Biomedical subjects

L D Shultz

Publications and source records attributed to L D Shultz.

At least 55 records · Page 3Linked to original sources

PubMed1998

Follicular dendritic cell (FDC) precursors in primary lymphoid tissues.

The origin of follicular dendritic cells (FDC) is unresolved, and as such, remains controversial. Based on the migration of Ag-transporting cells (ATC) into lymphoid follicles and the phenotypic similarity between FDC and ATC, one hypothesis is that ATC may represent emigrating FDC precursors. This contrasts with the view that FDC originate from local stromal cells in the secondary lymphoid tissues. Mice homozygous for the severe combined immunodeficiency (prkdc(scid)) mutation (scid) lack FDC. Thus, they provide a powerful tool for assessing de novo generation of FDC. To test whether FDC precursors could be found in bone marrow or fetal liver, scid/scid mice were reconstituted with either: 1) bone marrow cells from (BALB/c x C57BL/6)F1 donors, 2) bone marrow cells from ROSA BL/6 F1 (lacZ-transfected) mice, 3) rat bone marrow cells, or 4) rat fetal liver cells. Six to eight weeks after reconstitution with F1 bone marrow, cells reactive with the FDC-labeling mAb, FDC-M1, also expressed donor class I molecules on their surfaces. Similarly in mice reconstituted with lacZ-transfected bone marrow cells, these cells were also positive for the lacZ gene product. Furthermore, in spleens of animals reconstituted with either rat bone marrow or rat fetal liver, rat FDC were identified using the specifically labeling mAb, ED5. In all cases, host FDC were also present, indicating that scid/scid mice have FDC precursors that will mature in the presence of allogeneic or xenogeneic lymphoid cells. In summary, FDC can be derived from progenitor cells present in primary lymphoid tissues.

Animals↗

PubMed1998

The pathophysiological significance of nondesmoglein targets of pemphigus autoimmunity. Development of antibodies against keratinocyte cholinergic receptors in patients with pemphigus vulgaris and pemphigus foliaceus.

OBJECTIVES: To determine whether nondesmoglein (non-Dsg) autoantibodies are pathogenic and whether they recognize keratinocyte cholinergic receptors that control cell adhesion because antikeratinocyte autoimmunity in patients with pemphigus vulgaris is not limited to the development of autoantibodies to Dsg. DESIGN: To determine whether non-DSg autoantibodies are pathogenic, we sought to induce pemphigus in genetically engineered neonatal mice lacking Dsg 3 using pemphigus vulgaris IgGs that did not cross-react with Dsg 1. To determine whether pemphigus autoimmunity involves keratinocyte cholinergic receptors, the latter were separated from cell membranes of human keratinocytes, tagged with the covalent label [3H]propylbenzilylcholine mustard, and used as an antigen in a radioimmunoprecipitation assay of 34 pemphigus vulgaris and 6 pemphigus foliaceus serum samples. SETTING: The dermatologic clinics of the University of Minnesota, Minneapolis; the Mayo Clinic, Rochester, Minn; and the University of California-Davis Medical Center, Sacramento. PATIENTS: Serum samples were collected from 34 patients with pemphigus vulgaris and 6 patients with pemphigus foliaceus (aged 31-89 years) and from 7 age-similar patients of both sexes with nonpemphigus blistering or the following immune-mediated conditions: pemphigoid gestation, bullous drug eruption, lupus erythematosus, erythema nodosum, urticaria, acute contact dermatitis, and skin ulcers. MAIN OUTCOME MEASURES: Clinical, laboratory, and histopathologic findings. RESULTS: Extensive skin blistering accompanied by the Nikolsky sign and suprabasilar acantholysis was induced in the Dsg3null mice that received pemphigus, but not normal human IgGs. In the radioimmunoprecipitation assays for reactivity with cholinergic receptors, the mean radioactivity precipitated by pemphigus serum samples significantly exceeded both normal- and disease-control levels (P = .001-.02). The mean individual levels of radioactivity precipitated by 34 pemphigus vulgaris and pemphigus foliaceus serum samples (85%) exceeded control values by a mean of approximately 2.6 times. CONCLUSIONS: Autoantibodies to keratinocyte cell-surface molecules other than Dsg 1 and Dsg 3 can induce clinical features of pemphigus vulgaris. Patients with pemphigus vulgaris and those with pemphigus foliaceus develop IgG antibodies that precipitate radiolabeled cholinergic receptors. Because these receptors control keratinocyte adhesion and motility, their inactivation by autoantibodies may elicit intracellular signals that cause disassembly of desmosomes, leading to acantholysis and blistering.

Acantholysis↗

PubMed1998

Lymphadenopathy, elevated serum IgE levels, autoimmunity, and mast cell accumulation in flaky skin mutant mice.

The autosomal recessive mutation "flaky skin" (fsn) causes pleiotropic abnormalities in the immune and hematopoietic systems accompanied by pathologic changes in the skin. Homozygotes (fsn/fsn) showed increased size and histological alterations in the spleen and lymph nodes. Abnormalities in lymphoid architecture of the spleen in fsn/fsn mice were accompanied by marked increases in total numbers of B cells, macrophages, and immature erythroid cells. Splenic B cells displayed elevated MHC class II expression. Serum IgE levels were greater than 100 microg/ml by 10 weeks of age, representing > 7000-fold increase compared with normal littermates. This increased IgE level was associated with elevated IL-4 production by spleen cells and with increased amounts of serum IL-4. Serum IgM, IgG1, and IgG2b levels were also increased in fsn/fsn mice while IgG3 was decreased. Autoimmunity in fsn/fsn mice was evidenced by glomerulonephritis accompanied by immune complex deposition in the kidneys, increased serum blood urea nitrogen levels, and the presence of circulating anti-double-stranded DNA autoantibodies. Pathological changes in the skin of fsn/fsn mice were characterized by epidermal hyperplasia and mixed dermal inflammation. Increased numbers of mast cells were also observed in the dermis of the truncal skin as well as in the epithelial stomach. These marked immunological abnormalities suggest that the fsn locus encodes a major immunoregulatory molecule important in multiple immune and hematopoietic functions.

Abnormalities, Multiple↗

PubMed1998

CSF-1 regulation of Il6 gene expression by murine macrophages: a pivotal role for GM-CSF.

We test the hypothesis that the monocyte-macrophage colony-stimulating factor (CSF-1 or M-CSF) plays a major role in the inflammatory responses of Mphi by acting as a priming agent that heightens their responsiveness to secondary stimulation by other mediators. We previously reported that CSF-1 induced peritoneal Mphi (PMphi) to transcribe several genes including interleukin-6 (Il6) and granulocyte-macrophage colony-stimulating factor (Csfgm). It was reported that the Il6 and Csfgm genes were individually regulated by different pathways but it was not clear to what extent the two genes interacted during Mphi-mediated inflammatory responses. We now show that CSF-1 induces the release of bioactive GM-CSF from mouse resident PMphi. GM-CSF induces Il6 gene expression and synergizes with CSF-1 to induce the release of large amounts of IL-6. PMphi from C57BL/6J-Csfgm(null) mice were shown to release minimal IL-6 in response to CSF-1 and to express a much reduced response to the highly stimulatory combination of CSF-1 and lipopolysaccharide (LPS). Exogenous recombinant GM-CSF restored the IL-6 response of GM-CSF null PMphi to a great extent but not completely. As controls, three other recombinant proteins were tested but of these only tumor necrosis factor alpha (TNF-alpha) was shown to synergize with both CSF-1 and GM-CSF. Using PMphi from mice deficient in the expression of the Il6 gene, it was shown that they released two- to threefold more GM-CSF in response to CSF-1 than their control counterparts. However, an exogenous supply of recombinant IL-6 had no effect on GM-CSF release. The data indicate that the pathways regulating Il6 gene expression are under the control of a complex network of cytokine interactions involving at least CSF-1, GM-CSF, and TNF-alpha, with the added possibility that IL-6 may exert modulatory activity within this network.

Animals↗

PubMed1998

SCID mouse models of human stem cell engraftment.

The discovery of the severe combined immunodeficiency (scid) mouse mutation has provided a tool for establishment of small animal models as hosts for the in vivo analysis of normal and malignant human pluripotent hemopoietic stem cells. Intravenous injection of irradiated scid mice with human bone marrow, cord blood, or G-CSF cytokine-mobilized peripheral blood mononuclear cells, all rich in human hemopoietic stem cell activity, results in the engraftment of a human hemopoietic system in the murine recipient. This model has been used to identify a pluripotent stem cell, termed "scid-repopulating cell" (SRC) that is more primitive than any of the hemopoietic stem cell populations identified using the currently available in vitro methodology. In this review, we describe the development and use of this model system, termed Hu-SRC-SCID, and summarize the discoveries that have resulted from the investigation of human stem cells in this model. Finally, we detail the recent extension of the original Hu-SRC-SCID model system based on the C.B-17-scid mouse as the murine host to the Hu-SRC-NOD-SCID model based on the NOD-scid mouse as the host. The engraftment of human stem cells in the Hu-SRC-NOD-SCID model is enhanced over that observed in the Hu-SRC-SCID model and results in exceptionally high levels of human hemopoietic cells in the murine recipient. Future directions to further improve the Hu-SRC-NOD-SCID model system and the potential utility of this model in the preclinical and diagnostic arenas of hematology and oncology are discussed.

Animals↗

PubMed1998

Diethylcarbamazine (DEC) does not induce nitric oxide (NO) synthesis.

Diethylcarbamazine (DEC) was discovered in 1947 as a potent therapeutic agent in lymphatic filariasis and has been a mainstay of antifilarial therapy over the past five decades (R. I. Hewitt, et al., 1947, Journal of Laboratory and Clinical Medicine 32, 1304-1313). Several hundred million doses of this drug have been administered to people. Despite its widespread and successful use over this prolonged time scale, its mechanism of action remains obscure (R. M. Maizels and D. A. Denham, 1992, Parasitology 105 Suppl. 549-560). Numerous studies suggest that DEC has no direct effect on the parasite (F. Hawking and W. Laurie, 1949, Lancet 2, 146-147) and that it exerts its action by stimulating host immune defense mechanisms (F. Hawking et al., 1948, Lancet 2, 730-731), or by activating host platelets to become microfilaricidal (J. Y. Cesbron et al., 1987, Nature 325(6104) 533-536). Recent data from two different laboratories suggest that NO may be involved in host defense against filarial parasites (T. V. Rajan et al., 1996, Infection and Immunity 64(8), 3351-3353; M. J. Taylor et al., 1996, Parasitology 112, 315-322). We investigated whether DEC stimulates the production of NO from murine macrophages or rat endothelial cells. DEC did not stimulate the synthesis or secretion of NO from either, nor did it synergize with interferon-gamma or tumor necrosis factor-alpha in the induction of inducible NO synthase (iNOS). In addition, there was no consistent increase in the output of inorganic nitrate, the end product of NO metabolism, in the urines of rats treated with DEC. These data suggest that DEC does not achieve its therapeutic efficacy through the induction of host iNOS.

Animals↗

PubMed1998

Establishment and characterization of pro-B cell lines from motheaten mutant mouse defective in SHP-1 protein tyrosine phosphatase.

Mice homozygous for the motheaten (Hcph(me)) mutation lack a functional SHP-1 protein tyrosine phosphatase, show severe immunologic dysregulation and die at an early age. Severe pneumonitis in me/me mice is associated with abnormal proliferation of macrophages and granulocytes. Overgrowth of macrophages in long term cultures of me/me bone marrow has prevented analyses of lymphopoiesis in vitro. To establish hematopoietic cell lines from me/me mice, we cultured me/me bone marrow with the PA6 stromal cell line in the presence of antagonistic antibody against the receptor (c-Fms) for macrophage colony stimulating factor (M-CSF). In these cultures, overgrowth of M-CSF-dependent macrophages was suppressed by the antagonistic antibody and other hemopoietic cell lineages were generated efficiently from me/me bone marrow. By using this culture system, we established me/me pro-B cell clones (MEBs) with rearranged DH-JH but not VH-DJH. The growth of MEB clones required IL-7 and c-Kit ligand, corresponding to normal pro-B cells which express SHP-1. MEB cells were sensitive to starvation by either IL-7 or c-Kit ligand, resulting in apoptotic death. The present culture system, which supports hematopoiesis of me/me bone marrow, provides useful tools for the determination of the role of SHP-1 in signal transduction of B lymphopoiesis.

