic lymphocytes with productively rearranged T cell receptor alpha and beta genes.

The thymus gland is important for the formation of competent T lymphocytes. However, there is long-standing evidence that greater than 95% of newly formed thymocytes do not emigrate to peripheral lymphoid tissues but instead die locally. We have identified a rapid and selective pathway for thymocyte turnover in vitro. The mechanism entails binding, uptake, and digestion by macrophages. The susceptible cells are a subpopulation of double-positive thymocytes. These thymocytes can be enriched by virtue of their high buoyant density in Percoll and prove to have low levels of surface CD3 and little or no surface TCR. However TCR-alpha and -beta genes have undergone rearrangement, and full length alpha and beta transcripts are abundant. Therefore many double-positive cells rearrange and express TCR genes but do not have normal levels of TCR on the cell surface. We propose that thymocytes that undergo high turnover in situ are unable to form receptors that can be selected by MHC molecules in the thymus, and that these cells are recognized and cleared by the macrophage.

Gene Rearrangement, T-Lymphocyte↗
PubMed1988

Neuraminidase-treated macrophages stimulate allogenic CD8+ T cells in the presence of exogenous interleukin 2.

Prior work has shown that purified, resident, and inflammatory peritoneal macrophages are weak stimulators of the allogeneic MLR. We have identified conditions whereby thioglycollate-elicited macrophages become stimulatory, but primarily for the CD8+ T cell subset. The conditions were to treat the macrophages with neuraminidase and to supplement the MLR with rIL-2. These treatments together led to proliferative and cytotoxic responses by isolated CD8+ but not CD4+ T cells. Likewise when MHC-congenic strains were evaluated, an MLR was observed across isolated class I but not class II MHC barriers. Pretreatment of the macrophages with IFN-gamma further enhanced expression of class I MHC products and stimulatory activity, but did not seem essential. While these treatments did not render macrophages stimulatory for an MLR in purified CD4+ cells, blastogenesis of CD4+ cells was observed when the MLR involved bulk T cells. Small allogeneic B lymphocytes behaved similarly to macrophages, in the pretreatment with neuraminidase and supplementation with rIL-2 rendered B cells stimulatory for allogeneic, enriched, CD8+, but not CD4+, T cells. Spleen adherent cells, which are mixtures of macrophages and dendritic cells, stimulated both CD4+ and CD8+ T cells, and neither neuraminidase nor exogenous IL-2 was required. We think that these data suggest that most macrophages and small B cells lack three important functions of dendritic cells: a T cell-binding function that can be remedied by neuraminidase treatment, a T cell growth factor-inducing function that can be bypassed with exogenous IL-2, and an IL-2 responsiveness function that is required by CD4+ lymphocytes.

Animals↗
PubMed1988

Lymphokine production by murine T cells in the mixed leukocyte reaction.

Although the production of B cell stimulatory factors by cell lines and hybridomas is well established, production of specific lymphokines by normal T cells in response to antigen stimulation has not been analyzed. We have used bioassays and neutralizing mAbs to demonstrate that IL-2, IL-4, and B cell growth factors (BCGF) are produced during primary and secondary MLRs. IL-2 is detected in the first 12 h of both types of MLR. IL-4 and BCGF appear at 24-48 h in the conditioned medium of the primary MLR, and peak by 12 h in the secondary MLR. The amount of IL-4 in the primary response reaches a level that is 10% of that detected in the secondary. In contrast, BCGF production steadily increases over time in the primary MLR, and maximal production is equivalent to that made in the secondary response. Allogeneic dendritic cells and anti-Ig-activated B blasts both stimulated lymphokine production in the primary MLR, whereas small B cells were weak. In the secondary MLR, all three cell populations stimulated the production of IL-2, IL-4, and BCGF. Therefore, the release of several defined B cell stimulating factors can be detected in the conditioned media of responding primary T lymphocytes.

Animals↗
PubMed1988

Unusual phenotype of B cells in the thymus of normal mice.

A small number of B cells are found in the thymus of normal mice. A population of B lymphocytes could be enriched to greater than 90% purity by isolating a low-density fraction on Percoll density gradients and then depleting T cells with a mixture of anti-Thy-1, CD4, and CD8 mAbs and complement. Enrichment was monitored by surface Ig staining and by functional studies (responsiveness to LPS, and to anti-mu plus IL-4). When the phenotype of these B cells was studied by flow cytometry, 60-80% had the phenotype Ly-1+ (CD5), Ia+, B220low (CD45R), and Mac-1+ (CD 11b). In contrast, splenic B cells lacked CD5 and CD11b and expressed higher levels of B220 and Ia antigens. These results indicate that most thymic B cells have the phenotype of the Ly-1 B cell subset, which was identified previously as a trace subpopulation in some peripheral tissues and is thought to play a role in autoantibody formation.

Animals↗
PubMed1988

Effect of recombinant human interferon-alpha A/D on in vivo murine tumor cell growth.

We investigated the effect of human recombinant interferon-alpha A/D A/D-IFN), which is known to delay the growth of murine tumor cells, on the growth of S1 and R1 subline cells of murine Meth A fibrosarcoma in the peritoneal cavity of mice. In vitro growth of S1 cells was sensitive to, and that of R1 cells was resistant to, the direct effect of A/D-IFN, as with murine natural IFN-alpha/beta, which was used originally to isolate these sublines. In vivo, however, the growth of not only S1 cells but also R1 cells was suppressed by the administration of A/D-IFN, and the survival time of tumor-bearing mice was prolonged. Although A/D-IFN had a direct effect on S1 cells in vivo, R1 cells were susceptible only to the indirect effect via the host cells. Macrophages (M phi) harvested from the peritoneal cavity of A/D-IFN-treated mice bearing ascitic R1 cells were very effective in suppressing the in vitro growth of R1 cells; those from non-R1-bearing A/D-IFN-treated mice were less effective. The results of in vitro experiments indicate that M phi are very probably activated by the synergism of A/D-IFN and M phi diameter-activating factor(s) produced by lymphoid cells in tumor-bearing mice.

Animals↗
PubMed1988

The function of Ia+ dendritic cells and Ia- dendritic cell precursors in thymocyte mitogenesis to lectin and lectin plus interleukin 1.

The response of thymocytes to lectin is a standard tissue culture model for identifying cytokines such as IL-1 that are required for thymocyte mitogenesis. To study accessory cell requirements for these responses, it was necessary to deplete endogenous accessory cells with two techniques: anti-Ia and complement, and passage over nylon wool. Proliferation to Con A was then restored with 0.1-0.3% exogenous splenic dendritic cells, or 30-fold higher levels of peritoneal macrophages. The "costimulatory" action of IL-1, whereby responses to lectin were enhanced 3-10-fold, required the presence of dendritic cells. This effect of IL-1 could be reproduced by culturing the dendritic cells for 12 h in 1 U/ml human or murine rIL-1 alpha before addition to the thymocyte proliferation assay. The function of IL-1-treated dendritic cells was not blocked by a neutralizing anti-IL-1 antibody. The endogenous population of thymic accessory cells was partially characterized. A trace (0.1-0.3%) fraction of Ia+, Ig-, plastic nonadherent dendritic cells was visualized and enriched to a level of 1-10% by depleting CD4+,CD8+, and Ig+ lymphocytes. When this double-negative population was cultured with IL-1 and washed, the treated thymic dendritic cells were 10-fold more active as accessory cells. When the CD4-,CD8-, Ig- populations were depleted of dendritic cells with anti-Ia and complement, the subsequent addition of IL-1 had a second effect. Ia+ dendritic cells redeveloped over a 2-d interval, and they exhibited the same properties as resident dendritic cells in thymus and spleen. The majority were lysed by 33D1 anti-dendritic cell mAb and complement, lacked Fc receptors, and acted as powerful stimulators of the MLR and Con A mitogenesis. The development of dendritic cells did not occur with IL-2, -3, -4 or granulocyte/macrophage colony-stimulating factor or in nylon-nonadherent populations. The IL-1-dependent, Ia- precursor was not detectable in bone marrow. These results begin to analyze the endogenous accessory function of the thymus in culture. Dendritic cells actively stimulate thymocyte mitogenesis. The mitogenic action of IL-1 involves effects on resident Ia+ dendritic cells as well as a new population of thymic, Ia- precursors.

Animals↗
PubMed1988

The binding of antigen presenting cells to T lymphocytes.

In the introduction, we asked how MHC molecules on the surfaces of APC make contact with antigen-specific receptors on the surfaces of T cells. We have reviewed two models in which antigen-specific contacts occur with primary leukocyte populations in vitro. One system involves resting T cells; the other sensitized T lymphoblasts. At the onset of a primary immune response, dendritic cells seem critical for binding and activating both CD4+ and CD8+ subsets. Given the current evidence, we suggest that dendritic cells literally find the right T cell clone, and not vice versa, and that dendritic cells do so by first binding and surveying T cells by an antigen-independent mechanism. In the efferent limb of immunity, other types of APC including B cells and macrophages bind and stimulate freshly sensitized T lymphoblasts. Freshly isolated epidermal Langerhans cells do not cluster T cells by an antigen-independent mechanism but acquire this capacity during epidermal suspension culture. Under the control of GM-CSF, the Langerhans cell becomes a powerful accessory cell for the primary or sensitization limb of T-dependent immune responses like the MLR and primary antibody response. Isolated lymphoid dendritic cells have many features in common with interdigitating cells in lymphoid T areas, and may be related to some of the irregularly-shaped Ia+ cells in certain epithelia and interstitial regions. Contact with dendritic cells may be important in both central and peripheral pathways of T cell sensitization in situ.

Animals↗
PubMed1988

Down-regulation of macrophage Ia mRNA expression by interferon (IFN)-alpha and IFN-beta mediated by de novo synthesized protein.

We investigated the regulation of class I and class II major histocompatibility complex (MHC) antigen expression of murine peritoneal macrophages (M phi) by interferons (IFNs) at the mRNA level. Enhancement of class I antigen expression by IFNs (IFN-alpha, beta, and gamma), induction of class II antigen expression by IFN-gamma, and inhibition of class II antigen expression by IFN-alpha or IFN-beta all corresponded to steady-state levels of these MHC-specific mRNAs. Cycloheximide (CHX), a protein synthesis inhibitor, was used to elucidate whether IFN regulation of MHC mRNA expression depends on the newly synthesized proteins. CHX concentration was carefully chosen so that M phi viability was not decreased, total protein synthesis was considerably but not completely inhibited, and suppression of surface class II expression was virtually perfect. Under these conditions CHX did not affect the levels of either class I or class II mRNA, but it prevented IFN-beta from interfering with class II mRNA induction by IFN-gamma. These results indicate that the augmentation of induction and/or accumulation of MHC mRNA by IFNs is not dependent on the de novo synthesis of protein, but the down-regulation of class II mRNA level by IFN-beta is mediated by some newly synthesized protein(s).

Animals↗
PubMed1988

Ontogeny of 'macrophage' function. VI. Down-regulation for Ia-expression of newborn mouse macrophages by endogenous beta-interferon.

Peritoneal exudate macrophages (M phi) of newborn mice (NB-M phi) were apparently almost incapable of expressing Ia antigen even if stimulated by IFN-gamma. No significant difference was observed in the number and the affinity of receptors for IFN-gamma between NB-M phi and M phi of adult mice (Ad-M phi). Addition of indomethacin, a prostaglandin synthesis inhibitor, was ineffective in enhancing the Ia-expression of NB-M phi. Responsiveness of NB-M phi to IFN-gamma, however, was disclosed by the addition to the culture of anti-IFN-beta or anti-IFN-alpha/beta, but not anti-IFN-alpha antibody. Responsiveness of NB-M phi to IFN-gamma was not improved by the depletion of fibroblasts from NB-M phi populations. These results strongly argue that Ia-expression of NB-M phi, which is otherwise to be induced by IFN-gamma, is suppressed by IFN-beta derived from NB-M phi themselves.

