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Biomedical subjects

H Kikutani

Publications and source records attributed to H Kikutani.

At least 55 records · Page 3Linked to original sources
PubMed1997

Cognate T cell help for CD40-deficient B cells induces c-myc RNA expression, but DNA synthesis requires an additional signal through surface Ig.

To investigate the role of CD40 ligand in the delivery of help to B cells, we examined the Ag-specific interaction of B cells from CD40-deficient mice with a Th2 cell line in vitro. Small resting B cells from normal mice are stimulated to synthesize DNA when they present monovalent Ag (rabbit Fab anti-Ig) to a rabbit Ig-specific Th cell line. This response, which is independent of a signal through the B cell Ag receptor (sIg), is nearly absent in B cells from CD40-deficient mice. The CD40-deficient B cells are not defective in Ag presentation because they induce T cell IL-4 synthesis as well as normal B cells. Also, CD40-deficient B cells respond to T cell help with DNA synthesis almost as well as normal B cells if an additional signal is provided through sIg. In conjunction with a sIg signal, cell contact with helper T cells induces DNA synthesis more effectively than soluble cytokines. CD40-independent T cell help can also be measured as an early increase in c-myc mRNA levels in CD40-deficient B cells presenting Ag to helper T cells, although the levels of c-myc RNA expression are lower than those in normal B cells. However, c-myc RNA induced by noncognate interaction with anti-CD3-activated T cells is completely CD40 dependent. We conclude that early growth signals from activated Th cells are received by CD40-/- B cells, but that CD40 and/or sIg signals are required for efficient induction of DNA synthesis.

Animals↗
PubMed1997

Genetic control of diabetes progression.

Autoimmune diabetes in both the human and the nonobese diabetic mouse has elaborate genetics; in the latter case, the disease is influenced by at least 15-20 loci. We anticipated that the genetics would be simpler in the BDC2.5 T cell receptor transgenic mouse model of diabetes, wherein many T cells express a particular diabetogenic specificity. Initiation of insulitis in this model was the same on the two genetic backgrounds analyzed, but the kinetics and penetrance of diabetes were strikingly different, permitting us to focus on genetic influences during a defined window of disease progression. The differences correlated with variations in five genomic intervals, certain ones of which have been previously implicated in susceptibility to autoimmune disease. This reductionist approach indeed simplified the analysis of diabetes susceptibility loci.

Animals↗
PubMed1997

CD23 deficient mice develop allergic airway hyperresponsiveness following sensitization with ovalbumin.

The low affinity receptor for IgE (CD23) is reported to regulate immune and inflammatory events and as a result, it may have a role in the development of allergic airway inflammation and hyperresponsiveness (AHR). To test this hypothesis CD23-deficient mice were studied following different modes of allergic sensitization. Mice were actively sensitized either intraperitoneally with ovalbumin (OA)/alum or via the airways (10 days exposure to OA aerosol with no adjuvant). Passive sensitization was performed by intravenous injections of OA-specific IgE. Airway responsiveness, serum IgE and IgG levels were assessed together with airway inflammation. Passive sensitization followed by airway challenges resulted in increased OA-specific lgG and IgE in the serum of wild-type mice only, while both the CD23+/+ and CD23-/- groups developed tracheal smooth muscle hyperresponsiveness to electrical field stimulation, indicating that IgE/CD23-mediated immune functions may not be necessary for the development of allergic changes. Active sensitization of both CD23-/- and CD23+/+ mice resulted in increased serum levels of OA-specific IgE and lgG, airway eosinophilia and significant AHR when compared with nonsensitized mice. The genetic deficiency of CD23-/- mice not only failed to prevent but was associated with a significant increase of these responses. These results indicate that CD23 may not be essential for the development of allergen-induced AHR and further, that its presence may have some inhibitory effects on the allergic response.

Allergens↗
PubMed1996

Prevention of adoptively transferred diabetes in nonobese diabetic mice with IL-10-transduced islet-specific Th1 lymphocytes. A gene therapy model for autoimmune diabetes.

