Interindividual differences in degradation of sodium monofluorophosphate by saliva in relation to oral health status

The enzymatic degradation of sodium monofluorophosphate by whole saliva in patients with differing oral health status was compared Ten patients each with good or poor oral health were selected. Assessment of oral health status included indices of the amount of dental plaque, caries experience and counts of Streptococcus mutans and lactobacilli. Whole-saliva samples were collected under standardized conditions and monofluorophosphatase (MFPase) activity was measured in 2-ml saliva samples during 2 h of incubation at 37 C with 1 ml of monofluorophosphate solution (equivalent 31.5 mmol/1 F). MFPase activity was found in all the saliva samples. The values ranged from 0.6 to 17.8 nmol F/ml saliva per min. High MFPase activities correlated well with large amounts of plaque with the D component of the DMFT index and with high counts of salivary S. mutans and lactobacilli. The results show a wide range of MFPase activity in individuals and a statistically significant correlation (p < 0.05) between high MFPase activity and poor oral health status.

Diffusion characteristics of placental preparations affect the digoxin passage across the isolated placental lobule

Our aim was to evaluate the isolated placental lobule to study maternofetal transplacental digoxin transfer and accumulation in placental tissue in vitro. Digoxin passage across the isolated lobule of 10 human placentas was calculated from repeated fetal and maternal perfusate samples, and placental tissue digoxin concentrations were measured at the end of the experiments. To determine the degree of overlap of the fetal and the maternal circulation, the antipyrine clearance was used. Digoxin disappearance from the maternal circuit was not significantly affected by the degree of overlap. In contrast, the increase of digoxin in the fetal compartment was significantly higher in "well-perfused" placentas (antipyrine clearance > 1.60 ml/min; n = 5) than in "malperfused" placentas (antipyrine clearance < 1.50 ml/min; n = 5) (end-feto to initial maternal digoxin ratio 0.44 +/- 0.08 vs. 0.30 +/- 0.08; p < 0.05), whilst the accumulation in placental tissue was higher in the latter group (0.45 +/- 0.07 vs. 0.62 +/- 0.10 ng/mg protein; p < 0.05). We conclude that the isolated placental lobule is suitable to quantify transplacental digoxin transfer in vitro, but the diffusion characteristics of each preparation have to be considered.

Partial inhibition of AT-EAE by an antibody to ICAM-1: clinico-histological and MRI studies

The role of quantitative proton magnetic resonance imaging (MRI) for the evaluation of immunopathological lesions in the CNS was studied in adoptively transferred experimental allergic encephalomyelitis (AT-EAE). We utilized a recently established treatment model, inhibition of the cell adhesion molecule ICAM-1 by the monoclonal antibody 1A-29. The animals were scanned on days 3, 5 and 7 after injection of encephalitogenic T-cells, before and after bolus injection of Gd-DTPA by performing T1-measurements to assess the integrity of the blood-brain barrier (BBB). On day 7, immunohistochemistry was performed looking for T-cells, activated macrophages, and albumin staining. There was clinical evidence of partial inhibition of AT-EAE in rats treated with antibodies against ICAM-1. This finding was in line with a significantly reduced number of T-cells in the medulla. However, the number of activated macrophages and the distribution of albumin did not differ from untreated AT-EAE animals. The histological findings are in agreement with the MRI data before and after Gd-DTPA injection which were similar in treated and untreated AT-EAE rats on day 3 and 5. On day 7 after Gd-DTPA injection there was evidence of a delayed breakdown of the BBB in the treated rats. The observation of a dissociation of clinical and MRI findings, especially evidence of Gd-enhancement despite clinical improvement, may be important in the context of interpreting MRI studies in MS patients in treatment trials.

Preventive but not therapeutic application of Rolipram ameliorates experimental autoimmune encephalomyelitis in Lewis rats

Experimental autoimmune encephalomyelitis (EAE) in Lewis rats, an animal model mimicking some aspects of multiple sclerosis, was treated with the type IV-specific phosphodiesterase inhibitor Rolipram. Actively induced EAE evoked by immunization with myelin basic protein (MBP) in complete Freund's adjuvant was delayed but only slightly ameliorated in its maximal severity by preventive treatment with Rolipram (2 x 3 mg/kg per day) starting on the day of immunization. Therapeutic administration of Rolipram (2 x 5 mg/kg per day) was begun within hours after onset of first clinical signs of EAE but could not modify the further course of the disease. Both doses had significant side effects. Injection of 5 mg Rolipram/kg provoked transient slackening and unsteady gait while chronic application of 6 mg/kg/day strongly accelerated the weight gain in adolescent rats. EAE adoptively transferred by injection of encephalitogenic T line blasts was shortened and significantly suppressed in its severity by application of Rolipram (2 x 5 mg/kg per day) starting on the day of cell transfer. In corresponding lumbar spinal cord sections density of inflammatory infiltration by T cells and macrophages was reduced. Rolipram did not prevent generation of an antigen-specific immune response in vivo. In vitro the drug inconsistently inhibited MBP-induced activation of encephalitogenic T cells. TNF-alpha secretion by encephalitogenic T cells was limited only when T cell proliferation was also affected. In contrast, TNF-alpha production by LPS-activated macrophages was consistently and markedly suppressed by Rolipram. However, since the encephalitogenic T line cells produced at least 100 times more TNF-alpha than the same number of Rolipram-sensitive macrophages, the impact of Rolipram on the total amount of TNF-alpha synthesized in EAE may be limited. Together with our histological findings, the data suggest that relevant immunosuppressive mechanisms of Rolipram may be the inhibition of migration of leukocytes into the central nervous system and to some extent its inhibitory effect on T cell proliferation and macrophage activity. The downregulatory effects of Rolipram may be partially counteracted by its augmenting impact on the production of nitric oxide by macrophages.

T cell directed immunotherapy of inflammatory demyelination in the peripheral nervous system. Potent suppression of the effector phase of experimental autoimmune neuritis by anti-CD2 antibodies

Experimental autoimmune neuritis (EAN) of Lewis rats, an inflammatory demyelinating neuropathy and model of the human Guillain-Barré syndrome (GBS), was used to evaluate the novel T cell directed immunotherapy with the anti-CD2 monoclonal antibody (mAb) OX34. Clinical signs of EAN actively induced by immunization with bovine peripheral nerve myelin in complete Freund's adjuvant (CFA) were totally prevented or markedly suppressed by preventative injections of OX34 starting 8 days post-immunization (p.i.). Moreover, therapeutic application of the mAb beginning on the day of first clinical signs of EAN markedly inhibited progression of disease. Electrophysiological and histological investigation of sciatic nerves 17 and 18 days p.i. respectively, also revealed an inhibitory effect of OX34 on EAN-associated functional and morphological nerve damage. Similarly, therapeutic injections of OX34 after onset of EAN actively induced by immunization with a neuritogenic peptide of the P2 protein completely halted further deterioration of clinical disease. Finally, clinical, electrophysiological and histological signs of adoptive transfer EAN mediated by injection of neuritogenic T helper line cells were prevented or strongly suppressed by OX34-application on the day of cell transfer and 4 days later, underlying the impact of the mAb on the effector phase of the disease. Since the anti-CD2 mAb did not exert its effect by inhibition of T cell activation, induction of anergy, modulation of CD2 antigens, or by T cell depletion, we assume that it may affect migration of T lymphocytes across the blood-nerve barrier. The immediate and marked suppression of ongoing EAN by the mAb lead to the recommendation of anti-CD2 mAbs as candidates for T cell directed immunotherapy of the GBS.

