Inheritance and dominance of self-incompatibility alleles in polyploid Arabidopsis lyrata.

Natural populations of diploid Arabidopsis lyrata exhibit the sporophytic type of self-incompatibility system characteristic of Brassicaceae, in which complicated dominance interactions among alleles in the diploid parent determine self-recognition phenotypes of both pollen and stigma. The purpose of this study was to investigate how polyploidy affects this already complex system. One tetraploid population (Arabidopsis lyrata ssp kawasakiana from Japan) showed complete self-compatibility and produced viable selfed progeny for at least three generations subsequent to field collection. In contrast, individuals from a second tetraploid population (A. lyrata ssp petraea from Austria) were strongly self-incompatible (SI). Segregation of SI genotypes in this population followed Mendelian patterns based on a tetrasomic model of inheritance, with two to four alleles per individual, independent segregation of alleles, and little evidence of dosage effects of alleles found in multiple copies. Similar to results from diploids, anomalous compatibility patterns involving particular combinations of individuals occurred at a low frequency in the tetraploids, suggesting altered dominance in certain genetic backgrounds that could be due to the influence of a modifier locus. Overall, dominance relationships among S-alleles in self-incompatible tetraploid families were remarkably similar to those in related diploids, suggesting that this very important and complicated locus has not undergone extensive modification subsequent to polyploidization.

B cell-deficient mice have increased susceptibility to HSV-1 encephalomyelitis and mortality.

We studied the susceptibility of B cell-deficient mice to encephalomyelitis following intraperitoneal inoculation of HSV-1. B cell-deficient mice developed striking CNS signs including tail atony, clumsy gait and limb paralysis after HSV-1 infection. In addition, B cell-deficient mice had decreased survival (LD50 = 2.2 x 10(7) PFU) compared to control C57BL/6 mice (LD50 = 2.3 x 10(8) PFU). B cell-deficient mice had encephalomyelitis and detectable virus in the brain 7 days post-infection while C57BL/6 mice did not. Passive transfer of hyperimmune sera protected B cell-deficient mice from death, suggesting a role for antibody in susceptibility to HSV-1 encephalomyelitis.

In the absence of T cells, natural killer cells protect from mortality due to HSV-1 encephalitis.

The importance of natural killer (NK) cells in the resistance to herpes simplex virus type 1 (HSV-1), a common infection of immunocompromised patients, is unclear. Previous data on the role of NK cells in murine HSV-1 infection has been contradictory. Adoptive transfer studies suggested that NK cells mediated resistance to HSV-1, but in vivo depletion approaches demonstrated that NK cells were not important. We studied the course of HSV-1 infection after intranasal (i.n.) inoculation of E26 mice (lacking NK and T cells), T cell knockout (T cell ko) mice (lacking T cells only), or normal control mice. The E26 mice showed greater mortality and an impaired ability to clear virus from lung and brain compared to T cell ko mice and control mice, and had severe necrotizing HSV-1 encephalitis. Therefore, the data support the hypothesis that NK cells play an important role in the natural defense of murine HSV-1 infection.

Recombinant CD40L treatment protects allogeneic murine bone marrow transplant recipients from death caused by herpes simplex virus-1 infection.

Posttransplant infection associated with host immune deficiency is the major cause of nonrelapse mortality of human bone marrow transplant recipients. In a new murine model of posttransplant infection, allogeneic bone marrow transplant recipients were infected with herpes simplex virus-1 (HSV-1) via intraperitoneal inoculation 12 weeks after transplantation. Allogeneic transplant recipients with graft-versus-host disease (GVHD) had significantly increased mortality from HSV-1 encephalitis, with deficiencies of both specific anti-HSV-1 antibody and total serum IgG2a. GVHD mice displayed a Th2 cytokine profile (increased interleukin-4 [IL-4] and decreased interferon-gamma) and decreased lipopolysaccharide (LPS) responses, suggesting that both T-cell and B-cell defects contributed to the impaired production of antibody. Because passive transfer of hyperimmune serum protected mice from HSV-1 infection, we hypothesized that CD40 ligand (CD40L), which induces B-cell maturation, would protect mice from HSV-1 infection. CD40L-treated GVHD mice showed elevated IgG2a levels and increased survival compared with vehicle-treated transplant recipients.

A role for transforming growth factor-beta1 in the increased pneumonitis in murine allogeneic bone marrow transplant recipients with graft-versus-host disease after pulmonary herpes simplex virus type 1 infection.