Animals↗

PubMed1998

Transgene expression of steel factor in the basal layer of epidermis promotes survival, proliferation, differentiation and migration of melanocyte precursors.

Mutations at the murine dominant white spotting (KitW) and steel (MgfSl) loci, encoding c-Kit receptor kinase and its ligand respectively, exert developmental defects on hematopoietic cells, melanocytes, germ cells and interstitial cells of Cajal. The expression patterns of steel factor (SLF) observed in the skin and gonads suggest that SLF mediates a migratory or a chemotactic signal for c-Kit-expressing stem cells (melanocyte precursors and primordial germ cells). By targeting expression of SLF to epidermal keratinocytes in mice, we observed extended distribution of melanocytes in a number of sites including oral epithelium and footpads where neither melanocytes nor their precursors are normally detected. In addition, enlarged pigmented spots of KitW and other spotting mutant mice were observed in the presence of the SLF transgene. These results provide direct evidence that SLF stimulates migration of melanocytes in vivo. We also present data suggesting that SLF does not simply support survival and proliferation of melanocytes but also promotes differentiation of these cells. Unexpectedly, melanocyte stem cells independent of the c-Kit signal were maintained in the skin of the SLF transgenic mice. After the elimination of c-Kit-dependent melanoblasts by function-blocking anti-c-Kit antibody, these stem cells continued to proliferate and differentiate into mature melanocytes. These melanoblasts are able to migrate to cover most of the epidermis after several months. The SLF transgenic mice described in this report will be useful in the study of melanocyte biology.

Animals↗

PubMed1998

Prolonged survival of rat islet and skin xenografts in mice treated with donor splenocytes and anti-CD154 monoclonal antibody.

Treatment of C57BL/6 mice with one transfusion of BALB/c spleen cells and a brief course of anti-CD154 (anti-CD40 ligand) antibody permits BALB/c islet grafts to survive indefinitely and BALB/c skin grafts to survive for approximately 50 days without further intervention. We now report adaptation of this protocol to the transplantation of islet and skin xenografts. We observed prolonged survival of rat islet xenografts in mice treated with donor-specific spleen cell transfusion and anti-CD154 monoclonal antibody (mAb). Challenge islet xenografts placed on these animals indicated that graft acceptance was species-specific but not strain specific. Spleen cells from recipients bearing intact grafts led to rejection of rat islet xenografts in scid mice, suggesting that graft acceptance was not due to complete clonal deletion of xenoreactive cells. We also observed prolonged survival of rat skin xenografts in mice treated with donor-specific transfusion and anti-CD154 mAb. Prolonged survival of skin xenografts was also species specific. We conclude that treatment with appropriately timed donor-specific transfusion and anti-CD154 mAb induces durable survival of both islet and skin xenografts in mice. Because this procedure is targeted directly at CD154, a co-activation molecule expressed predominantly by activated CD4+ T-cells, the results suggest that CD4+ cells have a major role in the cellular immune response to xenografts.

Adoptive Transfer↗

PubMed1998

Tumorigenicity of green turtle fibropapilloma-derived fibroblast lines in immunodeficient mice.

Fibroblast lines derived from normal skin and spontaneous or experimentally induced fibropapillomas of green turtles (Chelonia mydas) were established and propagated in medium composed of a combination of Dulbecco's minimal essential with F12 medium plus 10% fetal bovine serum at 30 degrees C. Fibropapilloma-derived fibroblasts were indistinguishable from normal skin fibroblasts in vitro. Tumor lines did not exhibit loss of contact inhibition, anchorage independence, or reduced serum requirements. Inoculation of primary and early-passage tumor cells into the medial margin of the pinna of C57BL/6J-nu/nu, C.B17-scid/scid, or NOD-scid/scid mice, however, resulted in fibroma formation, whereas inoculation of normal skin fibroblasts did not. Tumor-derived cells inoculated into the flanks of mice did not form tumors. The turtle origin of fibroblasts in tumors from mouse ears was confirmed by immunohistochemical and karyotype analysis. Fibroblast lines that were established from mouse ear fibromas had the normal karyotype (modal 2N = 55) of C. mydas. The cooler anatomic sites (ears) of immunodeficient mice are useful for confirming the tumorigenic (transformed) phenotype of green turtle fibropapillomatosis-derived fibroblasts. This mouse ear tumorigenicity test should facilitate studies of mechanisms of cellular transformation in green turtle fibropapillomatosis and other neoplastic diseases of poikilothermic vertebrates.