Effector mechanisms in demyelinating neuropathies

While the cause of the immune-mediated neuropathies (Guillain-Barr-e syndrome, GBS; CIDP; multi-focal motor neuropathy and paraproteinemic neuropathies) remains elusive considerable progress has been made in delineating the effector mechanisms that underlie myelin destruction. In GBS circulating antibodies to glycolipids possibly precipitated by an antecedent Campylobacter jejuni infection can be detected with high frequency. These antibodies may interfere with neuromuscular transmission and eventuate myelin damage by activating the complement system, providing for the generation of chemotactically active split products C3a and C5a, the opsonin C3b, and assembly of the membrane attack complex. Such antibodies may also, via binding to the Fc receptor, target macrophages to the myelin sheath. Corroborative evidence for a crucial pathogenic role of antibody-mediated complement activation is also available for the MAG-associated neuropathies. Macrophages as decisive effector cells of myelin damage may also act by releasing injurious molecules such as oxygen radicals, nitric oxide metabolites, proteases, eicosanoids and cytokines. Demyelinative as well as degenerative actions have been described for the cytokines TNF-alpha and lymphotoxin. Increased understanding of the effector mechanisms underlying demyelination may aid in developing more efficacious treatments for this group of neuropathies.

Comparison of the substrate specificities of cAMP-dependent protein kinase from bovine heart and Ascaris suum muscle

The catalytic subunits of cAMP-dependent protein kinases (protein kinase A) from bovine heart and Ascaris suum muscle exhibit only 48% sequence identity and show quantitative differences in substrate specificity. These differences were not obvious at the level of short synthetic substrate peptides but were distinct for some protein substrates. Phosphofructokinase from Ascaris, a physiological substrate, was a better substrate for the protein kinase from the nematode in comparison to the mammalian protein kinase due to a 10-fold lower Michaelis constant. Selective phosphorylation by the two kinases was also observed with some in vitro substrates. In addition, quantitative differences in the interactions between R- and C-subunits from Ascaris and bovine heart were observed. However, several synthetic peptides whose sequence reflected the phosphorylation site of Ascaris suum phosphofructokinase (AKGRSDS*IV), or variations of it, were phosphorylated with the same efficiency by both protein kinases. Based on the data the following are concluded: (1) In agreement with the conservation of structure in the catalytic cleft, the recognition of substrates by protein kinases from phylogenetically distant organisms exhibits similarity. (2) Non-conserved parts of the surface of the protein kinase molecule may contribute to binding of protein substrates and thus to selective recognition.

Cicutoxin from Cicuta virosa--a new and potent potassium channel blocker in T lymphocytes

The effect of cicutoxin, the poisonous principle of the genus Cicuta, on K+ currents of activated T lymphocytes was investigated using the patch clamp technique. Cicutoxin produced a dose-dependent [5 x 10(-6) to 7 x 10(-5) mol/l] and completely reversible block of K+ currents with an EC50 of 1.8 x 10(-5) mol/l. A maximum block of 71% was achieved with cicutoxin at a concentration of 7 x 10(-5) mol/l. Since previous studies have shown that T lymphocyte proliferation is associated with K+ currents, the effect of cicutoxin on T lymphocyte proliferation was studied by means of 3H-thymidine uptake assays. At noncytotoxic concentrations [10(-7) to 5 x 10(-5) mol/l] cicutoxin reduced the 3H-thymidine incorporation dose-dependently. In conclusion, cicutoxin is a potent K+ current blocker which inhibits K+ channel-dependent proliferation of naive and memory T lymphocytes.

In vivo MRI and its histological correlates in acute adoptive transfer experimental allergic encephalomyelitis. Quantification of inflammation and oedema

In vivo proton MRI was carried out on a 7 Tesla system at 2-3 day intervals over 10 days in rats with adoptive transfer experimental allergic encephalomyelitis (AT-EAE), an animal model of some aspects of multiple sclerosis. In order to assess the integrity of the blood-brain barrier (BBB), MRI was performed by acquiring quantitative MR-relaxation time T1 images of the AT-EAE rat brain before and after i.v. injection gadolinium-diethylene triaminepentaacetic acid (Gd-DTPA) using an ultrafast MRI technique. The MRI findings were compared with the immunohistochemical stain of T cells, macrophages and albumin and, in addition, apoptosis of T cells was assessed using in situ nick translation (ISNT). Prior to injection of Gd-DTPA, an increase of T1 times in the brain of the AT-EAE rats was observed, which paralleled the time course of albumin in histological sections. These were MRI findings observed well before the onset of major cellular infiltration and before the onset of clinical signs. After i.v. injection of Gd-DTPA the observed decrease of T1 times paralleled macrophage activation, and less closely T-cell infiltration. Our results provide evidence that using MRI, it is possible to assess quantitatively the breach of the BBB and to distinguish in vivo between two components of the early phase of the lesion, inflammatory infiltrates and vasogenic oedema.

Transforming growth factor-beta 1 in experimental autoimmune neuritis. Cellular localization and time course

Experimental autoimmune neuritis (EAN) is a monophasic inflammatory disorder of the peripheral nervous system that resolves spontaneously by molecular mechanisms as yet unknown. We have investigated whether the immunosuppressive cytokine transforming growth factor-beta 1 (TGF-beta 1) might be endogenously expressed in the peripheral nervous system of Lewis rats with actively induced and adoptive transfer EAN. TGF-beta 1 mRNA was upregulated to high levels in sensory and motor roots, spinal ganglia, and sciatic nerve as revealed by quantitative Northern blot analysis and in situ hybridization histochemistry, with peak levels just preceding the first signs of clinical recovery. TGF-beta 1 mRNA was localized to scattered round cells and dense cellular infiltrates, but only rarely to Schwann cell profiles. Double labeling studies revealed macrophages and subpopulations of T cells as the major cellular source of TGF-beta 1 mRNA. TGF-beta 1 protein was visualized immunocytochemically and localized to infiltrating mononuclear cells with peak expression around the same time as mRNA, in addition to some constitutive expression in axons and Schwann cells. Our studies suggest that the spontaneous recovery observed in Lewis rat EAN might be mediated by the endogenous elaboration of TGF-beta 1 within the peripheral nerve, and that macrophages might control their own cytotoxicity by expressing TGF-beta 1.