To gain further insights in the pathogenesis of herpesvirus pneumonia in allogeneic bone marrow transplant recipients, transplanted mice (B10.BR --> CBA) with graft-versus-host disease (GVHD) and control mice (transplanted mice without GVHD and normal CBA mice) were infected intranasally with herpes simplex virus type 1 (HSV-1). When compared with infected control mice, infected allogeneic transplant recipients with GVHD showed increased periluminal mononuclear cell infiltrates. However, infected allogeneic transplant recipients with GVHD showed lower virus content in the lung tissue than infected control mice. High concentrations of transforming growth factor-beta 1 (TGF-beta1) were detected in the bronchoalveolar lavage (BAL) fluid of mock-infected allogeneic transplant recipients with GVHD, which increased slightly after infection. Anti-TGF-beta treatment of allogeneic transplant recipients with GVHD significantly decreased the histological evidence of pneumonitis at day 4 after HSV-1 infection. We conclude that allogeneic transplant recipients with GVHD have (1) increased pneumonia, (2) highly elevated levels of TGF-beta1 in the BAL fluid, and (3) reduced pulmonary virus content after HSV-1 infection. Our data suggest that the newly recognized dysregulation of cytokine (TGF-beta1) production may be more important than the viral load for the increased severity of HSV-1 pneumonia in allogeneic transplant recipients with GVHD.

Suppression of herpes simplex virus type 1 (HSV-1)-induced pneumonia in mice by inhibition of inducible nitric oxide synthase (iNOS, NOS2).

Intranasal Herpes simplex virus type 1 (HSV-1) infection of mice caused pneumonia. Manifestations of the disease included: histological pneumonitis, pulmonary influx of lymphocytes, decreased pulmonary compliance, and decreased survival. Immunohistochemical staining demonstrated iNOS induction and the nitrotyrosine antigen in the lungs of infected, but not uninfected mice, suggesting that nitric oxide contributes to the development of pneumonia. To elucidate the role of nitric oxide in the pathogenesis of HSV-1 pneumonia, infected mice were treated either with the inhibitor of nitric oxide synthase activity, N(G)-monomethyl-L-arginine (L-NMMA), or, as a control, with PBS or D-NMMA. L-NMMA treatment decreased the histological evidence of pneumonia and reduced the bronchoalveolar lavage lymphocyte number to one-quarter of the total measured in control-treated mice. L-NMMA treatment significantly improved survival and pulmonary compliance of HSV-1-infected mice. Strikingly, the L-NMMA-mediated suppression of pneumonia occurred despite the presence of a 17-fold higher pulmonary viral titer. Taken together, these data demonstrated a previously unrecognized role of nitric oxide in HSV-1-induced pneumonia. Of note, suppression of pneumonia occurred despite higher pulmonary virus content; therefore, our data suggest that HSV-1 pneumonia is due to aspects of the inflammatory response rather than to direct viral cytopathic effects.

TCR-beta transgenic mice fail to mediate a GVHR due to defects of allorecognition and subsequent IL-2 generation.

All T cells of TCR-beta transgenic mice bear a single TCR-beta chain and consequently the diversity of the TCR may be reduced by as much as one million-fold. Despite this limited diversity, many measures of lymphocyte function in these mice are normal. We have previously demonstrated that lymphoid cells from TCR-beta mice are unable to mediate an intense graft-versus-host response (GVHR). In order to investigate the mechanism of this hyporesponsiveness, we studied in vivo allorecognition in diverse strains of TCR-beta mice. All tested strains of TCR-beta mice failed to mediate a substantial GVHR across multiple H-2 barriers. In addition, mixtures of cells from several strains of TCR-beta mice only generated mild GVHRs. Sensitive tests of in vitro allorecognition show that lymphoid cells from TCR-beta mice respond less vigorously to alloantigen as measured both by decreased proliferation and decreased IL-2 production in a MLR. In addition, cells from TCR-beta mice fail to use exogenous IL-2 appropriately in their response to alloantigen. We conclude that the fixed TCR-beta chain causes a defective response to alloantigen, which is measured as decreased IL-2 generation and utilization, and that this abnormality results in a decreased GVHR.

CpG island mapping of a mouse double-minute chromosome.

The development of double-minute chromosomes (DMs) and subsequent gene amplification are important genomic alterations resulting in increased oncogene expression in a variety of tumors. The molecular mechanisms mediating the development of these acentric extrachromosomal elements have not been completely defined. To elucidate the mechanisms involved in DM formation, we have developed strategies to map amplified circular DM DNA. In this study, we present a long-range restriction map of a 980-kb DM. A cell line cloned from mouse EMT-6 cells was developed by stepwise selection for resistance to methotrexate. This cloned cell line contains multiple copies of the 980-kb DM carrying the dihydrofolate reductase (DHFR) gene. A long-range restriction map was developed in which a hypomethylated CpG-rich region near the DHFR gene served as a landmark. This strategy was combined with plasmid-like analysis of ethidium bromide-stained pulsed-field gels and indicated that a single copy of the DHFR gene was located near a hypomethylated region containing SsII and NotI sites. At least 490 kb of this DM appears to be composed of unrearranged chromosomal DNA.

