PubMed Health⌕ Search

Biomedical subjects

J M Sechler

Publications and source records attributed to J M Sechler.

16 recordsLinked to original sources
PubMed1999

Antigen presentation determines the fate of the T memory response in vivo after sublethal gamma-irradiation.

The survival of memory T cells is critical to vaccination strategies for infectious diseases and cancer, whereas their elimination may be crucial for treatment of autoimmune states. We examined the consequences of gamma-irradiation, which induces apoptosis of memory T cells in vitro, on the memory response to MHC class I alloantigen in vivo. Sublethal gamma-irradiation of primed mice eliminated accelerated rejection of skin allografts but failed to induce tolerance. Accelerated rejection was restored in irradiated mice by infusion of bone marrow cells expressing the priming alloantigen on immunostimulatory APCs (dendritic cells), whereas the memory response was not restored by infusion of bone marrow cells expressing the priming alloantigen on nonstimulatory APCs (B cells). Strikingly, irradiated mice infused with nonstimulatory bone marrow APCs exhibited long-term survival or tolerance to skin grafts expressing the priming MHC class I alloantigen. The mechanism of tolerance in this setting is explored.

Animals↗
PubMed1999

Safe and effective regulation of hematocrit by gene gun administration of an erythropoietin-encoding DNA plasmid.

This work examines the effect of delivering a DNA plasmid encoding murine erythropoietin (pVRmEpo) to BALB/c mice by gene gun. Whereas intramuscular injection elicits a rise in hematocrit persisting >8 months, intradermal delivery triggers the dose-dependent secretion of biologically active erythropoietin (Epo) for approximately 1 month. Repeated administration of pVRmEpo by gene gun elicits a stable increase in hematocrit. The source of the Epo produced following gene gun delivery was analyzed by periodically grafting the site of injection onto naive recipients. Results indicate that both stationary cells (presumably keratinocytes) and migratory (presumably dendritic) cells were transfected and secreted biologically active Epo in vivo. Gene gun administration of plasmid DNA appears to be safe, and provides an additional strategy for achieving the regulated secretion of an exogenous gene product.

Anemia↗
PubMed1998

Induction of antigen-specific hyporesponsiveness by transplantation of hemopoietic cells containing an MHC class I transgene regulated by a lymphocyte-specific promoter.

We explored a novel approach to tolerance induction by the transplantation of bone marrow (BM) cells (BMCs) that themselves do not express a foreign histocompatibility Ag, but which give rise to mature lymphocytes that do so. Lines of transgenic (FVB) mice were generated that contained an MHC class I Dd cDNA regulated by a CD2 promoter. Because the CD2 promoter is lymphocyte-specific and activated relatively late in lymphocyte ontogeny, Dd is expressed on most mature lymphocytes in the periphery but only on developing B cells in the BM of transgenic mice. Transgenic BMCs are tolerogenic and reproducibly engraft in nontransgenic mice using a conditioning regimen that is nonpermissive for the engraftment of conventional (MHC promoter) Dd-transgenic BMCs. Engrafted BMCs generate transgene-expressing lymphocytes and confer a state of Ag-specific hyporesponsiveness on the host that is primarily attributable to a peripheral mechanism. The strategies by which tolerance can be optimized in this system are discussed.

Animals↗
PubMed1998

Contribution of cells at the site of DNA vaccination to the generation of antigen-specific immunity and memory.

Gene gun-mediated DNA vaccination stimulates an immune response characterized by the activation of IgG-secreting B cells and IFN-gamma-secreting T cells. To monitor the contribution of cells at the site of vaccination to this process, transfected skin was periodically removed and grafted onto naive recipients. Immediate removal of vaccinated skin abrogated the development of an immune response. Low-level IgG production was stimulated when the vaccination site was left in place for > or = 5 h, with the strength of this response increasing the longer the site remained intact (for up to 2 wk). Measurable primary T cell responses were observed in animals whose vaccination site remained in place for > or = 1 day. Skin grafts transferred 0 to 24 h postvaccination stimulated a primary immune response in naive recipients. Memory B and T cells were generated in animals whose site of vaccination remained intact for 5 to 12 h. Skin transferred within 12 h of vaccination triggered memory B and T cell development in graft recipients, while the removal of skin >12 h postvaccination did not reduce memory in vaccinated mice. These findings suggest that 1) primary immunity is induced by cells that migrate rapidly from the site of immunization, 2) nonmigratory cells influence the magnitude of this primary response, and 3) migratory cells alone are responsible for the induction of immunologic memory.

Animals↗
PubMed1997

Genetic variation among 129 substrains: practical consequences.

We designed a series of experiments to define the role of IFN-gamma in cellular interactions mediating graft rejection by assessing the rejection of H-Y disparate grafts in both ligand and receptor knockout mice and their control inbred strain. In the course of these studies it became apparent that neither knockout strain is histocompatible with the putative control and that the putative control is not histocompatible with either knockout strain. In the process of deducing why this might be so, it became apparent that the putative control is not an inbred strain of mouse. Thus, in the absence of rigorous genetic control, the utility of such knockout strains of mice for assessing the effects of cytokines and receptors in transplantation and autoimmunity is limited.

Animals↗
PubMed1996

Induction of murine acquired immunodeficiency syndrome (MAIDS) in allophenic mice generated from strains susceptible and resistant to disease.

To examine whether a retroviral disease can be controlled in animals in which cells from a resistant strain coexist in a state of immunological tolerance with cells from a susceptible strain, allophenic mice were constructed and infected with LP-BM5 murine leukemia viruses which induce a fatal disorder, termed murine acquired immunodeficiency syndrome (MAIDS), characterized by lymphoproliferation and immunodeficiency in susceptible inbred strains of mice. We found that in two different strain combinations, resistance to MAIDS was contingent on the presence in individual animals of >50% of lymphocytes of resistant strain origin and correlated with reduction or elimination of retrovirus. In contrast, animals harboring substantial, but less than predominant, numbers of genetically resistant lymphocytes developed disease and died within the same time frame as susceptible control mice with uncontained proliferation of retrovirus.

Animals↗
PubMed1994

Identification and culture of Kaposi's sarcoma-like spindle cells from the peripheral blood of human immunodeficiency virus-1-infected individuals and normal controls.

We examined 26 patients with human immunodeficiency virus-1 (HIV-1)-associated Kaposi's sarcoma (KS), and 76 HIV-1-infected (HIV-1+) people without KS or uninfected (HIV-1-) controls for the presence of circulating KS-like spindle cells. Adherent cells that had spindle morphology and several characteristics of spindle cells of KS lesions (KS cells) were identified in the peripheral blood mononuclear cell fraction only after culture in the presence of conditioned medium (CM) from activated lymphocytes. The peripheral blood-derived spindle cells (PBsc) expressed a variety of endothelial cell markers, such as Ulex europaeus I lectin, EN4, EN2/3, EN7/44, CD13, CD34, CD36, CD54, ELAM-1, and HLA-DR. However, they were negative for CD2, CD19, PaIE, and factor VIII-related antigen. The PBsc produced angiogenic factors as evidenced by the ability of CM from these cells to promote growth of normal vascular endothelial cells. In addition, subcutaneously injected PBsc stimulated angiogenesis in vivo in athymic nude mice. We determined that the number of PBsc grown from the peripheral blood of HIV-1+ patients with KS or at high risk to develop KS were increased by 78-fold (P = .0001) and 18-fold (P = .005), respectively, when compared with HIV-1- controls. The number of spindle cells cultured from the HIV-1+ patients at low risk for developing KS, eg, HIV-1+ injection drug users, showed no statistical increase when compared with HIV-1- controls. The presence of increased PBsc with characteristics of KS cells in HIV-1+ KS patients or patients at high risk for developing KS gives insights into the origin of KS cells and may explain the multifocal nature of the disease. In addition, this may be useful in predicting the risk of KS development.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Regression of experimental Burkitt's lymphoma induced by Epstein-Barr virus-immortalized human B cells.

Epstein-Barr virus (EBV)-immortalized human B cells survive only transiently when injected subcutaneously into athymic mice, whereas Burkitt's lymphoma cells give rise to progressively growing subcutaneous tumors. In this study, we tested whether these Burkitt's tumors could be induced to regress via a bystander effect induced by EBV-immortalized B cells. Simultaneous inoculation of EBV-immortalized B cells and Burkitt's lymphoma cells in the same subcutaneous site resulted in tumors that regressed with necrosis and scarring. Similarly, simultaneous inoculation of EBV-immortalized B cells and Burkitt's lymphoma cells in separate subcutaneous sites resulted in regression of a proportion of the Burkitt's tumors. Furthermore, most of the established human Burkitt's tumors regressed with necrosis and scarring after intratumor inoculations with EBV-immortalized B cells. The EBV-immortalized B cells continued to exert this antitumor effect even when killed with irradiation. The experimental approach to Burkitt's lymphoma treatment described here exploits the ability of athymic mice to reject EBV-immortalized B cells to target an effective antitumor response to malignant cells normally incapable of eliciting it.

Animals↗
PubMed1994

Assessment of alloreactive T cell subpopulations of aged mice in vivo. CD4+ but not CD8+ T cell-mediated rejection response declines with advanced age.

The present investigation explored age-related alterations in T cell populations mediating allospecific responses in vivo. Healthy aged and young H-2b and H-2bxH-2k mice were engrafted with major histocompatibility complex (MHC) class II-disparate bm12 skin, rejection of which requires CD8+ T cells, and MHC class I-disparate bm1 skin, rejection of which requires CD8+ T cells. Aged mice of both genders exhibited prolonged survival of bm12 skin grafts relative to their young counterparts but rejected bm1 skin grafts at a rate equivalent to that of young mice. Consistent with prolonged survival of bm12 skin grafts, markedly diminished levels of Iabm12 CTL activity were elicited from T cells of aged mice in vitro. However, no such decline was observed in the level of Kbm1 CTL from T cells of aged mice. The alterations in Iabm12 allospecific responses were not attributable to quantitative changes in CD4+ T cells of aged mice, and addition of soluble T cell helper factors to response cultures of aged mice did not augment Iabm12 cytotoxic T lymphocytes activity. These data demonstrate that aging fundamentally affects CD4+ T cell-mediated allospecific responses particularly in vivo, and that deficient generation of soluble T cell helper factors alone cannot explain this deficit.

Aging↗
PubMed1992

Acute inflammatory response to cowpox virus infection of the chorioallantoic membrane of the chick embryo.

The chick embryo chorioallantoic membrane was used to study the acute inflammatory response in the absence of contributions from the immune system. In preliminary experiments, lesions of wild-type cowpox virus strain Brighton (CPV-BR) and a 38K gene deletion mutant of CPV-BR (CPV-BR.D1) were compared with vaccinia virus (strains WR and Copenhagen), fowlpox virus, laryngotracheitis virus, and infectious tenosynovitis virus, and were ranked for degree of induced inflammation. The maximal and minimal inflammatory responses were observed with CPV-BR.D1 and CPV-BR viruses, respectively. CPV-BR.D1 lacks a 38K gene which encodes an anti-inflammatory 38-kDa protein that has homology to SERPINs. The kinetics and character of the inflammatory response were examined further in the wild-type CPV-BR and mutant CPV-BR.D1 infections using cell counts, electron microscopy, and assays for inflammatory cell activation. CPV-BR virus infection rapidly spread through the ectoderm, uniformly infecting all cells with the production of large amounts of virions and viral-induced cytopathic effect, but evoking little or no inflammatory response until 144 hr p.i. The CPV-BR.D1 infection, on the other hand, was rapidly contained by a dexamethasone-sensitive inflammatory response mainly of activated heterophils which was advanced by 36 hr p.i. Both infections resulted in disseminated disease with similar numbers of liver lesions and only a slight difference in the LD50, with the CPV-BR.D1 values being higher than that for CPV-BR virus. In this model, the acute inflammatory response alone is unable to prevent disseminated disease and associated mortality.

Acute Disease↗
PubMed1991

Immunoglobulin G antineutrophil cytoplasmic antibodies are produced in the respiratory tract of patients with Wegener's granulomatosis.

Wegener's granulomatosis (WG) is a small-vessel vasculitis of unknown etiology that usually involves the upper and lower respiratory tract and the kidneys. Recently, an association has been made between the presence of serum antineutrophil cytoplasmic antibodies (ANCA) and WG. Because WG frequently involves the lung, we sought to evaluate bronchoalveolar lavage (BAL) fluids obtained from 14 patients with WG for the presence of ANCA. Immunoglobulin (Ig) G ANCA was found in the BAL with the same staining patterns as observed in the serum. Patients with active disease had the highest serum and BAL IgG ANCA titers. IgA or IgM ANCA was not detected in the serum or BAL of these patients. Protein analysis of BAL fluid revealed that patients with active, untreated WG had approximately a fourfold elevation in total protein (41.3 versus 10.5 mg/dl), with a disproportionately greater increase in the ratio of IgG to albumin (BAL IgG index = 1.49, normal = 0.74; p = 0.027). The increase of the IgG index in patients with active WG suggests that local production of IgG ANCA occurs in the lungs.

Adult↗
PubMed1991

Bronchoalveolar lavage analysis in Wegener's granulomatosis. A method to study disease pathogenesis.

A prospective analysis of bronchoalveolar lavage (BAL) in 13 patients with Wegener's granulomatosis (WG), 20 disease control subjects with idiopathic pulmonary fibrosis (IPF), and 24 normal control subjects was conducted to (1) evaluate the quality of the alveolar inflammatory response associated with active WG; (2) determine whether antineutrophil cytoplasmic antibody (ANCA) is present in alveolar fluid and produced in the lungs of patients with WG; and (3) determine whether inhaled particles or infectious agents may play an etiologic role in WG. BAL in untreated active WG had a marked increase in neutrophils (mean = 42% of total WBC count), and usually in eosinophils (mean = 4%) compared with that in normal control subjects (1.6% neutrophils, 0% eosinophils), and untreated WG in remission (5.9% neutrophils, 0% eosinophils). Disease control subjects with IPF, a process known to be associated with neutrophilic alveolitis, had an increased population of neutrophils (15.4%) and eosinophils (2.7%) in BAL. Leukocyte remnants, as well as intact leukocytes, could be identified within BAL macrophages in the patients with WG and IPF, and rarely in the normal control subjects. Normal subjects and control patients with IPF were all negative for ANCA in serum, whereas ANCA was found in serum and BAL in all patients with active WG who had generalized disease. Protein analysis of BAL revealed a disproportionate increase in the IgG to albumin ration compared with serum values (IgG index) in patients with active untreated disease. The increase in the IgG index suggests that IgG with ANCA reactivity is produced by pulmonary lymphoid tissue. An infectious agent in BAL was not identified by any of the techniques applied in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Cloning of a 67-kD neutrophil oxidase factor with similarity to a noncatalytic region of p60c-src.

Chronic granulomatous diseases (CGDs) are characterized by recurrent infections resulting from impaired superoxide production by a phagocytic cell, nicotinamide adenine dinucleotide phosphate (reduced) (NADPH) oxidase. Complementary DNAs were cloned that encode the 67-kilodalton (kD) cytosolic oxidase factor (p67), which is deficient in 5% of CGD patients. Recombinant p67 (r-p67) partially restored NADPH oxidase activity to p67-deficient neutrophil cytosol from these patients. The p67 cDNA encodes a 526-amino acid protein with acidic middle and carboxyl-terminal domains that are similar to a sequence motif found in the noncatalytic domain of src-related tyrosine kinases. This motif was recently noted in phospholipase C-gamma, nonerythroid alpha-spectrin (fodrin), p21ras-guanosine triphophatase-activating protein (GAP), myosin-1 isoforms, yeast proteins cdc-25 and fus-1, and the 47-kD phagocyte oxidase factor (p47), which suggests the possibility of common regulatory features.

Amino Acid Sequence↗
PubMed1989

Human non-transformed monocyte-derived macrophage cell lines.

We have demonstrated that human blood monocyte-derived macrophages can be passaged from primary cultures and replicate. Passaged cells have typical macrophage characteristics: they are non-specific esterase positive, phagocytic, and respond to 3 days of treatment with interferon-gamma with enhanced production of superoxide on stimulation with PMA. The passaged cells express Fc, CR1, CR3 and FMLP receptors. Both primary and passaged cultures constitutively produce CSF-1 after 3 weeks in culture. Cultures studied between 7 and 16 weeks in culture produce 3712 +/- 478 U of CSF-1 per 10(6) cells. Randomly selected lines were examined to look for cell proliferation by looking at numbers of cells over time and by labelling cells with tritiated thymidine to determine the number of cells synthesizing DNA. In addition, the cells can be frozen at the time of isolation and stored for at least 1 year, and then thawed and shown to retain functional activity. Human monocyte-derived macrophages can be cultured as finite cell lines.

Carboxylesterase↗
PubMed1988

Recombinant human interferon-gamma reconstitutes defective phagocyte function in patients with chronic granulomatous disease of childhood.

Monocytes from 19 of 30 patients with the classic phenotype of chronic granulomatous disease of childhood (CGD) responded to 3 days of treatment in culture with recombinant human interferon-gamma (rHuIFN-gamma) at 100 units/ml by producing superoxide after stimulation with phorbol 12-myristate 13-acetate. Cells from 15 of 16 patients with cytochrome b-positive CGD (15 with autosomal and 1 with X chromosome-linked inheritance) and cells from 4 of 14 patients with cytochrome b-negative CGD (13 with X chromosome-linked and 1 with autosomal recessive inheritance) responded. Subcutaneous rHuIFN-gamma (0.01-0.05 mg/m2) administered as a single dose, daily or every other day, for five or six doses to 3 patients whose phagocytes responded to rHuIFN-gamma in vitro resulted in significant improvement in phagocyte bactericidal activity against Staphylococcus aureus and increases in superoxide production. Studies on 1 patient's cells indicated the increases in superoxide production correlated with increased membrane cytochrome b. The effects of rHuIFN-gamma persisted for more than a week following cessation of therapy. Thus, we have demonstrated a partial correction in vivo of these CGD patients' phagocyte defect with rHuIFN-gamma. Moreover, the data suggest that a significant proportion of patients with CGD will respond to rHuIFN-gamma with augmentation of phagocyte microbicidal function.

Blood Bactericidal Activity↗