Digoxin transfer across the isolated placenta is influenced by maternal and fetal albumin concentrations

The aim of this study was to evaluate the influence of different maternal and fetal albumin concentrations on the transplacental transfer and the placental tissue accumulation of digoxin. Digoxin passage across the isolated lobules of 15 human placentae was calculated from repeated fetal and maternal perfusate samples, and placental tissue digoxin concentrations were measured at the end of the experiments. Metildigoxin (Lanitop) was added to the maternal medium at a concentration of 5.70 +/- 0.73 ng mL-1, and maternal and fetal perfusate albumin (BSA) concentrations were kept equal either at a high concentration of 21 g L-1 (Group I; n = 5) or at a low concentration of 3 g L-1 (Group III; n = 5), or differed with a materno-fetal gradient of 21:3 g L-1 (Group II; n = 5). In the experiments with low maternal albumin concentrations (Group III), digoxin concentrations in the maternal circuit decreased to 3.56 ng mL-1, whereas digoxin concentrations in the fetal circuit reached 2.59 ng mL-1 over a 3-h period. With maternal BSA concentrations of 21 g L-1 (Group I and Group II), the decrease in digoxin concentration in the maternal circuit was lower (P < 0.05), and digoxin tissue concentrations at the end of the experiments were smaller (0.45 +/- 0.07 and 0.42 +/- 0.03 v. 0.82 +/- 0.32 ng mg-1 protein, Group I and Group II v. Group III respectively; P < 0.05). Comparing only those lobules with similar high concentrations of maternal protein, fetal BSA concentrations of 21 g L-1 resulted in a greater increase in digoxin concentrations in the fetal circuit (end-feto to initial-maternal digoxin concentrations of 0.44 +/- 0.08 v. 0.37 +/- 0.04 ng mg-1 protein (Group I v. Group II respectively), although this was not significant. The data suggest that maternal and fetal serum albumin concentrations may have an influence on transplacental digoxin transfer, and this should be considered when treating fetuses with cardiac disease transplacentally with glycosides.

T cell antigenic and neuritogenic activity of recombinant human peripheral myelin P2 protein

The major neuritogenic protein of peripheral nerve myelin is the P2 protein. Human P2 is a candidate autoantigen in inflammatory demyelinating diseases of the peripheral nervous system. Since human P2 is not readily available, we produced full-length recombinant human P2 protein (rhP2) in Escherichia coli. RhP2 was recognized by neuritogenic rat T cell lines and induced experimental autoimmune neuritis in Lewis rats. Production of rhP2 allowed the generation of human T cell lines reactive to the autologous protein. Studies of human T cell autoreactivity as well as efforts to use hP2 as a tolerogen will be facilitated by the large-scale expression of rhP2.

Soluble complement receptor type 1 inhibits experimental autoimmune neuritis in Lewis rats

Experimental autoimmune neuritis (EAN) in Lewis rats induced by immunization with bovine peripheral nerve myelin in complete Freund's adjuvant is an animal model of the human Guillain-Barré syndrome. In this study myelin-induced EAN was treated with 30 mg/kg per day human soluble complement receptor type 1 (sCR1) beginning on day 8 post immunization (p.i.). Clinical signs of disease were markedly suppressed by application of sCR1 and none of eight treated animals but seven of nine control rats developed paraparesis. Electrophysiologic examination of sciatic nerve function 13 days p.i. revealed faster nerve conduction velocities and significantly higher compound muscle action potentials in sCR1-injected animals. In sections of sciatic nerves acquired 16 days p.i. extended demyelination and axonal degeneration was prevented by treatment with sCR1 in vivo. Our findings underscore the functional importance of complement during inflammatory demyelination in the peripheral nervous system and suggest sCR1 as a potential therapeutic approach in these diseases.

Costimulation requirement for AP-1 and NF-kappa B transcription factor activation in T cells

The transcriptional activity of the IL-2 promoter requires T-cell costimulation delivered by the TCR and the auxiliary receptor CD28. Several transcription factors participate in IL-2 promoter activation, among which are AP-1-like factors and NF-kappa B. Protein phosphorylation has an important role in the regulation of these two factors: (1) it induces the transactivating capacity of the AP-1 protein c-Jun; and (2) it is involved in the release of the cytoplasmic inhibitor, I kappa B, from NF-kappa B, allowing translocation of the latter into the nucleus. We have recently shown that both phosphorylation processes require T-cell costimulation. Furthermore, in activated T cells, the kinetics of the two phosphorylation events are essentially similar. According to our results, however, the kinases responsible for the two processes are distinct entities. Whereas TPCK inhibits phosphorylation of I kappa B and, consequently, activation of NF-kappa B, it markedly enhances the activity of JNK, the MAP kinase-related kinase that phosphorylates the transactivation domain of c-Jun. We, therefore, propose the activation scheme presented in FIGURE 3 for T-cell costimulation. Costimulation results in the activation of a signaling pathway that leads to the simultaneous induction of the two transcription factors, AP-1 and NF-kappa B. Integration of the signals generated by TCR and CD28 engagement occurs along this pathway, which then bifurcates to induce I kappa B phosphorylation and NF-kappa B activation on the one hand, and JNK activation and c-Jun phosphorylation on the other. We are currently engaged in defining where the two signals integrate along the AP-1/NF-kappa B pathway.

The catalytic subunit of cAMP-dependent protein kinase from Ascaris suum. The cloning and structure of a novel subtype of protein kinase A

A complete cDNA clone encoding the catalytic subunit of cAMP-dependent protein kinase of Ascaris suum was constructed from two overlapping partial clones. The encoded sequence of 337 amino acids is 48% identical with the sequence of mouse C alpha subunit. Approximately the same low similarity was found with the sequence of the C subunit from another nematode, Caenorhabditis elegans. The N-terminal 14 amino acids and the myristoylation site of the mammalian protein are not contained in the enzyme from Ascaris. Two cysteines (Cys33 and Cys319) replace a basic residue in the N-terminal region and an acidic amino acid near the C-terminus which are conserved in all known C subunits from other sources. The substitutions provide the possibility of disulfide bridge formation between the N-terminal and C-terminal parts of the protein. There is strong evidence that a single gene encodes cAMP-dependent protein kinase in Ascaris. Modelling of the sequence into the coordinates of the X-ray structure of the mammalian enzyme suggest a high degree of conservation in the three-dimensional structure. However, structural variations occur at the surface of the protein near the catalytic cleft and are likely to account for the variations in substrate specificity previously observed between the purified protein kinase from Ascaris [Thalhofer, H. P., Daum, G., Harris, B. G. & Hofer, H. W. (1988) J. Biol. Chem. 263, 952-957] and the mammalian enzyme.