Animals↗

PubMed1998

Effects of granulocyte/macrophage colony-stimulating factor on the development and differentiation of CD5-positive macrophages and their potential derivation from a CD5-positive B-cell lineage in mice.

In co-cultures of either the murine pre-B cell line J13, fetal liver cells, or adult peritoneal or bone marrow cells with ST2 mouse bone marrow stromal cells in the presence of granulocyte/macrophage colony-stimulating factor (GM-CSF), the development of CD5+ macrophages was demonstrated by immunohistochemical staining and flow cytometry. Although CD5+ macrophages were not present in the peritoneal cavities of normal mice, approximately 30% of the peritoneal macrophages in viable motheaten (mev/mev) mice, deficient in SHP-1 protein tyrosine phosphatase, expressed cell surface CD5 and B220, markers for B cells. In the mev/mev mice, GM-CSF level in peritoneal fluid was increased significantly. At 5 days after daily intravenous injection with GM-CSF, many CD5+ macrophages appeared in the peritoneal cavity and in omental milky spots of normal mice but fewer in osteopetrosis (op) mutant mice, deficient in macrophage (M)-CSF. These results indicate that GM-CSF, in combination with M-CSF, induces the development and differentiation of CD5+ macrophages in the peritoneal cavity, particularly in the omental milky spots of mice. In the peritoneal cavity of GM-CSF-treated mice, the percentages of hematopoietic progenitor cells doubly positive for CD5 and CD34 or c-kit and of macrophage precursor cells doubly positive for CD5 and ER-MP58 or ER-MP20 were increased significantly during the development of CD5+ macrophages and CD5 B cells, suggesting that CD5+ macrophages and B cells may share a bipotential progenitor in vivo.

Animals↗

PubMed1998

Mature human hematopoietic cells in donor bone marrow complicate interpretation of stem/progenitor cell assays in xenogeneic hematopoietic chimeras.

Xenogeneic hematopoietic chimeras have been used to assay the growth and differentiation of human stem/progenitor cells. The presence of human hematopoietic cells in immunodeficient mice transplanted with human marrow cells may be caused by proliferation and differentiation of early stem/progenitor cells and/or proliferation of mature cells. Unpurified human marrow mononuclear cells, T cell-depleted, or stem/progenitor cell-enriched (CD34+ or CD34+CD38-) populations were injected into sublethally irradiated NOD/LtSz scid/scid (NOD/SCID) mice. High levels of human cells were detected in mice (hu/mu chimeras) transplanted with each of the above human marrow populations. Large numbers of mature human T lymphocytes were found in marrow, spleens, and thymuses from hu/mu chimeras that had been transplanted with unpurified human mononuclear marrow cells. Human immunoglobulin was detected in sera from these chimeras, and some exhibited a clinical syndrome suggestive of graft-versus-host disease. In contrast, in hu/mu chimeras that had received T cell-depleted or stem/progenitor cell-enriched populations, multilineage hematopoiesis (myeloid, B lymphoid, and progenitor cells by immunophenotype) was detected but T lymphocytes and human immunoglobulin were not; in addition, no human cells were detected in the thymuses. Thus, injection of adult human marrow cells into immunodeficient mice can result in hematopoietic chimerism for at least 3 months after transplant. However, the types of cells present in hu/mu chimeras differ depending on the human cell population transplanted. This should be taken into account when hematopoietic chimeras are used to assess human stem/progenitor cell function.

ADP-ribosyl Cyclase↗

PubMed1998

Aberrant regulation of bone trace elements in motheaten and osteopetrosis mutant mice.

Increasing numbers of genetic diseases involving bone development and models for these diseases have been identified recently. Analysis of these bone diseases have revealed that regulated action of multiple growth factors and subsequent signal transduction are essential for normal bone formation. In this paper, two murine mutant mice viable motheaten and osteopetrosis are analyzed. Mice with the recessive 'viable motheaten' mutation express a severe immunodeficiency syndrome and bone defects. Mutations at the motheaten locus were shown to be the result of aberrant splicing of the gene encoding hematopoietic cell phosphatase (Hcph). Mice homozygous for the osteopetrosis mutation develop congenital osteopetrosis due to a severe deficiency of osteoclasts. It has been recognized that bone trace element composition analysis helps to define bone-related physiological conditions. We have analyzed bone trace element composition in viable motheaten and osteopetrosis mutant animal models in this study. In order to gain insights into the effects of particular genetic defects on bone trace element composition, inductively coupled plasma atomic emissions spectrometry (ICP-AES) analysis was performed. Marked changes in bone trace element levels were found in limb bones of viable motheaten and osteopetrosis mutant mice. An assessment of these trace element spectrum in the two mutant models with respect to each genetic defects are discussed in this paper.

Animals↗

PubMed1998

Bone remodeling and macrophage differentiation in osteopetrosis (op) mutant mice defective in the production of macrophage colony-stimulating factor.

Mice homozygous for the osteopetrosis (op) mutation are characterized by defective differentiation of osteoclasts, monocytes, and tissue macrophages due to a lack of functional macrophage colony-stimulating factor (M-CSF/CSF-1) activity. In young (4-6 week-old) op/op mice, the bone marrow cavities were filled with spongious bone. In aged (50-72 week-old) op/op mice, the bone marrow cavities were markedly reconstructed and marrow hematopoiesis was expanded. Numbers of osteoclasts and bone marrow macrophages in aged op/op mice were increased but most of the osteoclasts were mononuclear cells and showed poorly developed ruffled borders. Lysosomes of bone marrow macrophages were laden with abundant crystalloid materials in aged op/op mice and aged littermate mice. However, such macrophages were not observed in young op/op mice nor in young littermates. In contrast to the marked increase in numbers of osteoclasts and macrophages in the bone marrow, the number of Kupffer cells in the liver did not increase in aged op/op mice. Kupffer cells in aged op/op mice did not show ultrastructural maturation with aging and contained a few crystalloid structures. M-CSF administration to aged op/op mice induced numerical increases in Kupffer cells and lysosomes in Kupffer cells, disappearance of crystalloid structures in lysosomes of Kupffer cells, and the development of ruffled border in osteoclasts. These findings indicate that M-CSF-independent mechanisms for macrophage and osteoclast development in aged op/op mice are restricted to bone marrow. M-CSF plays important roles in the differentiation of macrophage and osteoclast and the production and function of lysosomes.

Aging↗

PubMed1998

SHP-1 deficiency in B-lineage cells is associated with heightened lyn protein expression and increased lyn kinase activity.

SHP-1 protein tyrosine phosphatase is a critical regulator of signal transduction in hematopoietic cells. In the present study, we derived two pre-B cell lines, PBCL-1 and PBCL-2, from normal and SHP-1-deficient motheaten mice, respectively, and characterized hyperphosphorylated proteins in PBCL-2 cells to identify SHP-1-regulated molecules. Two proteins of 56 and 53 kDa (p56/p53) in PBCL-2 cells showed heightened phosphorylation (3- to 6-fold) in comparison with those in PBCL-1. p56/p53 were identified as the two forms of the lyn protein tyrosine kinase (p56/p53lyn), which showed increased kinase activity in PBCL-2 cells. Interestingly, the protein levels of p56/53lyn were found to be 3- to 6-fold higher in PBCL-2 cells than those in PBCL-1, whereas the transcript levels of lyn in the two cell lines were comparable. A modest increase in p56/53lyn protein expression was also detected in primary spleen B cells of motheaten mice. Thus SHP-1 deficiency in B-lineage cells, especially pre-B cells, is associated with increased lyn protein expression and kinase activity. These data indicate a role for SHP-1 in regulating lyn through a post-transcriptional mechanism.

Animals↗

PubMed1997

An interleukin 4 (IL-4)-independent pathway for CD4+ T cell IL-4 production is revealed in IL-4 receptor-deficient mice.