Four pancreatic islet-specific CD4+ helper T (Th) 1 (Th1) clones and two Th1 clones transduced with an SRalpha promoter-linked murine IL-10 (mIL-10) cDNA of 2.0-6.0 x 10(6) cells were adoptively transferred to nonobese diabetic (NOD) mice at age 8 d. Cyclophosphamide (CY) was administered at age 37 d (plus CY), and the incidence of diabetes and the histological grade of insulitis were examined at age 47 d. After the adoptive transfer of IL-10-transduced Th1 cells, polymerase chain reaction (PCR) and reverse-transcription (RT)-PCR detected the neo gene and the retrovirus vector-mediated IL-10 mRNA in situ in recipient islets, respectively. RT-PCR detected the decrease of IFN-gamma mRNA relative to IL-10 mRNA in IL-10-transduced Th1 clones in vitro and also in recipient islets. All four wild type Th1 clones plus CY induced the insulitis grade of 2.75 and diabetes in 66% of recipient NOD mice. IL-10-transduced two Th1 clones plus CY induced periinsulitis with the grade of 1.43 and diabetes in 8.0%. The 1:1 mixture of wild type Th1 cells and IL-10-transduced Th1 cells plus CY induced periinsulitis with the grade of 1.85 and diabetes in 20%. The suppression of diabetes through decreasing IFN-gamma mRNA by the tissue-specific delivery of IL-10 to pancreatic islets with IL-10-transduced Th1 cells affords us the starting basis to develop the gene therapy for autoimmune diabetes.

Adoptive Transfer↗
PubMed1996

Induction of tolerance in murine autoimmune diabetes by transient blockade of leukocyte function-associated antigen-1/intercellular adhesion molecule-1 pathway.

The present study demonstrated that a short-term administration of mAbs against leukocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) at critical periods resulted in complete protection of autoimmune diabetes in non-obese diabetic (NOD) mice. When these mAbs were administered for only 6 days at 2 wk of age, neither diabetes nor insulitis was observed at 30 wk of age. It appears that the tolerance against beta cell Ag(s) was induced by this transient blockade of the LFA-1/ICAM-1 pathway. Protective suppressor activity was not enough to prevent diabetes because co-transfer of splenocytes from female NOD mice, which had received these mAbs at 2 wk of age, resulted in only a short delay of the diabetic onset caused by adoptive transfer of splenocytes from acutely diabetic NOD mice. Transfer of these splenocytes to young NOD mice could not also abrogate the spontaneous diabetes and insulitis. Furthermore, cyclophosphamide treatment could not abrogate the protection. When splenocytes from the treated NOD mice were transferred to NOD-SCID mice, none of the recipient mice developed significant insulitis and subsequent overt diabetes, suggesting the absence or the inactivation of diabetogenic effector T cells. However, splenic T cells from the insulitis-free NOD mice that had received the mAb treatment preserved proliferative responses to both islet cells and 65-kDa glutamic acid decarboxylase (GAD65) in vitro. These results suggest that a unique peripheral tolerance was induced by the transient blockade of the LFA-1/ICAM-1 pathway in an early age of NOD mice.

Adoptive Transfer↗
PubMed1996

Defects of B-cell lymphopoiesis and bone-marrow myelopoiesis in mice lacking the CXC chemokine PBSF/SDF-1.

The chemokines are a large family of small, structurally related cytokines. The physiological importance of most members of this family has yet to be elucidated, although some are inducible inflammatory mediators that determine leukocyte chemotaxis. Pre-B-cell growth-stimulating factor/stromal cell-derived factor-1 (PBSF/SDF-1) is a member of the CXC group of chemokines PBSF/SDF-1 stimulates proliferation of B-cell progenitors in vitro and is constitutively expressed in bone-marrow-derived stromal cells. Here we investigate the physiological roles of PBSF/SDF-1 by generating mutant mice with a targeted disruption of the gene encoding PBSF/SDF-1. We found that mice lacking PBSF/SDF-1 died perinatally and that although the numbers of B-cell progenitors in mutant embryos were severely reduced in fetal liver and bone marrow, myeloid progenitors were reduced only in the bone marrow but not in the fetal liver, indicating that PBSF/SDF-1 is responsible for B-cell lymphopoiesis and bone-marrow myelopoiesis. In addition, the mutants had a cardiac ventricular septal defect. Hence, we have shown that the chemokine PBSF/SDF-1 has several essential functions in development.