A new data model for biological classification

In the domain of biological classification, classifications are performed hierarchically. There are no standard classifications which are unanimously accepted by the community of each domain; many different interacting views of classification exist about the same data, and the discovery of new data results in changes to the existing classification. Even a single individual may change his or her own classification of a particular group. Since multiple classification views interact, they are semantically related. It is difficult to model this kind of dynamically evolving and semantically interacting classification system using traditional data models, which lack the structural flexibility necessary to support dynamic views of hierarchic classifications, and cannot properly capture the history of these complex interactions. We have developed a new data model which is suitable for supporting semantically interacting dynamic views of hierarchic biological classifications. On the basis of our new data model we have developed a prototype database system called HICLAS (HIerarchical CLAssification System); its domain is plant taxonomy. HICLAS is available through the Internet and an X-window interface has been implemented to support queries to classification data.

How cytokines control immunoglobulin class switching

B lymphocytes can alter the class of antibody they produce by immunoglobulin class switch recombination. This recombination is targeted by distinct cytokines to particular switch regions. Prior to switch recombination, the same cytokines induce transcription through the targeted switch regions and generate IH "switch" transcripts. To show whether the two events are functionally related, we have replaced the endogenous interleukin-4 (IL-4) dependent promoter of murine I gamma 1 switch transcripts by an heterologous promoter, the human metallothionein IIA (hMT) promoter. Indeed, switch recombination can be targeted to IgG1 by the hMT promoter. In mutant mice, which cannot generate processed switch transcripts, switch recombination cannot be targeted to IgG1 by the hMT promoter. Thus, IL-4 targets switch recombination to IgG1 by induction of processed switch transcripts.

Macrophages in T cell line-mediated, demyelinating, and chronic relapsing experimental autoimmune encephalomyelitis in Lewis rats

About 50% of the mononuclear cells in the perivascular lesions in the central nervous system (CNS) of rats suffering from experimental allergic encephalomyelitis (EAE) are blood-borne macrophages. In this study we investigated the role of these macrophages in different variants of EAE, using a liposome-mediated macrophage depletion technique. Intravenously injected liposomes containing dichloromethylene diphosphonate (Cl2MDP) are ingested by macrophages and cause temporary and selective elimination of these cells. Macrophage depletion during EAE induced by a T cell line specific for myelin basic protein (MBP; T cell-EAE) suppresses development of neurological signs of EAE. T cell-EAE with pronounced demyelination as induced by an additionally injected MoAb directed against myelin oligodendrocyte glycoprotein (MOG) was also significantly ameliorated after macrophage depletion. During chronic relapsing EAE (CR-EAE) the occurrence of relapses was prevented or suppressed, provided that the liposomes were injected before the initiation of a putative relapse. A chronic progressive course of CR-EAE was not modified by Cl2MDP containing liposome treatment. Histologic examination of the CNS of liposome-treated animals confirmed decreased infiltration of macrophages into the parenchyma in the rats with T cell and AD-EAE, whereas T cells were still present.

Suppression of experimental autoimmune encephalomyelitis in Lewis rats by antibodies against CD2

The immunotherapeutic potential of three anti-rat CD2 monoclonal antibodies (mAb) (OX34, OX54, OX55) and the combination of OX54 with OX55 was tested in Lewis rat experimental autoimmune encephalomyelitis (EAE). In actively induced EAE, a single injection of OX34 2 days before immunization with myelin basic protein (MBP) in complete Freund's adjuvant (CFA) completely prevented or greatly attenuated EAE in all animals. Injection of OX54 acted moderately suppressive while OX55 or OX54/55 did not affect disease severity. Abrogation of EAE by OX34 was not restricted to its application before immunization. Therapeutic administration of all three mAb and the Ab combination from onset of first clinical signs efficiently blocked progression of disease and prevented all animals from developing hind limb paresis. In adoptive transfer EAE induced with in vitro activated cells of an encephalitogenic T helper line, clinical and histological signs were completely prevented by injection of OX34 on the day of cell transfer and 4 days later, underlining the strong impact of anti-CD2 mAb on the effector phase of disease. Immunocytofluorometric analysis of peripheral blood lymphocytes after a single Ab injection demonstrated that all mAb induced a variable degree of transient reduction in T cell numbers and modulation of CD2 antigens. In contrast to the other mAb, OX34 persisted on lymphocytes for at least 11 days, which may explain its unique suppressive effect on EAE after a single injection before immunization. The assumption that prophylactic administration of OX34 also inhibits MBP-induced EAE, due to persistence into the effector phase, was substantiated by the finding that none of the mAb prevented generation of an antigen-specific cellular response in MBP/CFA-immunized animals. Since none of the Ab induced T cell unresponsiveness or inhibited T cell activation by antigen- or Ab-mediated stimulation of the T cell receptor, we suggest that their marked action on the effector phase of EAE may rely on inhibition of T cell infiltration into the central nervous system. The demonstrated efficacy of these anti-CD2 mAb in EAE suggests a potential therapeutic role that may be equal to that of anti-CD4 or anti-T cell receptor Ab.

Administration of nitric oxide synthase inhibitors in experimental autoimmune neuritis and experimental autoimmune encephalomyelitis

The nitric oxide (NO) synthase pathway is activated during experimental autoimmune inflammation of the central nervous system, and administration of aminoguanidine, an inhibitor of the cytokine-inducible NO synthase (NOS), ameliorated the disease course of autoimmune encephalomyelitis in the SJL mouse. We studied the role of nitric oxide synthase (NOS) in the pathogenesis of experimental autoimmune neuritis (EAN) and experimental autoimmune encephalomyelitis (EAE) in the Lewis rat. NG-L-monomethyl-arginine (L-NMMA), a competitive inhibitor of NOS, partially suppressed T cell line-mediated EAN, but not myelin-induced EAN, myelin basic protein (MBP)-induced EAE, or T cell line-mediated EAE. Aminoguanidine (AG), a selective inhibitor of the cytokine-inducible NOS, enhanced MBP-induced EAE, but had no significant effects on myelin-induced EAN. Two other NOS inhibitors, nitro-arginine methyl-ester and N-nitro arginine, had only little or no effects in EAN and EAE. The administration of NOS inhibitors showed some striking effects in EAN and EAE, but the observed diversity of actions points to a much more complex role of the NO pathway than previously suggested.

Activated T cells of nonneural specificity open the blood-nerve barrier to circulating antibody

Recent studies from our laboratory and by other investigators have shown that autoreactive CD4+ cells specific for peripheral nerve P2 protein have a powerful effect on blood-nerve barrier permeability. In this study we injected CD4+ T cells reactive to a nonneural antigen (ovalbumin) systemically and achieved their accumulation in the tibial nerve of Lewis rats by previous intraneural injection of ovalbumin. Selected rats were given systemic demyelinating antibody (antigalactocerebroside) to provide an indicator of changes in the permeability of the blood-nerve barrier, and the animals were monitored by sequential neurophysiological studies and histology. Circulating ovalbumin-specific T cells accumulated at sites of intraneural ovalbumin injection without inducing demyelination in control animals. In rats with circulating galactocerebroside antibodies, local conduction block and demyelination were seen in the region of T-cell accumulation. Electron microscopy demonstrated dissolution of some tight junctions between endothelial cells in areas of T-cell accumulation, and T cells traversing the endothelium between endothelial cells and through their cytoplasm. Endothelial cell damage was evident in these areas. This study demonstrates breakdown of the blood-nerve barrier by activated T cells, even of nonneural specificity, allowing the development of focal conduction block and demyelination in the presence of circulating antimyelin antibodies.

Design and synthesis of 1-heteroaryl-3-(1-benzyl-4-piperidinyl)propan-1-one derivatives as potent, selective acetylcholinesterase inhibitors

Herein is described the synthesis and structure--activity relationship of a novel series of aromatic and heteroaromatic 3-(1-benzyl-4-piperidinyl)propan-1-one derivatives that display potent and selective inhibition of the enzyme acetylcholinesterase (AChE). 1-(2-Methyl-6-benzothiazolyl)-3-(N-benzyl-4-piperidinyl)propan-1-one hydrochloride, 6d, is one of the most active compounds within this series exhibiting an IC50 for the inhibition of the AChE enzyme equal to 6.8 nM. Compound 6d has shown a dose-dependent elevation of total acetylcholine (ACh) levels in the mouse forebrain with an oral ED50 = 9.8 mg/kg. In addition, in vivo microdialysis experiments in the rat demonstrate that 6d increases extracellular ACh (100% over basal) 1-3 h postdose with an oral ED50 = 4.8 mg/kg.

Switch transcripts in immunoglobulin class switching

B cells can exchange gene segments for the constant region of the immunoglobulin heavy chain, altering the class and effector function of the antibodies that they produce. Class switching is directed to distinct classes by cytokines, which induce transcription of the targeted DNA sequences. These transcripts are processed, resulting in spliced "switch" transcripts. Switch recombination can be directed to immunoglobulin G1 (IgG) by the heterologous human metallothionein IIA promoter in mutant mice. Induction of the structurally conserved, spliced switch transcripts is sufficient to target switch recombination to IgG1, whereas transcription alone is not.

The effects of thiopentone, etomidate, ketamine and midazolam on several bactericidal functions of polymorphonuclear leucocytes in vitro

Polymorphonuclear leucocytes (PMNL) are an essential component of the defence system against invading bacteria. There is evidence that some anaesthetics are able to suppress PMNL functions, promoting, perhaps, perioperative infection. We studied the effects of thiopentone, etomidate, ketamine, and midazolam on the generation of bactericidal agents (superoxide anion, hydrogen peroxide, and myeloperoxidase) by PMNL in vitro. Thiopentone inhibited superoxide anion (P < or = 0.01) as well as hydrogen peroxide production (P < or = 0.001). However, there was no statistically significant effect on myeloperoxidase release. Neither etomidate nor ketamine influenced the PMNL functions tested to any extent. Midazolam suppressed superoxide anion generation (P < or = 0.01) but only if a concentration far beyond clinical relevance was used.

In vivo stimulation of I kappa B phosphorylation is not sufficient to activate NF-kappa B

NF-kappa B is a major inducible transcription factor in many immune and inflammatory reactions. Its activation involves the dissociation of the inhibitory subunit I kappa B from cytoplasmic NF-kappa B/Rel complexes, following which the Rel proteins are translocated to the nucleus, where they bind to DNA and activate transcription. Phosphorylation of I kappa B in cell-free experiments results in its inactivation and release from the Rel complex, but in vivo NF-kappa B activation is associated with I kappa B degradation. In vivo phosphorylation of I kappa B alpha was demonstrated in several recent studies, but its role is unknown. Our study shows that the T-cell activation results in rapid phosphorylation of I kappa B alpha and that this event is a physiological one, dependent on appropriate lymphocyte costimulation. Inducible I kappa B alpha phosphorylation was abolished by several distinct NF-kappa B blocking reagents, suggesting that it plays an essential role in the activation process. However, the in vivo induction of I kappa B alpha phosphorylation did not cause the inhibitory subunit to dissociate from the Rel complex. We identified several protease inhibitors which allow phosphorylation of I kappa B alpha but prevent its degradation upon cell stimulation, presumably through inhibition of the cytoplasmic proteasome. In the presence of these inhibitors, phosphorylated I kappa B alpha remained bound to the Rel complex in the cytoplasm for an extended period of time, whereas NF-kappa B activation was abolished. It appears that activation of NF-kappa B requires degradation of I kappa B alpha while it is a part of the Rel cytoplasmic complex, with inducible phosphorylation of the inhibitory subunit influencing the rate of degradation.

Inhibition of brain macrophage/microglial respiratory chain enzyme activity in experimental autoimmune encephalomyelitis of the Lewis rat

We measured the activities of five respiratory chain enzymes in brain macrophages/microglial cells from Lewis rats with experimental autoimmune encephalomyelitis (EAE) and found a significant reduction of the activity of nicotinamide adenine dinucleotide-dehydrogenase (NADH-DH), succinate cytochrome c reductase (SCCR) and succinate dehydrogenase (SDH) when compared with age-matched healthy control animals. The inhibition of NADH-DH (complex I) was specific for EAE, while we also found a reduction of SCCR and SDH activities (complex II) in newborn rats and adjuvant-immunised rats. Activities of NADH cytochrome c reductase (NCCR) and cytochrome c oxidase (COX) were not significantly changed. These observations demonstrate an impairment of brain macrophage/microglial respiratory chain function in central nervous system inflammation.

A mathematical model explaining the molecular weights and distribution of very long chain dicarboxylic acids formed during the adaptive response of Sarcina ventriculi

A simple mathematical model is presented to explain a recent new discovery of an unusual membrane adaptive response in Sarcina ventriculi. In this response, this organism synthesizes very long chain alpha, omega-dicarboxylic acids ranging from 28 to 36 carbon atoms in length. The distribution of chain lengths of the new fatty acid species is not consistent with de novo synthesis but suggests elaboration from the existing regular-chain fatty acids by a coupling process. Here, we demonstrate, using a mathematical model, that if the molecular weights and relative abundances of regular chain fatty acids are known, the molecular weights and relative abundances of the new, very long chain dicarboxylic fatty acid species can be predicted using a model based on the random, pairwise combination of regular chain species. This combination takes place across the bilayer leaflet to form transmembrane fatty acids. It is proposed that this coupling phenomenon is regulated by the motional dynamics of the membrane.

