[Therapeutic effect of encapsulated into the nanocontainers MBP immunodominant peptides on EAE development in DA rats].

Multiple Sclerosis (MS) is a serve autoimmune neurodegenerative disease. Development of innovative approaches of MS treatment is of a high priority in the modern immunology and pharmacy. In the present study we showed high therapeutic efficiency of immunodominant peptides of myelin basic protein (MBP) incorporated into the monolayer mannosylated liposomes on the development of experimental autoimmune encephalomyelitis (EAE) in DA rats. MBP is a component ofoligodendrocytes' membrane, which form axonal sheath, and is one of the major autoantigens in MS. We analyzed binding pattern ofanti-MBP autoantibodies from MS patients using previously designed MBP epitope library. Utilizing the same approach we investigated pool of anti-MBP antibodies from SJL/J and C57/BL6 mice and DA rats with induced EAE. The most relevant rodent model to MS was EAE in DA rats according to the autoantibodies' binding pattern. We selected three immunodominant MBP fragments encapsulated in monolayer mannosylated liposomes for the following treatment of verified DA rodent model. MBP fragment 46-62 was the most effective in reducing of the first EAE attack, whereas MBP 124-139 and 147-160 inhibited development of pathology during remission stage. Simultaneous administration of these peptides in liposomes significantly decreased level of anti-MBP antibodies. Synergetic therapeutic effect of MBP fragments reduced integral disease score by inhibiting first EAE wave and subsequent remission, thus, our findings disclosure novel approaches for efficient treatment of Multiple Sclerosis.

Antigen receptor signaling competence and the determination of B cell fate in B-lymphopoiesis.

Recent studies suggest that developmental check-points in B-lymphopoiesis are set in order to test the B cell receptor signaling competence. In these check-points ligand-independent and ligand-dependent receptor signals confer B-lymphopoiesis with positive and negative selection events. As a consequence, B-lymphocytes are forced to make crucial fate decisions to determine developmental progression, survival or apoptosis. In here we review recent progress in unraveling molecular and cellular mechanisms for the role of B cell receptor signaling competence in determination of the B cell fate.

Selection events in directing B cell development.

Homeostasis in the B cell compartment (as well as in T cells) is controlled by tightly regulated selection events. Throughout their life span, B cells are subjected to selection signals determining not only developmental progression, but also maturation and survival. It is now clear that most of these signals require the expression of B cell antigen receptor (or preB receptor) with functional signaling capacity. The administration of numerous mutations into the mouse germline enabled us to identify several checkpoints along the B cell developmental pathway, and provided us with powerful experimental tools to probe for selection events regulating developmental progression. In here, we will discuss recent studies in this field.

Sulfur polymer solidification/stabilization of elemental mercury waste.

Elemental mercury, contaminated with radionuclides, presents a waste disposal problem throughout the Department of Energy complex. In this paper we describe a new process to immobilize elemental mercury wastes, including those contaminated with radionuclides, in a form that is non-dispersible, will meet EPA leaching criteria, and has low mercury vapor pressure. In this stabilization and solidification process, elemental mercury is combined with an excess of powdered sulfur polymer cement (SPC) and sulfide additives in a mixing vessel and heated to approximately 40 degrees C for several hours, until all of the mercury is converted into mercuric sulfide (HgS). Additional SPC is then added and the temperature of the mixture raised to 135 degrees C, resulting in a molten liquid which is poured into a mold where it cools and solidifies. The final treated waste was characterized by powder X-ray diffraction and found to be a mixture of the hexagonal and orthorhombic forms of mercuric sulfide. The Toxicity Characteristic Leaching Procedure was used to assess mercury releases, which for the optimized process averaged 25.8 microg/l, with some samples being well below the new EPA Universal Treatment Standard of 25 microg/l. Longer term leach tests were also conducted, indicating that the leaching process was dominated by diffusion. Values for the effective diffusion coefficient averaged 7.6x10(-18) cm2/s. Concentrations of mercury vapor from treated waste in equilibrium static headspace tests averaged 0.6 mg/m3.

Molecular structures and magnetic resonance spectroscopic investigations of highly distorted six-coordinate low-spin iron(III) porphyrinate complexes.

