[The seroprevalence of Mycoplasma bovis in lactating cows in Switzerland, particularly in the republic and canton of Jura]. / Etude sur la séroprévalence de Mycoplasma bovis chez la vache laitière en Suisse, en particulier dans la République et Canton du Jura.

Sporadic cases of infection with Mycoplasma bovis have been observed in Switzerland since 1983. However, five severe outbreaks of endemic mastitis in a geographically distinct, small region (Canton du Jura) during the period 1995 to 1997 prompted the present investigation on the seroprevalence of infection with M. bovis among milking cows in Switzerland. A commercially prepared indirect enzyme immunoassay was used. Among a stratified random sample of 118 herds of milking cows in Switzerland, at least one positive animal was detected in 56 (47%) of the herds, whereas 6.1% of the 1816 individual animals tested positive. An epidemiological study was performed in the Canton du Jura region among 51 herds in order to assess the importance of management factors in the spread of M. bovis infection. The herd-level prevalence was 78%, and the seroprevalence at the level of the 1354 individual animals tested was 13.4%. A multivariate analysis of possible risk factors showed purchase of animals to be the only variable significantly associated with serological status of the herd with an "odds ratio" of 10.8.

Angiogénesis inducida por colágena polivinilpirrolidona y heparina en el músculo isquémico / Angiogenesis induced by polivinilpirrolidone collagen and heparin in the ischemic muscle

Estudio de investigación experimental, prospectivo y comparativo, con el objeto de evaluar los efectos de la aplicación exógena de colágena tipo I, Polivinilpirrolidona (PVP) y heparina, en túneles musculares fibrocolágenos, en la extremidad isquémica de la rata, para inducir neovascularización o angiogénesis. Se usó un modelo de isquemia en la extremidad posterior derecha de 40 ratas Wistar en dos tiempos. 1º Ligadura de la arteria iliaca común vía abdominal y colocación de una protesis de silasticpoliéster en el músculo gracilis para la generación de un túnel fibrocolágeno. 2º Ocho semanas después, exposición del paquete vascular femoral, ligadura de esta arteria, localización y extracción de la prótesis, perforación y lavado del túnel fibrocolágeno y aplicación de sustancias. En el grupo I se aplicó solución fisiológica, en el grupo II colágena tipo I con PVP, en el grupo III heparina sódica y grupo IV colágena tipo I con (PVP) y heparina sódica. Para la valoración se llevó a cabo angiografía de las extremidades tratadas, cuantificando el número de intersecciones en una superficie milimétrica de 50 x 50 mm. El mayor número de intersecciones se obtuvo en el grupo IV con una medida de 20.22 contra una media de 13.5 intersecciones en el grupo I (control con sol. fisiológica) = p de 0.14 mediante el análisis de varianza para comparar dos grupos (ANOVA). El estudio demuestra mayor angiogénesis en el músculo isquemico de la rata, si se aplica colágena tipo I con (PVP) y heparina

Evidence for interleukin-1 beta being a necessary but not sufficient co-stimulatory signal in monocyte-dependent anti-CD3-mediated T-cell triggering.

T-cell activation by CD3-specific antibodies is either monocyte independent or monocyte mediated, depending on the fine specificity and mode of presentation of anti-CD3. Monocyte-independent activation occurs when T cells encounter surface-bound antibody at high density, thereby mediating interleukin-2 (IL-2) production. Monocyte-dependent activation occurs upon bipolar binding of anti-CD3 to CD3 of T cells and to Fc receptors of accessory cells (monocytes). We addressed the role of interleukin-1 (IL-1) as a co-stimulatory signal in monocyte-dependent anti-CD3-mediated T-cell proliferation by using specific and anti-IL-1 subtype antibodies and IL-1 receptor antagonist (IL-1ra). IL-1ra blocked proliferation of mononuclear cells (MNC) induced by fluid-phase anti-CD3, and proliferation of nylon wool-purified cells (NWPC; < 1% monocytes) exposed to low-density, but not high-density, anti-CD3 coats. Stimulation of MNC by fluid-phase anti-CD3 and of NWPC by low-density anti-CD3 coats could both be blocked by anti-IL-1 beta, but not by anti-IL-1 alpha, although the latter efficiently blocked IL-1 alpha-mediated thymocyte co-stimulation. Neither the addition of IL-1 beta (given alone or combined with IL-6 and/or IL-1 alpha) nor anti-CD3-independent, LPS-induced cytokine induction in monocytes provided the co-stimulatory signal(s) for anti-CD3-triggered T cells in the absence of bipolar anti-CD3 binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Generation and functional characterization of ovine bone marrow-derived macrophages.

A method for the culturing and propagation of ovine bone marrow-derived macrophages (BMM) in vitro is described. Bone marrow cells from sterna of freshly slaughtered sheep were cultured in hydrophobic (teflon foil) bags in the presence of high serum concentrations (20% autologous serum and 20% fetal calf serum). During an 18 day culture period in the absence of added conditioned medium, and without medium change, a strong enrichment of mononuclear phagocytes was achieved. Whereas the number of macrophages increased four to fivefold during this time, granulocytes, lymphoid cells, stem cells and undifferentiated progenitor cells were reduced to less than 3% of their numbers at Day 0. This resulted in BMM populations of 94 +/- 3% purity. These cells had morphological and histochemical characteristics of differentiated macrophages, and they performed functions similar to those of non-activated, unprimed human monocyte-derived macrophages. Thus, they avidly ingested erythrocytes coated with IgG of heterologous or homologous origin. They expressed a modest level of procoagulant activity, but upon triggering with lipopolysaccharide (LPS), a marked increase in cell-associated procoagulant activity was observed. LPS triggering promoted the secretion of interleukin-1, as evidenced by measurement of murine thymocyte costimulatory activity, and transforming growth factor-beta. Using the mouse L929 cell cytotoxicity assay as an indication of tumor necrosis factor (TNF) activity, no TNF activity was detected in the same supernatants, a result possibly due to species restriction. BMM generated low levels of O2- upon triggering with phorbol 12-myristate 13-acetate (PMA). On the other hand, no O2- production was observed upon stimulation with zymosan opsonized with ovine or human serum. Using luminol-enhanced chemiluminescence (CL) as a more sensitive indicator of an oxidative burst, both PMA or zymosan were able to trigger CL, but the response was subject to partial inhibition by sodium azide, an inhibitor of myeloperoxidase. This points to non-macrophage cells contributing also to the CL response, and is consistent with the view that unprimed BMM elicit a low oxidative burst upon triggering with strong inducers of a burst. Our functional characterization now allows us to apply priming and activation protocols and to relate their effect to functional alterations.

