Impaired Th2 subset development in the absence of CD4

Prior studies in CD4-deficient mice established the capacity of T helper (Th) lineage cells to mature into Th1 cells. