Eosinophil levels in the acute phase of experimental chagas' disease

Eosinophil dynamics, in bone marrow, blood and peritoneal exudate, of resistant C57B1/6 (C57) and susceptible A/Snell (A/Sn) mice was comparatively studied during the acute phase of infection by Trypanosoma cruzi Y strain. A decline was observed in bone marrow eosinophil levels in A/Sn, but not in C57 mice, soon after infection, those of the former remaining significantly below those of the latter up to the 4th day of infection. Bone marrow eosinophil levels of C57 mice declined subsequently to levels comparable to those of A/Sn mice, the number of these cells in this compartment remaining 50% those of non infected controls, in both strains, up to the end of the experiment on the 14th day of infection. The fluctuations in eosinophil levels in blood and peritoneal space were similar in both mice strains studied. Concomitantly with depletion of eosinophils in the marrow, depletion in blood and a marked rise of these cells in the peritoneal space, initial site of infection, occurred in both strains. The difference in eosinophil bone marrow levels, between C57 and A/Sn mice, observed in the first four days of infection, suggests a higher eosinopoiesis capacity of the former in this period, which might contribute to their higher resistance to T. cruzi infection

Impaired Innate Immunity in Tlr4−/− Mice but Preserved CD8+ T Cell Responses against Trypanosoma cruzi in Tlr4-, Tlr2-, Tlr9- or Myd88-Deficient Mice

The murine model of T. cruzi infection has provided compelling evidence that development of host resistance against intracellular protozoans critically depends on the activation of members of the Toll-like receptor (TLR) family via the MyD88 adaptor molecule. However, the possibility that TLR/MyD88 signaling pathways also control the induction of immunoprotective CD8+ T cell-mediated effector functions has not been investigated to date. We addressed this question by measuring the frequencies of IFN-γ secreting CD8+ T cells specific for H-2Kb-restricted immunodominant peptides as well as the in vivo Ag-specific cytotoxic response in infected animals that are deficient either in TLR2, TLR4, TLR9 or MyD88 signaling pathways. Strikingly, we found that T. cruzi-infected Tlr2−/−, Tlr4−/−, Tlr9−/− or Myd88−/− mice generated both specific cytotoxic responses and IFN-γ secreting CD8+ T cells at levels comparable to WT mice, although the frequency of IFN-γ+CD4+ cells was diminished in infected Myd88−/− mice. We also analyzed the efficiency of TLR4-driven immune responses against T. cruzi using TLR4-deficient mice on the C57BL genetic background (B6 and B10). Our studies demonstrated that TLR4 signaling is required for optimal production of IFN-γ, TNF-α and nitric oxide (NO) in the spleen of infected animals and, as a consequence, Tlr4−/− mice display higher parasitemia levels. Collectively, our results indicate that TLR4, as well as previously shown for TLR2, TLR9 and MyD88, contributes to the innate immune response and, consequently, resistance in the acute phase of infection, although each of these pathways is not individually essential for the generation of class I-restricted responses against T. cruzi

Specific Humoral Immunity versus Polyclonal B Cell Activation in Trypanosoma cruzi Infection of Susceptible and Resistant Mice

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, affects 10–12 million people in Latin America. Patent parasitemia develops during acute disease. During this phase, polyclonal B cell activation has been reported to generate high levels of serum antibody with low parasite specificity, and delayed protective humoral immunity, which is necessary to prevent the host from succumbing to infection. In this manuscript, data show that relatively resistant mice have improved parasite-specific humoral immunity and decreased polyclonal B cell activation compared to susceptible mice. Parasite-specific humoral immunity was associated with differential expansion of B cell subsets and T cells in the spleen, as well as with increased Th1 and decreased Th2 cytokine production. These data suggest that host susceptibility/genetic biases impact the development of humoral responses to infection. Th2 cytokines are generally associated with improved antibody responses. In the context of T. cruzi infection of susceptible mice, Th2 cytokines were associated with increased total antibody production concomitant with delayed pathogen-specific humoral immunity. This study highlights the need to consider the effect of host biases when investigating humoral immunity to any pathogen that has reported polyclonal B cell activation during infection

Mono- and bideuterated l-phenylalanines

From the bromination products of l-phenylalanine we recently isolated and identified the following optically pure substances: 2-bromophenylalanine, 4-bromophenylalanine, a small amount of 2,3-dibromophenylalanine, 2,5-dibromophenylalanine, and 3,4-dibromophenylalanine (1). Deuteration of all these compounds except one was studied in order to obtain l-phenylalanines which were labeled in the aromatic ring. Deuteration was carried out on Pd-catalysts with either D2 gas or NaBD4

Permethylierung von Inosit und anderen Kohlenhydraten mit Dimethylsulfat

Bei Methylierungen in Dimethylformamid ist es vielfach von Vorteil, Dimethylsulfat an stelle von Methyljodid zu verwenden. Substanzen, die in Dimethylformamid zu wenig löslich sind, methyliert man in Dimethylsulfoxyd bzw. in Dimethylformamid/Dimethylsulfoxyd-Gemischen. Auf diese Art wurde Mesoinosit-hexamethyläther kristallisiert (Schmp. 18°) erhalten

Monoketale von 1.2-Diketonen. Ein Beitrag zur Theorie der Benzilsäure-Umlagerung

Benzil und Phenanthrenchinon werden durch Methyljodid in Dimethylformamid unter Zusatz von Silberoxyd bzw. Bariumoxyd in die Monoketale [BOND]CO[BOND]C(OCH3)2[BOND]verwandelt. Monoketone wie Benzophenon und Fluorenon bleiben unter denselben Bedingungen unverändert. Aus 1.2.3-Triketonen wie Ninhydrin erhält man die Monoketale. Indigo, der als nicht methylierbar galt, liefert glatt N.N′-Dimethyl-indigo. — Das aus Benzil durch Addition von OH⊖ an eine Ketogruppe entstehende Anion VI wird unter den Bedingungen der Methylierung als Dimethylketal I abgefangen

Über Peptidsynthesen, XLVI. Synthese von Peptiden des γ-Hydroxy-leucins

Dia Synthese von L-Tryptophyl-L-γ-hydroxyleucyl-L-alanyl-D-threonin-methylester (6), einer Teilsequenz des Knollenblätterpilzgiftes Phalloin, welche wegen der anchimer erleichterten Peptid-Spaltung durch die γ-Hydroxyl-Gruppe mit besonderen Schwierigkeiten verbunden ist, gelingt wie folgt: Aus Z-DL-γHydroxy-leucinlation wird mit L-Alanin-Na in der Imidazol-Schmelze Z-DL-γ-Hydroxyleucyl-L-alanin (4a) erhalten, das wegen seiner raschen Autolyse sofort mit Diazomethan zum beständigeren 4b verestert werden muß. Nach katalytischer hydrogenolytischer Z-Abspaltung wird der Ester 4c mit Z-L-Tryptophan zum Gemisch diastereomerer Tripeptidester 5b gekuppelt, das nach der Hydrolyse über das gemischte Alkylkohlensäureanhydrid mit D-Threonin-methylester verbinden wird. Aus dem Reaktions-gemisch erhält man durch fraktionierte Kristallisation außer dem L.D.L.D-Diastereomeren das L.D.L.D.-Tetrapeptid-Derivat 6