IL-4 receptor alpha chain (IL-4Ralpha)-deficient mice were generated by gene-targeting in BALB/c embryonic stem cells. Mutant mice showed a loss of IL-4 signal transduction and functional activity. The lack of IL-4Ralpha resulted in markedly diminished, but not absent, TH2 responses after infection with the helminthic parasite Nippostrongylus brasiliensis. CD4+, CD62L-high, and CD62L-low T cell populations from uninfected IL-4Ralpha-/- mice were isolated by cell sorting. Upon primary stimulation by T cell receptor cross-linkage, the CD62L-low, but not the CD62L-high, cells secreted considerable amounts of IL-4, which was strikingly enhanced upon 4-day culture with anti-CD3 in the presence or absence of IL-4. CD62L-low cells isolated from IL-4Ralpha-/-, beta2-microglobulin-/- double homozygous mice produced less IL-4 than did either IL-4Ralpha-/- or wild-type mice. These results indicate that an IL-4-independent, beta2-microglobulin-dependent pathway exists through which the CD62L-low CD4+ population has acquired IL-4-producing capacity in vivo, strongly suggesting that these cells are NK T cells.

Animals↗

PubMed1997

DNA-binding antibodies from viable motheaten mutant mice: implications for B cell tolerance.

C57BL/6 me(v)/me(v) (viable motheaten) mice have defective hemopoietic cell protein-tyrosine phosphatase (HCP, SHP-1) and are a model in which to study the role of this phosphatase in immune regulation and hemopoietic development. Immune defects in these mice include hypergammaglobulinemia, production of multiple autoantibodies, and glomerular nephritis. The presence of self-reactive Abs in these mice is an enigma, since it has been demonstrated that they have increased negative selection against self-reactive transgenic Abs. It was of interest to examine autoantibodies from these mice to identify reactivity or structural features that might account for their persistence and expansion in the repertoire. Abs to DNA were selected for investigation, since they have been characterized extensively from normal and autoimmune strains of mice. Viable motheaten mice had high titers of IgM, anti-dsDNA Abs, and all 12 anti-DNA hybridomas generated were also IgM. They had high avidity for dsDNA, also bound to ssDNA, but were not polyreactive. They used V(H) and V(L) gene families found in anti-DNA Abs from other strains, which reinforces evidence that there is preferential use of a restricted number of germline elements in anti-DNA Abs. The results indicate that Hcph-mutant mice do not delete DNA-reactive B cells, nor are they able to maintain these B cells in a state of anergy. Evidence for positive selection and clonal expansion after V-D-J rearrangement was also seen, in that several Abs expressed the same heavy chain in combination with different light chains, which is also a hallmark of the autoimmune anti-DNA response.

Amino Acid Sequence↗

PubMed1997

LacZ and interleukin-3 expression in vivo after retroviral transduction of marrow-derived human osteogenic mesenchymal progenitors.

Human marrow-derived mesenchymal progenitor cells (hMPCs), which have the capacity for osteogenic and marrow stromal differentiation, were transduced with the myeloproliferative sarcoma virus (MPSV)-based retrovirus, vM5LacZ, that contains the LacZ and neo genes. Stable transduction and gene expression occurred in 18% of cells. After culture expansion and selection in G418, approximately 70% of neo(r) hMPCs co-expressed LacZ. G418-selected hMPC retain their osteogenic potential and form bone in vivo when seeded into porous calcium phosphate ceramic cubes implanted subcutaneously into SCID mice. LacZ expression was evident within osteoblasts and osteocytes in bone developing within the ceramics 6 and 9 weeks after implantation. Likewise, hMPCs transduced with human interleukin-3 (hIL-3) cDNA, adhered to ceramic cubes and implanted into SCID mice, formed bone and secreted detectable levels of hIL-3 into the systemic circulation for at least 12 weeks. These data indicate that genetically transduced, culture-expanded bone marrow-derived hMPCs retain a precursor phenotype and maintain similar levels of transgene expression during osteogenic lineage commitment and differentiation in vivo. Because MPCs have been shown to differentiate into bone, cartilage, and tendon, these cells may be a useful target for gene therapy.

Adult↗