Immunolocalization of vgr (BMP-6, DVR-6), a TGF-beta related cytokine, to Schwann cells of the rat peripheral nervous system: expression patterns are not modulated by autoimmune disease

The transforming growth factors type beta (TGF-beta) have been implicated in regulation of peripheral nervous system inflammation and regeneration. Here we demonstrate expression of a TGF-beta-related bone morphogenetic protein, the vgr (BMP-6, DVR-6) in Schwann cells of the rat peripheral nervous system. The expression of vgr in the peripheral nervous system suggests that this factor and probably other TGF-beta-related bone morphogenetic proteins might participate in Schwann cell function during aspects of peripheral nervous system physiology and pathology. However, we did not observe changes in expression patterns in response to autoimmune inflammation (experimental autoimmune neuritis) of the peripheral nervous system.

Therapeutic effect of transforming growth factor-beta 2 on actively induced EAN but not adoptive transfer EAN

A possible effect of transforming growth factor type-beta 2 (TGF-beta 2) on autoimmune inflammation of the peripheral nervous system (PNS) was evaluated in experimental autoimmune neuritis (EAN) in Lewis rats, a disease model of the human Guillain-Barré syndrome. First, EAN was actively induced by immunization with a neuritogenic peptide corresponding to amino acids 53-78 of the bovine P2 protein. Intraperitoneal (i.p.) administration of 5 micrograms TGF-beta 2 per day after onset of clinical disease shortened the duration and ameliorated the severity of EAN compared to sham-injected control animals. Inflammatory infiltration and demyelination was significantly reduced in sciatic nerves of TGF-beta-treated animals, although expression of major histocompatibility complex (MHC) class II antigens was not down-regulated. Second, EAN was induced by adoptive transfer (AT) of activated P2-specific T-line cells (AT-EAN). Daily injections of 5 micrograms TGF-beta 2 i.p., beginning on the day of first clinical signs, failed to modify the clinical course of AT-EAN, although the antigen-induced activation of the neuritogenic T-line cells used for induction of disease was found to be partially sensitive to the inhibitory effect of TGF-beta in vitro. The experiments indicate that TGF-beta 2 holds promise as a therapeutic agent to combat autoimmunity in the PNS. They also suggest that the therapeutic efficacy of TGF-beta on rapidly developing disease such as AT-EAN is limited, as with other non-specific immunosuppressive drugs.

Impact of 15-deoxyspergualin on effector cells in experimental autoimmune diseases of the nervous system in the Lewis rat

The influence of the immunosuppressive antibiotic agent 15-deoxyspergualin (DSG) on macrophages and autoreactive T helper lymphocytes from Lewis rats was analysed in vitro and in vivo. DSG did not inhibit antigen- or mitogen-induced proliferation of encephalitogenic or neuritogenic T helper cell lines in vitro. However, the presence of DSG during in vitro activation of the T cells strongly suppressed or completely abrogated their capacity to induce encephalitis (EAE) or neuritis (EAN) after adoptive transfer to naive rats, although expression of activation markers or adhesion molecules on the T line blasts was not down-regulated by DSG. Like activation-induced T cell proliferation, IL-2-dependent growth of CD4+ T line cells was not affected by DSG. Preincubation of CD4+ T line cells in DSG during IL-2-driven proliferation for 48 h, however, inhibited the subsequent antigen- but not mitogen-induced activation of these T cells, although neither density of T cell receptors nor other surface molecules involved in antigen recognition were lowered on the cells exposed to DSG. Similar to its effect in vitro, in vivo administration of DSG for 10 days even at a concentration with cumulative toxicity did not suppress in vitro proliferation of spleen cells induced by mitogen or a mitogenic combination of anti-CD2 antibodies. Furthermore, spleen cell and peripheral blood lymphocyte (PBL) surface antigens, particularly MHC molecules, were not altered by long-term treatment with DSG for 30 days. While there was a slight reduction in the number of polymorphonuclear cells in both populations, the proportion of the different leucocyte subpopulations remained unchanged. In contrast to the strong functional impact of DSG on autoreactive T helper cells, the drug did not inhibit the oxidative burst of macrophages or their MHC antigen expression. This study demonstrates a clear inhibitory effect of DSG on CD4+ T lymphocytes, but not macrophages. It provides an explanation for recent observations of a strong immunosuppressive in vivo effect of DSG on transplantation rejection and experimental autoimmune diseases, despite a normal mitogen response of T cells exposed to DSG in vivo and in vitro.

Crystallization and X-ray crystallographic analysis of recombinant chicken poly(ADP-ribose) polymerase catalytic domain produced in Sf9 insect cells

Poly (ADP-ribose) polymerase (PARP) participates in the immediate response in mammalian cells exposed to DNA-damaging agents. Recombinant baculovirus harboring the cDNA of the chicken PARP catalytic domain (40 kDa) have been used to infect Spodoptera frugiperda (Sf9) insect cells. The recombinant polypeptide (30 mg per 1 x 10(9) cells) was purified to homogeneity by 3-aminobenzamide affinity chromatography. The enzymatic properties of the recombinant domain were similar to those of the native fragment. Crystals of the purified recombinant catalytic domain were grown by vapor diffusion. The crystals belong to space group P2(1)2(1)2(1) with unit cell dimensions of a = 59.2 A, b = 65.0 A, c = 96.9 A. They are suitable for X-ray analysis and diffract to 2.0 A.

Structures and stereochemistry of the very long alpha, omega-bifunctional alkyl species in the membrane of Sarcina ventriculi indicate that they are formed by tail-to-tail coupling of normal fatty acids

In a previous study, we demonstrated that Sarcina ventriculi is capable of adjusting to alterations in environmental conditions (such as increase in temperature, lowering of pH, or addition of exogenous organic solvents) by the synthesis of a family of alpha, omega-dicarboxylic acids ranging from 28 to 36 carbons long (Jung, S., et al. 1993. J. Biol. Chem. 268: 2828-2835). The chain lengths and relative abundance of the very long dicarboxylic acids found in S. ventriculi suggest that they may be formed after the perturbation by the (enzymatic) tail-to-tail combinations of existing regular monofunctional fatty acids and not completely de novo by direct 2-carbon addition of acetyl coenzyme A (CoA). If this were true, knowing the structures of the regular fatty acids, we can predict those of the very long chain bifunctional acids. In this work we present definitive chemical results that strongly support this mechanism. This was done by analyzing the structures and stereochemistry of the very long bifunctional species in the light of those of the regular monofunctional species. The exact structures of membrane fatty acid methyl ester derivatives components were determined by various spectroscopic and chemical methods including gas chromatographic (GC) analysis, gas chromatography-mass spectrometry (GC-MS), 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, polarimetry, and reductive ozonolysis. This yielded precise structural and stereochemical information on the position of substitution of the acyl chain by methyl groups, position and configuration of double bonds, and optical activity. These results, coupled with the absence of intermediate length acyl species, indicated that the very long alkyl species (without exception) can be formed by tail-to-tail joining of existing fatty acids. The ideas of a dynamically regulated catalytic system is proposed.