Animals↗
PubMed1996

CD40-CD40 ligand interactions are critical in T-B cooperation but not for other anti-viral CD4+ T cell functions.

CD40-CD40 ligand (CD40L) interaction is required for the generation of antibody responses to T-dependent antigens as well as for the development of germinal centers and memory B cells. The role of the CD40-CD40L interaction in the induction of antigen-specific. Th cells and in mediating Th cell effector functions other than cognate help for B cells is less well understood. Using CD40- and CD40L-deficient mice together with lymphocytic choriomeningitis virus and vesicular stomatitis virus as viral model antigens, this study corroborates earlier findings that no lg isotype switching of virus-specific antibodies was measurable upon infection of CD40- or CD40L-deficient mice. In contrast, in vivo induction of virus-specific CD4+ T cells measured by proliferation and cytokine secretion of primed virus-specific Th cells in vitro was not crucially dependent on the CD40-CD40L interaction. In addition, virus-specific Th cells primed in a CD40-deficient environment, adoptively transferred into CD40-competent recipients, were able to mediate lg isotype switch. Th-mediated effector functions distinct from and in addition to T-B collaboration were analyzed in CD40- and CD40L-deficient and normal mice: (a) local inflammatory reactions upon LCMV infection mediated by LCMV-specific Th cells were not dependent on a functional CD40-CD40L interaction, (b) cytokine-mediated protection by CD4+ T cells primed by vesicular stomatitis virus against a challenge infection with recombinant vaccinia virus expressing the glycoprotein of vesicular stomatitis virus was found to be equivalent in CD40L-deficient and normal mice. Thus, CD40-CD40L interaction plays a crucial role in T-B interactions for Th-dependent activation of B cells but not, or to a much lesser extent, in T cell activation, antigen-specific Th cell responses in vitro, and for interleukin-mediated Th cell effector functions in vivo.

Animals↗
PubMed1996

T-independent activation of B cells by vesicular stomatitis virus: no evidence for the need of a second signal.

Vesicular stomatitis virus (VSV) induces a T helper cell-independent IgM antibody response, whereas the IgG response is strictly T helper cell dependent. Since VSV induces B cells in complete absence of T helper cells, the question arises as to whether this induction occurs in the absence of a second signal or whether it depends upon an alternative or replacing signal 2. We therefore asked whether VSV has polyclonal B cell stimulator activity and/or whether B cell induction by VSV needs costimulation via complement or tumor necrosis factor (TNF) receptor or by natural killer (NK) cell activity. In vitro B cell proliferation assays and analysis of the in vivo antibody response in CD40-deficient mice excluded that VSV has properties of a polyclonal B cell stimulator. C3 depletion by cobra venom factor and application of anti-complement receptor antibodies showed that the T-independent IgM response was largely C3-independent except under very limiting antigen doses. Immunization of TNF receptor-deficient mice showed a normal anti-VSV IgM response, and in a cytotoxicity assay on YAC target cells there was no evidence of NK cell activation by VSV. Thus, VSV seems to induce B cells without polyclonal activation and/or C3, TNF, or NK cells functioning as a replacing second signal.

Animals↗
PubMed1996

B cell-B cell interaction through intercellular adhesion molecule-1 and lymphocyte functional antigen-1 regulates immunoglobulin E synthesis by B cells stimulated with interleukin-4 and anti-CD40 antibody.