Phorbol ester regulation of terminal deoxynucleotidyl transferase, proliferation, and TcR alpha in a pre-T cell line.

Terminal deoxynucleotidyl transferase (TdT) is a template-independent DNA polymerase that is transiently expressed during the normal development of T and B lymphocytes. Phorbol 12-myristate 13-acetate (PMA) has been reported to induce maturation-like changes, including the loss of TdT, in many leukemic cell lines. We investigated the mechanism of TdT repression by PMA in an early thymocyte-like cell line, RPMI 8402. At a concentration of 8 nM, PMA caused both repression of TdT synthesis and arrest of proliferation. At greater concentrations of PMA, these same changes initially occurred, but then cell proliferation resumed, and TdT was reexpressed. At both 8 and 160 nM PMA, TdT biosynthesis and TdT mRNA became undetectable within 8 hours, while cell proliferation and DNA synthesis were not significantly reduced until 16 hours. Growth arrest induced by serum starvation did not result in a similar reduction of TdT RNA even after 48 hours. With 160 nM PMA, TdT mRNA could be detected again by 24 hours, and proliferation resumed. Transcription run-off assays indicated that TdT RNA synthesis ceased within 1 hour after exposure to both 8 and 160 nM PMA. T cell receptor alpha (TcR alpha) RNA was induced when TdT RNA was repressed. TcR beta RNA levels were unchanged, and TcR gamma RNA was up-regulated. TdT gene repression and modulation of cell proliferation as well as induction of TcR gene expression are normal events during intrathymic T cell maturation. This cell model provides a system for analyzing the molecular regulation of these significant developmental events.

Schistosomiasis in an American medical investigator.

A 42-year-old American male researcher contracted schistosomiasis from environmental sources in the course of his observations on human behavior in Upper Egypt. After a long asymptomatic period, he developed various symptoms and Schistosoma haematobium was found in a urine examination. After treatment with Metrifonate, urine examination became negative. However, abdominal pain persisted and most diagnostic tests were negative. Colonoscopic examination and biopsy of the mucosa revealed schistosomiasis. Treatment with Praziquantel was thoroughly effective in clearing the persistent Schistosoma haematobium infection. It is necessary to maintain a high index of suspicion in cases of potential schistosomiasis. The availability of nontoxic treatment is discussed.

Nonadrenergic inhibitory nervous system in human airways.

Human airways, from the middle of the trachea to the distal bronchi, were studied in vitro for the presence of inhibitory nerves. The tissue was obtained from operations and from recent autopsies. Electrical field stimulation of the tissues demonstrated cholinergic, excitatory nerves and their effect was blocked by atropine. Field stimulation of the tissues, in the presence of atropine, relaxed the smooth muscle even when the muscle was contracted by histamine. The field stimulation-induced relaxation was neither blocked nor modified by adrenergic blocking agents. Maximum relaxation of the bronchial muscle was obtained with a pulse duration of 1-2 ms, 70 V, and frequencies of 20 Hz and greater. The tracheal smooth muscle showed 85% of maximal relaxation with a frequency of 10 Hz. Tetrodotoxin, blocked the field stimulation-induced relaxation for pulse durations of 2 ms; this indicated that nerves were being stimulated. The airway system shows some of the characteristics of the nonadrenergic inhibitory system in the gastrointestinal tract and of the system reported in the guinea pig trachealis muscle. No evidence of adrenergic inhibitory fibers was found in the bronchial muscle with either pharmacological or histochemical techniques. These findings suggest that the nonadrenergic inhibitory system is the principal inhibitory system for the smooth muscle of human airways. We suggest that a defect in the airway system, such as that shown in the gastrointestinal tract, may be an explanation for the hyperreactive airways of asthma and chronic bronchitis.

Diagnostic procedures in sarcoidosis.

One hundred consecutive patients suspected of having sarcoidosis were examined by means of available diagnostic procedures and the results of the examinations were compared. While Kveim tests and/or lymphocyte transformation tests gave the most significant results in cases of less than two years' standing, a combination of these and organ biopsies is required for the diagnosis of cases of more than two years' duration.An interpretation of the immunological deviations observed in sarcoidosis is attempted on the basis of observations made on leukocyte cultures and on isolations of mycobacteriophages from patients with sarcoidosis.