Stent-induced intimal hyperplasia: are there fundamental differences between flexible and rigid stent designs?

PURPOSE

To evaluate possible differences in neointimal development resulting from overdilation of rigid versus flexible vascular stents.

MATERIALS AND METHODS

Twelve vascular sheaths were placed bilaterally through femoral arteries in six swine. After angiographic measurement, 12 stents (six flexible and six rigid) were balloon expanded to 8-mm diameters in 12 6-mm iliac arteries (approximately 30% overdilation). All stents were similar in surface area, gauge, and type of wire (tantalum). The primary difference was longitudinal flexibility (low hoop strength) versus rigidity (high hoop strength). Stents were studied with angiography and intravascular ultrasound 5 weeks after implantation. The animals were killed, and the stented segments were removed and examined histologically.

RESULTS

Rigid stents maintained larger diameters than flexible stents: mean, 6.52 mm versus 5.82 mm (mean difference, 0.70; standard deviation [SD], 0.47; confidence interval [CI], +/- 0.49; P < .05). In addition, rigid stents developed a thicker, eccentric neointimal reaction relative to flexible stents: mean 1.08 mm versus 0.74 mm (mean difference, 0.338; SD, 0.315; CI, +/- 0.331; P < .05).

CONCLUSION

Rigid stents maintain larger diameters over the long term relative to flexible stents when overdilated in normal swine arteries. However, a thicker neointima develops within the lumen of rigid stents at follow-up (greater late loss).

A new family of very long chain alpha,omega-dicarboxylic acids is a major structural fatty acyl component of the membrane lipids of Thermoanaerobacter ethanolicus 39E

A new family of alpha,omega-dicarboxylic, very long chain fatty acids was isolated and characterized from the lipids of thermophilic anaerobic eubacterium, Thermoanaerobacter ethanolicus 39E. After the isolation of the membrane, the fatty acyl components were converted to methyl esters by acid-catalyzed methanolysis. The esterified fatty acyl components were purified by a variety of chromatographic techniques and analyzed by gas chromatography (GC) and GC-mass spectrometry (MS). One of the isolated, esterified alpha,omega-dicarboxylic, very long chain fatty acids was characterized by mass spectrometry, 1H and 13C NMR spectroscopy and Fourier transform infrared spectroscopy. NMR experiments used included double quantum filtered correlated spectroscopy (DQF-COSY) to establish spin connectivities and polarization transfer (DEPT) to measure the multiplicity of carbon signals split by protons. Based on these results, the structures of the other components could be deduced from their mass spectra. The new family of very long chain fatty acid methyl esters are alpha,omega-13,16-dimethylheptacosanedioate dimethyl ester (C29), alpha,omega-13,16-dimethyloctacosanedioate dimethyl ester (C30), alpha,omega-13,16-dimethylnonacosanedioate dimethyl ester (C31), and alpha,omega-13,16-dimethyltriacotanedioate dimethyl ester (C32). This family of fatty acids make up about 40% of fatty acyl components of the membrane of Thermoanaerobacter ethanolicus 39E. Almost all (> 90%) of the very long chain, alpha,omega-dicarboxylic fatty acid was alpha,omega-13,16-dimethyloctacosanedioic acid. A careful analysis of the structures of the alpha,omega-dicarboxylic acid strongly implies that the synthetic mechanism for formation is by tail-to-tail (omega)coupling of regular iso-branched fatty acids across opposite sides of the membrane.

Frequency of immunoglobulin E class switching is autonomously determined and independent of prior switching to other classes

Both, in humans and in mice, a major fraction of immunoglobulin E (IgE)-expressing B lymphocytes develops by sequential Ig class switching from IgM via IgG to IgE. This sequential class switch might have functional implications for the frequency and repertoire of IgE+ cells. Here we show that in mutant mice, in which sequential switching to IgE via IgG1 is blocked, the frequency of cells switching to IgE is not affected. Thus, sequential class switching to IgE merely reflects the simultaneous accessibility of two acceptor switch regions for switch recombination, induced by one cytokine, but with markedly distinct efficiency. Analysis of switch recombination on both IgH alleles of switched cells shows that the low frequency of switching to IgE is an inherent feature of the S epsilon switch region and its control elements.

Inhibition of experimental autoimmune neuritis by an antibody to the lymphocyte function-associated antigen-1

BACKGROUND

Experimental autoimmune neuritis (EAN) is an animal model of Guillain-Barré syndrome. The mechanisms underlying cellular trafficking and homing of autoreactive immune cells to the peripheral nervous system during EAN and Guillain-Barré syndrome are unknown. We investigated the role of the adhesion molecule lymphocyte function-associated antigen-1 in the pathogenesis of EAN.

EXPERIMENTAL DESIGN

EAN was induced in Lewis rats either by immunization with bovine spinal root myelin or by adoptive transfer of P2-specific T cells. Animals were treated intraperitoneally with a monoclonal antibody to lymphocyte function-associated antigen-1 (WT-1) or phosphate-buffered saline and scored for clinical signs. Histology was performed on sciatic nerve and cauda equina and assessed for infiltration and demyelination. Severity of EAN and the corresponding histologic alterations were compared in the different treatment groups. The in vitro effect of WT-1 on T cell proliferation was evaluated.

RESULTS

Treatment with WT-1 prevented or efficiently suppressed myelin-induced EAN. In contrast, sham treatment of animals failed to alter the clinical course of EAN. Histologic examination of the peripheral nervous system showed a marked reduction of inflammatory infiltration and perivascular demyelination in animals treated with WT-1. Adoptive transfer EAN was not affected by the administration of WT-1. The differential action in the two models suggests that WT-1 appears to act primarily on the induction phase of the immune response but has no significant impact on the effector phase. In vitro studies with WT-1 revealed that the antibody inhibits the concanavalin A-dependent proliferation of neuritogenic P2-specific T cells.