IgE synthesis by purified human B cells is induced by two signals: a class switching factor, most commonly interleukin (IL)-4, and the engagement of CD40, which is activated through its interaction with CD40 ligand (CD40L) expressed on activated T cells. Thus, the combination of IL-4 and anti-CD40 monoclonal antibody (mAb) has been shown to stimulate IgE production in vitro by highly purified B cells. In this T cell-independent system, strong homotypic aggregation of B cells is observed prior to the production of IgE. Flow cytometric analysis and cell binding assays showed that the stimulation of purified B cells with anti-CD40 mAb plus IL-4 resulted in a striking increase of intercellular adhesion molecule (ICAM)-1(CD54) expression, an induction of CD43 and an avidity change of lymphocyte functional antigen (LFA)-1(CD11a/CD18), with little augmentation of CD18 expression. Addition of anti-ICAM-1 mAb caused an inhibition of homotypic aggregation but augmented IgE synthesis by B cells stimulated with anti-CD40 mAb and IL-4, although it did not affect B cell proliferation or IL-6 production by the B cells. Among the mAb against counter-receptors for ICAM-1 tested, anti-CD11a mAb suppressed IgE synthesis, while anti-CD18 mAb and anti-CD43 mAb had little effect. The enhancing or inhibitory effect of anti-ICAM-1 mAb or anti-CD11a mAb on IgE production was achieved by the increased or decreased expression of germline C epsilon transcripts by B cells stimulated with anti-CD40 mAb and IL-4. These results indicate that B cell-B cell interaction through ICAM-1 and one of its counter receptors, LFA-1, regulates IgE synthesis by modulating C epsilon germ-line transcription.

Antibodies, Monoclonal↗
PubMed1996

Protective role of CD40 in Leishmania major infection at two distinct phases of cell-mediated immunity.

CD40-deficient mice are susceptible to Leishmania major infection while their wild-type littermates can resolve the infection. Upon stimulation with L. major antigens, draining lymph node T cells of the mutant mice and the susceptible mice, BALB/c, secrete comparable amounts of IL-4. The mutant mice produce less IFN gamma than wild-type mice. The expression of IL-12 p40 mRNA was significantly lower in L. major antigen-stimulated cells of mutant mice than those of wild-type or BALB/c mice. In normal mice, engagement of CD40 activates macrophages to a leishmanicidal state in vitro in the presence of IFN gamma. The results suggest that the CD40-CD40 ligand interaction plays an important role in two critical steps of cell-mediated immunity to L. major infection: the generation of a Th1 response and activation of macrophages to a leishmanicidal state.

Animals↗
PubMed1996

Profound reduction of mature B cell numbers, reactivities and serum Ig levels in mice which simultaneously carry the XID and CD40 deficiency genes.

It has been known for some time that single mutant nude or CD40T mice have apparently normal numbers of cells in the precursor compartments of bone marrow and the mature B cell compartments of the periphery. X-linked immunodeficiency (XID) mice are deficient only in some of the sIgM+sIgD+ B cells. We have investigated further the contributions of the xid mutation, of the T cell deficiency of nude of the inability of CD40T cells to cooperate with T cells in the generation of the precursor and the mature B cell compartments in mice. Double mutant XID/nu and XID/CD40T mice have precursor B cell compartments that are no more deficient than the single mutant XID mice. However, the peripheral B cell compartments of both XID/mu and XID/CD40T are even more deficient than those of single mutant XID mice. While 10% of the peripheral B cells of wild-type or CD40T, one-third of XID and half of XID/nu mice turn over rapidly, as many as three-quarters of those in XID/CD40T are short-lived. Total numbers of sIgM+sIgD+ B cells in the spleen are at best 10-15% of normal mice at 6-8 weeks of age in XID, XID/nu and XID/CD40T mice. They remain that low at 3 months of age in XID/CD40T mice, while in XID mice these peripheral B cells slowly build up in numbers with age. As expected, double mutant XID/CD40T mice do not respond to the T-dependent antigen keyhole limpet hemocyanin. Only the responses to the T-independent type I antigen, TNP-lipopolysaccharide (LPS), appear to be normal. In vitro, their splenic B cells respond poorly to LPS or to IgM-specific antibody in either the absence or presence of cytokines. Most notably, serum IgM, IgG2b or IgG3 levels are severely depressed, while IgG1, IgG2a and IgA levels are < 10 micrograms/ml. These results suggest a model of mature B cell development in which the peripheral, mature B cell compartments are generated in two parallel, not tandemly organized pathways. They could be selected and/or stimulated at the transition from immature to mature B cells: in btk controlled or in CD40 controlled ways.

Animals↗
PubMed1996

Regulation of human papillomavirus transcription by the differentiation-dependent epithelial factor Epoc-1/skn-1a.