Three bis-axially ligated complexes of iron(III) octaethyltetraphenylporphyrin, (OETPP)Fe(III), have been prepared, which are low-spin complexes, each with two axial nitrogen-donor ligands (N-methylimidazole (N-MeIm), 4-(dimethylamino)pyridine (4-NMe(2)Py), and 2-methylimidazole (2-MeImH)). The crystal and molecular structure of the bis-(2-MeImH) complex shows the macrocycle to be in a saddled conformation, with the ligands in perpendicular planes aligned at 14 degrees to the porphyrin nitrogens so as to relieve the steric interaction between the 2-methyl groups and the porphyrin. The Fe-N(por) bond lengths are typical of nonplanar six-coordinate low-spin Fe(III) complexes, while the axial Fe-N(ax) bond lengths are substantially longer than those of [(TPP)Fe(2-MeImH)(2)](+) (2.09(2) A as compared to 2.015(4) and 2.010(4) A). The crystal and molecular structure of the bis-(4-NMe(2)Py) complex also shows the macrocycle to be in a mainly saddled conformation, but with a significant ruffled component. As a result, the average Fe-N(por) bonds are significantly shorter (1.951 A as compared to 1.974 A) than those of the bis-(2-MeImH) complex. One ligand is aligned at 9 degrees to two trans porphyrin nitrogens, while the other is at 79 degrees to the same porphyrin nitrogens, producing a dihedral angle of 70 degrees between the ligand planes. The EPR spectrum of this complex, like that of the bis-(2-MeImH) complex, is of the "large g(max)" type, with g(max) = 3.29 and 3.26, respectively. However, in frozen CD(2)Cl(2), [(OETPP)Fe(N-MeIm)(2)](+) exhibits both "large g(max)" and normal rhombic signals, suggesting the presence of both "perpendicular" and "parallel" ligand orientations. The 1- and 2D (1)H NMR spectra of each of these complexes, as well as the chloroiron(III) starting material, were investigated as a function of temperature. The COSY and NOESY/EXSY spectra of the chloride complex are consistent with the expected J-coupling and saddle inversion dynamics, respectively. Complete spectral assignments for the bis-(N-MeIm) and -(4-NMe(2)Py) complexes have been made using 2D (1)H NMR techniques. In each case, the number of resonances due to methylene (two) and phenyl protons (one each) is consistent with D(2)(d)() symmetry, and therefore an effective perpendicular orientation of the axial ligands on the time scale of the NMR experiments. The temperature dependences of the (1)H resonances of these complexes show significant deviations from Curie behavior, and also evidence of extensive ligand exchange and rotation. Spectral assignment of the eight methylene resonances of the bis-(2-MeImH) complex to the four ethyl groups was possible through the use of 2D (1)H NMR techniques. The complex is fluxional, even at -90 degrees C, and ROESY data suggest that the predominant process is saddle inversion accompanied by simultaneous rotation of the axial ligands. Saddle inversion becomes slow on the 2D NMR time scale as the temperature is lowered in the ligand order of N-MeIm > 4-NMe(2)Py > 2-MeImH, probably due mainly to progressive destabilization of the ground state rather than progressive stabilization of the transition state of the increasingly "hindered" bis-ligand complexes.

Unexpected autoantibody production in membrane Ig-mu-deficient/lpr mice.

In the B lymphocyte lineage, Fas-mediated cell death is important in controlling activated mature cells, but little is known about possible functions at earlier developmental stages. In this study we found that in mice lacking the IgM transmembrane tail exons (muMT mice), in which B cell development is blocked at the pro-B stage, the absence of Fas or Fas ligand allows significant B cell development and maturation, resulting in high serum Ig levels. These B cells demonstrate Ig heavy chain isotype switching and autoimmune reactivity, suggesting that lack of functional Fas allows maturation of defective and/or self-reactive B cells in muMT/lpr mice. Possible mechanisms that may allow maturation of these B cells are discussed.

Determination of the chiral isomers of CGS 26214, a synthetic thyromimetic agent, in human plasma using microbore chiral chromatography-tandem mass spectrometry.