CONCLUSIONS

Our data indicate that lymphocyte function-associated antigen-1 is critically involved in the pathogenesis of EAN. Further analysis of this model may provide insight into the process of immune cell recruitment from the circulation into the peripheral nervous system in immune-mediated neuropathies.

The Saccharomyces cerevisiae gene PPH3 encodes a protein phosphatase with properties different from PPX, PP1 and PP2A

A clone encoding the catalytic subunit of a protein phosphatase from Saccharomyces cerevisiae was isolated. Except for replacement of IIe-245 by Met the structure of the phosphatase was identical to that encoded by PPH3 (Ronne, H., Carlberg, M., Hu, G. Z. and Nehlin, J. O. (1991). Mol. Cell. Biochem. 11, 4876-4884) and exhibited 63% sequence identity to PPX cloned from a rabbit liver cDNA library (Brewis, N.D., Street, A.J., Prescott, A.R. and Cohen, P.T.W. (1993). EMBO J. 12, 987-996). Expression of active enzyme was achieved in Escherichia coli mutants which were generated by a genetic selection based on functional complementation of bacterial phosphoserine phosphatase. Though some of the properties of PPH3 resembled those of protein phosphatase 2A and PPX, others were different. PPH3 exhibited lower sensitivity against inhibition by okadaic acid, showed different substrate specificity and required a divalent cation (Mn2+ was preferred before Mg2+ and Ca2+) for activity when assayed with phospho-histone as a substrate. However, 25% of maximum activity was observed in the absence of divalent cations when the peptide LRRAS(P)LG was used as substrate. The PPH3-protein was also identified by chromatography of extracts from S. cerevisiae on DEAE-cellulose. Protein immunoreactive with an antiserum raised against the non-conserved N-terminal 53 amino acids of PPH3 was coeluted with a single peak of LRRAS(P)LG dephosphorylating activity.

Selective elimination of macrophages by dichlormethylene diphosphonate-containing liposomes suppresses experimental autoimmune neuritis

The injection of liposome-encapsulated dichlormethylene diphosphonate (Cl2MDP) constitutes an effective method to selectively eliminate phagocytic cells from spleen, liver and the circulation. We evaluated the effect of Cl2MDP-liposomes on the course of actively induced and adoptively transferred experimental autoimmune neuritis (EAN), both animal models of the human Guillain-Barré syndrome. Injection of Cl2MDP-liposomes 11 and 13 days postimmunization (p.i.) of Lewis rats with bovine peripheral nerve myelin efficiently prevented clinical signs of EAN up to day 15 p.i., when all control animals were affected. Thereafter, EAN gradually also developed in Cl2MDP-liposome-treated rats, but until day 19 disease was significantly milder than in control rats injected with buffer-filled liposomes. Adoptive transfer EAN (AT-EAN) induced by injection of activated P2-specific T cells could be suppressed even more markedly by application of Cl2MDP-liposomes 1, 3, and 6 days after cell transfer. Efficient suppression of AT-EAN by Cl2MDP-liposomes rules out the possibility that EAN is prevented due to interference with the induction phase of this experimental disease and confirms that macrophages are important effector cells during EAN. Selective suppression of phagocytic cell function by drug-containing liposomes may hold promise as a novel treatment of demyelinating autoimmune diseases of the nervous system.

Suppression of experimental allergic neuritis by an antibody to the intracellular adhesion molecule ICAM-1

Experimental allergic (autoimmune) neuritis (EAN) was induced in Lewis rats either by inoculation with bovine spinal root myelin or injection of neuritogenic P2-specific T cells. Injection of a purified monoclonal antibody (1A-29) to the intercellular adhesion molecule-1 (ICAM-1) prevented or transiently suppressed myelin-induced EAN depending on the timing of antibody application. Administration of 1A-29 suppressed moderate adoptive transfer EAN (AT-EAN) but not severe AT-EAN. In contrast, treatment with phosphate buffered saline or an unrelated IgG1 had no effect on the course of the disease. Histological sections of the peripheral nervous system (PNS) showed a marked reduction of inflammatory infiltrates and perivascular demyelination in rats injected with 1A-29. The effect of 1A-29 on the concanavalin A (Con A)- and P2-dependent proliferation of neuritogenic P2-specific T cells was studied in vitro. Our data suggest that antibodies to ICAM-1 act on the induction and effector phase of the immune response by inhibiting both early interactions between immunocompetent cells after exposure to foreign antigen and transendothelial migration of primed T cells into the peripheral nerve. Treatment with antibodies to leucocyte adhesion molecules could be a useful therapeutic approach to autoimmune disease of the PNS.

Leukocytic antimicrobial peptides kill autoimmune T cells

Small antimicrobial peptides are abundantly produced by leukocytes. These peptides are active against a broad range of pathogens, notably bacteria, fungi and enveloped viruses, but hardly anything is known about their physiological and pathophysiological relevance. We observed that indolicidin, and to a lesser extent bactenecin, are strongly cytotoxic to rat and human T lymphocytes, while a variety of other cell lines are not affected by these endogenous antibiotics. The defensins HNP-1, HNP-2 and HNP-3, the structurally related but not bactericidal corticostatin, or cecropin P1 did not affect T lymphocyte viability or proliferation. Thus, indolicidin and bactenecin might function as local regulators inhibiting clonal expansion of T lymphocytes during ongoing immune responses. As immunosuppressive agents in the treatment of autoimmune disease, these peptides appear to be of limited potential, as systemic activity of such peptides is low, and we did not observe significant immunosuppressive effects in experimental autoimmune neuritis or encephalomyelitis.

The influence of intravenous anaesthetics on polymorphonuclear leukocyte function

Polymorphonuclear leukocytes (PMNL) play a vital role in the defence against invading bacteria. It is known that some anaesthetics inhibit PMNL function and, thus, possibly enhance perioperative infection. We investigated the effect of methohexitone, flunitrazepam, and droperidol on three bactericidal PMNL functions, i.e., superoxide anion production, hydrogen peroxide generation, and activity of released myeloperoxidase, in vitro. Approved photometrical assays were used. Superoxide anion was measured by the reduction of cytochrome C, hydrogen peroxide by the horse radish peroxidase catalysed oxidation of phenol red, and myeloperoxidase by the turnover of 2,2'-azino-di(3-ethylbenzthiazoline) sulfonic acid. Methohexitone (P < or = 0.001) and flunitrazepam (P < or = 0.01) inhibited superoxide anion production, and methohexitone (P < or = 0.01) reduced hydrogen peroxide generation but only at concentrations beyond clinical relevance. Droperidol did not cause any alteration of the PMNL functions tested. Consequently, it seems unlikely that the usual doses of methohexitone, flunitrazepam, or droperidol promote bacterial infections in vivo by impairing the activity of myeloperoxidase or by inhibiting the generation of superoxide anion or hydrogen peroxide.