Human papillomavirus (HPV) early gene expression is closely linked to the differentiation status of infected epithelial cells. Typically, HPV type 16 (HPV16) or HPV18 E6 and E7 transcripts are only barely detectable within the undifferentiated basal cell layer, but their levels increase concomitantly with higher degrees of epithelial cell differentiation in suprabasal cells. A similar differentiation-dependent distribution of expression has been reported for the recently cloned epithelial cell specific transcription factor Epoc-1/skn-1a. We therefore examined whether Epoc-1/skn-1a may be directly involved in the activation of HPV E6/E7 transcription. Transient transfection studies showed that Epoc-1/skn-1a specifically stimulated the HPV16 and HPV18 E6/E7 promoters. Moreover, ectopically expressed Epoc-1/skn-1a was sufficient to stimulate HPV transcription also in nonepithelial cells. By deletion analyses, the Epoc-1/skn-1a-responsive element was mapped to the promoter-proximal portion of the HPV18 transcriptional control region. Footprint analyses and gel retardation assays demonstrated direct binding of Epoc-1/skn-1a to a hitherto uncharacterized site within this region. Mutation of the Epoc-1/skn-1a recognition site within the context of the complete HPV18 upstream regulatory region inhibited Epoc-1/skn-1a-mediated transactivation. These results show that Epoc-1/skn-1a can directly activate the E6/E7 promoter by binding to the viral transcriptional control region. Thus, Epoc-1/skn-1a may be involved in the differentiation-dependent regulation of HPV transcription.

Base Sequence↗
PubMed1995

CD40 ligand-transduced co-stimulation of T cells in the development of helper function.

Mice that lack either CD40 (expressed on B cells) or CD40 ligand (expressed on activated T cells) are able neither to make IgG, IgA or IgE antibody responses, nor to generate germinal centres (the sites of formation of memory B cells). It has been assumed that these lesions were the result of an absence of signals to B cells through CD40. Here we show that the failure to signal T cells through CD40 ligand is an important contributory cause. Administration of soluble CD40 in vivo to CD40 knockout mice, restoring the missing signal through CD40 ligand initiates germinal centre formation. Furthermore, T cells primed in the absence of CD40 (in CD40 knockout mice) are unable to help normal B cells to class switch or to form germinal centres (GC). These results indicate that co-stimulation of T cells through CD40 ligand causes their differentiation into cells that help B cells to make mature antibody responses and to generate memory populations.

Animals↗
PubMed1995

Homotypic aggregation of murine B lymphocytes is independent of CD23.

CD23 is a low-affinity receptor for IgE (Fc epsilon RII). Functions attributed to CD23 not involving IgE suggest that it interacts with ligands other than IgE. CD21 has recently been described as a counter ligand for CD23. A number of lines of evidence have implicated CD23 as an adhesion molecule in human B cells. We have investigated the role of CD23 in homotypic B cell aggregation in the mouse, using lipopolysaccharide plus interleukin-4-induced aggregation as a model system. In this system high levels of aggregation are accompanied by a massive up-regulation of CD23 expression. However, in contrast to what has been observed in human B cells, we find no evidence of a role for CD23 in homotypic adhesion of murine B cells.

Animals↗
PubMed1994

The absence of IgE antibody-mediated augmentation of immune responses in CD23-deficient mice.

The CD23 antigen, a low-affinity receptor for IgE (Fc epsilon RII), is a type II membrane-bound glycoprotein expressed on various cells, particularly mature B cells. A number of functions have been ascribed to CD23, including specific regulation of IgE production, IgE-mediated cytotoxicity and release of mediators, IgE-dependent antigen focusing, promotion of B-cell growth, prevention of germinal center B cells from apoptosis, proliferation of myeloid precursors, and maturation of early thymocytes. It is not clear whether these activities represent in vivo functions. To explore in vivo functions of CD23, we have produced CD23-deficient mice. These mice displayed normal lymphocyte differentiation and could mount normal antibody responses, including IgE responses upon immunization with T-dependent antigens and infection with Nippostrongyrus brasiliensis. Germinal center formation after immunization and in vitro proliferative response of B cells were not affected in mutant mice. However, antigen-specific IgE-mediated enhancement of antibody responses was severely impaired.

Animals↗