CGS 26214 is a racemic compound having cholesterol-lowering activity in rats, dogs, and monkeys. This compound has two equipotent chiral components CGS 28934(-) and CGS 28935(+). An analytical challenge was to develop a sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the analysis of the chiral components in human plasma following clinical doses of 1 mg or less. Several issues had to be addressed in order to devise a LC/MS/MS assay for the above compounds. First, the compounds were esters and susceptible to hydrolysis under experimental conditions. Second, a lower limit of quantitation (LLOQ) of 0.4 ng/ml was needed. Third, positive electrospray ionization of CGS 26214 did not yield sufficient sensitivity needed for the studies in humans. Consequently, LC/MS/MS conditions were optimized for negative ion mode of detection. Fourth, sample preparation steps proved to be critical in order to reduce the possibility of microbore chiral-HPLC column (100 x 1.0 mm i.d.) obstruction, chromatographic deterioration, and matrix mediated electrospray ion suppression. Although the present method addressed the above challenges, its major drawback was limited sample throughput capability. Nonetheless, the method was successfully applied to generate plasma concentration-time profiles for human subjects after oral doses (0.9 mg) of the racemate as well as the optically pure isomers.

Determination of terbinafine (Lamisil) in human hair by microbore liquid chromatography/tandem mass spectrometry.

An analytical method for the determination of terbinafine (Lamisil(R)) in human hair was developed and validated. Human hair (10 mg) was hydrolyzed in 0.50 mL of 5.0 N sodium hydroxide for 1.5 h. The aqueous layer was extracted with 1.5 mL of n-hexane. The organic layer was separated and re-extracted with 0.20 mL of formic acid (12.5%)/2-propanol (85:15, v/v). The aqueous layer was separated and 0.010 mL of the aqueous extract was injected onto a reversed-phase microbore (50 x 1.0 mm i.d.) column for analysis by liquid chromatography/tandem mass spectrometry (LC/MS/MS). The instrument was equipped with an electrospray ionization (ESI) interface and operated in the positive ion mode of detection. Interday and intraday accuracy and precision were assessed from the relative recoveries of spiked samples analyzed on three different days. The method showed excellent specificity and ruggedness with a lower limit of quantitation of 10 ng/g (i.e., 10 ppb) using 10 mg of human hair.

Trace-level quantitation of iralukast in human plasma by microbore liquid chromatography/tandem mass spectrometry.

Iralukast (CGP 45715A) is a potent peptido-leukotriene antagonist that is active in various in vitro and animal models for the treatment of asthma. An analytical challenge was to develop a sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method with a lower limit of quantitation (LLOQ) of 10 pg/mL for the analysis of iralukast when administered at low doses during clinical trials. Several issues had to be addressed in order to devise a LC/MS/MS assay for the above compound. First, iralukast appeared to be light sensitive and unstable at room temperature under acidic conditions. Second, a LLOQ of 10 pg/mL was needed to support several clinical trials. Third, positive electrospray ionization of iralukast did not yield the necessary sensitivity required for studies in humans. Consequently, LC/MS/MS conditions were optimized for the negative ion mode of detection. Fourth, sample preparation steps proved to be critical to reduce the possibility of microbore HPLC column (50 mm x 1.0 mm i.d.) obstruction, chromatographic deterioration, and matrix-mediated electrospray ion suppression. While our validated method addressed the above challenges, its major drawback was limited sample throughput capability. Nonetheless, plasma concentration-time profiles for patients with moderate asthma after oral administration of 200, 500, 1000, and 5000 microgram/kg/day of iralukast were successfully obtained.

B-cell-receptor-dependent positive and negative selection in immature B cells.

This review touches on only a small part of the complex biology of B cells, but serves to illustrate the point that the antigen receptor is the most important of many cell-surface receptors affecting cell-fate decisions. Receptor expression is necessary, but not sufficient, for cell survival. It is also essential that a B cell's antigen-receptor specificity be appropriate for its environment. The need to balance reactivity with self tolerance has resulted in an intricate feedback control (affected by both the recombinase and cell survival) that regulates independent selection events at the level of the receptor and the cell.

Distinct signal thresholds for the unique antigen receptor-linked gene expression programs in mature and immature B cells.

Although it is well established that immature B lymphocytes are exquisitely sensitive to tolerance induction compared with their mature counterparts, the molecular basis for this difference is unknown. We demonstrate that signaling by B cell antigen receptors leads to distinct and mutually exclusive biologic responses in mature and immature B cells: upregulation of CD86, CD69, and MHC class II in mature cells and receptor editing in immature cells. These responses can be induced simply by elevation of intracellular free calcium levels, as occurs after receptor aggregation. Importantly, induction of immature B cell responses requires much smaller increases in intracellular free calcium than does induction of mature B cell responses. These differences in biologic response and sensitivity to intracellular free calcium likely contributes to selective elimination at the immature stage of even those B cells that express low affinity for self-antigens.