Animals↗
PubMed1988

Differentiation of an interleukin 3-dependent precursor B-cell clone into immunoglobulin-producing cells in vitro.

Precursors to B-cell lines with immunoglobulin genes in the germ-line context have been shown to be capable of generating mature B cells in vivo. We report here that an interleukin 3-dependent precursor B-cell line, LyD9, differentiated in vitro into mature B cells, producing IgM and IgG by coculture with bone marrow accessory (or stroma) cells or with dendritic cells and T cells. Up to 50% of IgM-positive cells, but no Thy-1-positive cells, appeared after the 7- to 10-day coculture. Induced LyD9 cells underwent heterogenous immunoglobulin gene rearrangement and synthesized mRNAs encoding immunoglobulin mu, gamma, and kappa chains. However, these cells did not show any rearrangement of genes encoding the alpha and beta chains of the T-cell receptor. The induction of differentiation by coculture with bone marrow stroma cells was blocked by anti-lymphocyte function-associated antigen 1 or anti-interleukin 4 antibody. These systems are useful for molecular biological studies on regulation of differentiation of bone marrow-derived cells into the B-cell lineage.

Animals↗
PubMed1988

Wheat germ agglutinin-positive cells in a stem cell-enriched fraction of mouse bone marrow have potent natural suppressor activity.

In the present study we have characterized natural suppressor (NS) cells, which nonspecifically suppress mitogen responses and mixed-lymphocyte reaction. The strongest NS activity was found in a fraction of relatively low-density cells (1.063 less than p less than 1.075) obtained by equilibrium density centrifugation. Further purification and characterization of these NS cells by using a fluorescence-activated cell sorter indicated that wheat germ agglutinin (WGA)-positive cells have potent NS activity, whereas WGA-negative cells have no NS activity. Spleen colony-forming unit (CFU-S) assays demonstrated a significant correlation between the number of CFU-S cells and the NS activity in the bone marrow. However, WGA-positive cells obtained from the bone marrow of animals treated with 5-fluorouracil, which cells in turn were exposed to 5-fluorouracil, showed a marked reduction in NS activity. These results suggest that the pluripotent stem cells have NS activity when the cells are in the cycling phase but not when the cells are in the G0 phase. It seems possible that apparently primitive cells play an important role in down-regulation of immune responses.

Animals↗
PubMed1988

Platelet vasopressin receptor in essential hypertension.

The specific vasopressin receptor of V1 vascular subtype, which mediates platelet aggregation, has been found on human platelets. We investigated the binding characteristics using tritiated arginine vasopressin [3H]-AVP and platelet aggregation with AVP turbidometrically in normal subjects, patients with WHO class II essential hypertension and patients with malignant-phase hypertension. In essential hypertensives Bmax was significantly higher than that in normal subjects, but there were no differences in affinity and the maximal percentage aggregation between them. In malignant-phase hypertensives Bmax and maximal percentage aggregation were significantly lower than those in normals and essential hypertensives, although there was no difference in the affinity between them. With radio-immunoassay, the mean platelet-free plasma AVP level was significantly higher in malignant-phase hypertensives than those in normals and essential hypertensives, whereas there was no difference in mean platelet AVP levels between them. In essential hypertensives Bmax and maximal percentage aggregation did not change, but in malignant-phase hypertensives Bmax increased significantly and maximal percentage aggregation tended to normalize after treatment.

Arginine Vasopressin↗
PubMed1988

Immortalization of murine leukocytes by oncogenes. II. Phenotypic characterization of transformants immortalized by v-src or Ha-ras oncogenes: expression of B220, a B-cell lineage specific antigen.