IGG-stimulated and LPS-stimulated monocytes elaborate transforming growth factor type beta (TGF-beta) in active form.

Mononuclear cells (MNC) stimulated either with lipopolysaccharide (LPS) or with surface-adsorbed IgG elaborated significant amounts of tumor necrosis factor (TNF) bioactivity, as well as immunoenzymatically detectable TNF-alpha and interleukin-1 beta. (IL1-beta). In contrast, IgG-stimulated cells released little IL1 bioactivity, but released an IL1 inhibitor, as determined by the thymocyte costimulatory assay (LAF assay). This inhibition was not due to an inhibitory effect of cyclooxygenase products, e.g. prostaglandin-E2 in the LAF assay. In contrast, antibodies against transforming growth factor type beta (TGF-beta), which is an important inhibitor of the LAF assay, augmented the LAF activity of supernatants from LPS-stimulated and IgG-stimulated MNC. Anti-TGF-beta-modulated LAF inhibition was enhanced by acid treatment of supernatants from mononuclear cells, but not of those from purified monocytes. Antibody blocking experiments point for the first time to a TGF-beta species other than type 1 as a monocyte-derived TGF-beta activity. Thus, TGF-beta released in active form from monocytes may be the more important antagonist of IL1 than cyclooxygenase-derived mediators. It implies that the LAF assay, in the absence of anti-TGF-beta antibodies, is an inadequate indicator of IL1 activity.

Cytokine induction in human mononuclear cells stimulated by IgG-coated culture surfaces and by IgG for infusion.

The effect of IgG on cytokine production by human mononuclear cells (MNC) was studied. Tumor necrosis factor-alpha (TNF) was determined both by bioassay and by immunoassay. Interleukin-1 (IL1) was measured by a thymocyte costimulator assay, which was shown to be completely inhibitable by polyclonal anti-IL1. Precautions were taken to avoid inadvertent exposure of the studied cells to endotoxin. In a first model, TNF and IL1 production by adherent MNC in IgG-coated cluster plates were determined. IgG induced a strong TNF response, usually leveling off after 6 hr, and was comparable in kinetics and magnitude with an LPS-induced response. The thymocyte co-stimulatory activity response was relatively weak and peaked at 6 hr. In contrast, LPS-induced co-stimulatory activity production steadily increased over 24 hr. In a second model, MNC in suspension cultures containing autologous serum were exposed to IgG for intravenous use (IgG-IV). Cells exposed to IgG-IV produced higher amounts of cytokines than control counterparts and were primed for enhanced production of cytokines upon a second, unrelated stimulus. This implies that the effect of IgG-IV on suspended MNC resembles that of surface-adsorbed IgG and raises the possibility that cytokine release is an integral part of the mechanism of action of infused IgG. Evidence is presented suggesting that both surface IgG and IgG-IV act directly on monocytes, in a Fc-dependent manner.

The triggering of fibrinogen receptors on mononuclear phagocytes of healthy subjects and of a thrombasthenia Glanzmann patient promotes the generation of reactive oxygen species.

The interaction of human fibrinogen (Fg) with homologous mononuclear phagocytes was investigated. Using a radioligand binding test, no evidence for high-affinity binding of either monomeric Fg, of the fibrin fragment E, or of radiolabelled Gly-Pro-Arg-Pro(-Try) to mononuclear phagocytes and myelomonocytic cell lines could be obtained, although commercial labelled Fg specifically bound to monocytes (MO), macrophages (M phi), U937 and HL60 cells. MO pretreated with either commercial or monomeric Fg and washed showed an oxidative burst upon treatment with anti-Fg antibodies, as evidenced by chemiluminescence (CL) measurement in the presence of luminol. The reaction depended on the Fg concentration used for pre-incubation, was divalent cation-independent and was inversely related to the time for which Fg was allowed to dissociate from the cell surface. Induction of the CL response required specific divalent antibodies, but not an intact Fc portion. MO pre-treated with fibronectin (Fn), washed and treated with anti-Fn antibodies exhibited no CL response. MO from a patient with thrombasthenia Glanzmann showed a similar reaction upon pre-incubation with Fg and stimulation with antibody. CL was also triggered by exposure of MO to surface-adsorbed Fg. The response was smaller than that induced by equivalent amounts of IgG, but was larger than that promoted by Fn. Pre-treatment of MO with ADP, fMLP or LPS did not enhance CL induced by surface-adsorbed Fg. Our results suggest that unstimulated mononuclear phagocytes of healthy subjects and of patients lacking the Fg receptors on platelets have receptors that bind the C-gamma-terminus of fibrin(ogen) with relatively low affinity, and that crosslinking of these receptors by surface-bound ligand promotes an oxidative burst but fails to induce cytokine secretion.