Developmental regulation of B lymphocyte immune tolerance compartmentalizes clonal selection from receptor selection.

B lymphocyte development is a highly ordered process that involves immunoglobulin gene rearrangements, antigen receptor expression, and a learning process that minimizes the development of cells with reactivity to self tissue. Two distinct mechanisms for immune tolerance have been defined that operate during early bone marrow stages of B cell development: apoptosis, which eliminates clones of cells, and receptor editing, which spares the cells but genetically reprograms their autoreactive antigen receptors through nested immunoglobulin L chain gene rearrangements. We show here that sensitivity to antigen-induced apoptosis arises relatively late in B cell development and is preceded by a functionally distinct developmental stage capable of receptor editing. This regulation compartmentalizes clonal selection from receptor selection.

Defective immune response and failure to induce oral tolerance following enterai exposure to antigen in broilers afflicted with stunting syndrome.

Infectious stunting syndrome (SS) in broilers is a multi-symptomatic disease that includes lesions in the intestinal tract. We investigated whether these lesions impeded functions of the intestinal immune system. Two functions were studied: the capacity to generate 1) immune responses to a resident pathogen .(E. coli) of the gut and to a parenterally administered antigen (ss-casein), and 2) tolerance to an orally administered antigen (ss-casein). SS was induced in day-old broilers by an inoculum prepared from SS afflicted broilers. After onset of SS, immune responses (or absence of, in the case of tolerance) were studied by specific antibody production and T lymphocyte proliferation. Immune responses were induced by subcutaneous immunization of broilers against ss-casein or following natural exposure to enteric .E. coli. Oral tolerance was induced by a single feeding of ss-casein in gelatine capsules. Both enterai anti-E. .coli and parenteral anti-ss-casein responses were significantly reduced in SS birds. SS afflicted broilers did not develop ss-casein-specific oral tolerance. These results indicate dysfunction of both the intestinal immune system and that of systemic acquired immune responses in SS.

A functional B cell receptor transgene allows efficient IL-7-independent maturation of B cell precursors.

IL-7 supports the proliferation of B cell precursors, but inhibits their maturation to mature surface IgM+ (sIgM+) B cells. This inhibition is thought to occur by direct or indirect down-regulation of recombinase genes, preventing the B cells from undergoing Ig light chain rearrangements. To directly analyze the IL-7 inhibitory effects, we studied B cell development and maturation in B cells bearing a transgenic (Tg) B cell receptor (BCR). We show here that proliferation of Tg B cell precursors is IL-7 dependent both in vivo and in vitro and is comparable to that of non-Tg B cell precursors. Tg B cell precursors grown on stroma and IL-7 expressed sIgM on >90% of the cells, and a large proportion of these cells coexpressed additional maturation markers such as IgD, CD23, CD21, and L-selectin, indicating that IL-7 does not inhibit maturation of Tg B cell precursors. The presence of the Tg inhibited V(D)J recombination in the cultured cells, as very low levels of recombination activating genes 2 (RAG-2) expression and endogenous V-Jkappa DNA rearrangements were found. Expression levels of RAG mRNAs were not significantly changed after removal of IL-7 from the in vitro Tg B cell cultures. In contrast, we found that IL-7 inhibited maturation of non-Tg B cell precursors and that removal of IL-7 resulted in a significant increase in RAG-2 expression and kappa rearrangements, thus allowing the B cells to express sIgM and to mature. These results suggest that IL-7-mediated inhibition of Ig gene rearrangement blocks maturation of B cell precursors and that the presence of Tg BCR efficiently circumvents this inhibition.

Self-antigen does not accelerate immature B cell apoptosis, but stimulates receptor editing as a consequence of developmental arrest.

In pre-B lymphocytes, productive rearrangement of Ig light chain genes allows assembly of the B cell receptor (BCR), which selectively promotes further developmental maturation through poorly defined transmembrane signaling events. Using a novel in vitro system to study immune tolerance during development, we find that BCR reactivity to auto-antigen blocks this positive selection, preventing down-regulation of light chain gene recombination and promoting secondary light chain gene rearrangements that often alter BCR specificity, a process called receptor editing. Under these experimental conditions, self-antigen induces secondary light chain gene rearrangements in at least two-thirds of autoreactive immature B cells, but fails to accelerate cell death at this stage. These data suggest that in these cells the mechanism of immune tolerance is receptor selection rather than clonal selection.