In the course of study to obtain murine dendritic cell lines using oncogenic retroviruses, we have established several immortalized cell lines with characteristics different from those of dendritic cells. The transformants were mainly round nonadherent cells, capable of growing in soft agar, and negative for nonspecific esterase activity. Profiles of cell surface antigens were examined by indirect immunofluorescence technique. The cell lines were positive for Fc receptor (2.4G2), J11d (J11d.2), and B220 (RA3-3A1/6.1) antigens and negative (or dull positive in small percentages) for Ia (M5/144.15.2), IL-2 receptor (3C7), Thy-1 (B5-5), Mac-1 (M1/70.-15.11.5), and macrophage (F4/80) antigens. They were negative for both surface and cytoplasmic immunoglobulins. Several clones were established from these transformant cell lines and cell surface antigens were examined. Antigenic profiles of these clones were very similar to those of the parental cell lines. Some of these clones, however, seemed to increase their Ia antigen expression. The results suggest that the transformants originated from early B-lineage cells.

Animals↗
PubMed1988

Characterization of human platelet vasopressin receptor and the relation between vasopressin-induced platelet aggregation and vasopressin binding to platelets.

Immunoreactive AVP was found to be much higher in platelets than in platelet-free plasma (PFP) in normal subjects (12.8 +/- 6.3 versus 1.7 +/- 0.8 fmol/ml). AVP levels in PFP were appreciably elevated in parallel with the elevation of plasma osmolality induced by the acute osmotic stimulation, while the AVP levels in platelets did not change before and after the stimulation. Binding studies on intact platelets demonstrated specific binding sites for [3H]AVP. The specific binding was time, temperature and concentration-dependent, saturable and reversible, with the maximal binding capacity (Bmax) of 169.9 +/- 14.4 sites/platelet and affinity of 4.84 +/- 1.15 x 10(8)M-1. The affinity constants for unlabelled AVP, lysine vasopressin (LVP), oxytocin (OT) and dDAVP were 9.0, 8.5, 7.4 and 6.6, respectively, and the inhibition constant for d(CH2)5Tyr(Me)AVP (V1-antagonist) was 7.7. There was a highly significant correlation between the affinity constants of AVP analogues and their relative vasopressor activities in vivo, whereas no such correlation was found between the affinity constants and antidiuretic activities. AVP caused platelet aggregation with the maximal aggregation of 48.0 +/- 25.1% at 230 nM of AVP. A significant correlation was observed between the maximal percentage aggregation and Bmax of [3H]AVP to intact platelets. These results suggest that the platelet vasopressin receptor belongs to the V1 vascular subtype and mediates platelet aggregation.

Adult↗
PubMed1988

The sensitization phase of T-cell-mediated immunity.

Many cell-mediated immune responses appear to develop in two phases: A sensitization phase in which unprimed or memory T cells interact with dendritic cells to become active lymphoblasts, and an effector phase in which the T lymphoblasts and other presenting cells interact to eliminate the antigen. Antigen presentation is essential to both phases. Here we review several features that are pertinent to the special sensitization role of dendritic cells. First, dendritic cells from lymphoid tissues, blood, and lymph (lymphoid dendritic cells) express very high levels of class I and II MHC products, and these levels cannot be increased by exposure to cytokines such as immune interferon. Second, dendritic cells efficiently cluster antigen-specific T cells during primary responses. Other presenting cells, like macrophages and B lymphocytes, do not form clusters but do bind to sensitized T lymphoblasts. Dendritic-T-cell binding is not inhibited by mAb to CD4 and LFA-1 antigens. It is suggested that a dendritic-cell-specific molecule is required. Third, it is not yet clear if dendritic cells make a "lymphocyte activating factor." However, IL-1 is not produced, even when dendritic cells are in contact with responding T cells. Fourth, dendritic cells have the capacity to migrate from the tissues and move to T-dependent areas. Epidermal Langerhans cells represent a reservoir of tissue dendritic cells but seem to be immunologically immature. The viability and accessory function of the Langerhans cell greatly depend on a single cytokine, granulocyte-macrophage colony stimulating factor (GM-CSF), leading to the proposal that GM-CSF is critical in mobilizing active dendritic cells at the onset of a cell-mediated immune response.

Animals↗