Alpha interferon suppresses the cyclin D3 and cdc25A genes, leading to a reversible G0-like arrest.

Alpha interferon is a potent growth inhibitor of Daudi Burkitt's lymphoma cells. We show here that alpha-interferon signaling interacted simultaneously with several components of the basic cell cycle machinery, causing cells to enter into a state that had many features characteristic of the G0 state. Within a few hours after alpha-interferon treatment, cyclin D3 mRNA and protein levels dropped to undetectable levels and, in parallel, the activities of cyclin A- and cyclin E-associated kinases were significantly reduced. The latter resulted from the rapid alpha-interferon-mediated elimination of cdc25A, a phosphatase that is required for antagonism of negative tyrosine phosphorylation of cdk2 in cyclin-cdk complexes. This regulation represents a novel mechanism through which an external inhibitory cytokine interacts with the cell cycle machinery. At later time points after alpha-interferon treatment, the levels of the 55-kDa slowly migrating hyperphosphorylated form of cyclin E and of cyclin A were also reduced. The antiproliferative effects were reversible, and cultures from which alpha interferon was removed reentered S phase after a lag that typically corresponded to approximately two doubling times. During this lag period, the expression of cyclin D3 and cyclin A, as well as of the cdc25A phosphatase, continued to be switched off, in spite of the removal of alpha interferon from the cell surface. In contrast, c-myc, which represents another downstream target gene that is subjected to negative regulation by alpha interferon, was relieved from suppression much earlier, concomitant with the decay in early signaling of the cytokine. The delayed pattern of cyclin reexpression provides evidence that alpha-interferon signaling imposes a G0-like state on this system.

Peripheral tolerance of Th2 lymphocytes induced by continuous feeding of ovalbumin.

We established conditions for inducing antigen-specific tolerance in Th2 lymphocytes by means of oral tolerance. Mice were continuously exposed to ovalbumin in their drinking water for a minimal period of 20 days and then immunized against antigen in either complete Freund's adjuvant or Al(OH)3. This feeding regimen tolerized both Th2 and Th1 responses as shown by diminished proliferation, cytokine secretion (IL-4, IL-2 and IFN-gamma) and specific cytokine mRNA expression (IL-4, IL-2 and IFN-gamma) in vitro, as well as by absence of specific antibody production (IgG1, IgG2a, IgG2b and IgE) in vivo. Conditions for generating Th2 lymphocyte tolerance were different from those required to generate tolerance in Th1 lymphocytes: these included extended, continuous exposure to high dosages of antigen, rather than a single or intermittent feeding regimen which was sufficient to induce tolerance in Th1 lymphocytes. These findings suggest that continuous oral exposure to a tolerogen may be a biologically relevant strategy to tolerize both Th1- and Th-dependent responses, and extend the potential clinical use of oral tolerance to ailments mediated by Th2 lymphocytes.

The effect of varying dietary concentrations of vitamin A on immune response in the turkey.

1. The effect of dietary vitamin A on antibody production and T-cell proliferative response was determined in poults from 21 to 41 d old. Poults were fed on soyabean meal-sorghum-based diets with concentrations of supplemented vitamin A from 0 to 13.2 micrograms/g retinol equivalents from hatching and were immunised with Newcastle disease virus (NDV) and turkey pox vaccines. T-cell proliferation response to concanavlin A was determined in vitro at 31 d old. Antibodies to NDV and turkey pox in serum were determined at 10 and 20 d after inoculation. 2. Poults receiving the diet with no added dietary vitamin A died by 22 d and had very low concentrations of plasma and liver vitamin A. 3. Increasing dietary concentrations of vitamin A enhanced the proliferative response until the diet contained 6.0 micrograms/g, above which the response began to decrease. The antibody titres to NDV and turkey pox increased as dietary vitamin A increased, with maximal values found 10 d after inoculation with 6.0 micrograms/g. At 20 d after inoculation low antibody titres were found with low vitamin A intake. 4. These data suggest that maximal immune responses in the poult may be achieved at dietary intakes of vitamin A at or higher than those recommended by NRC (1984, 1994).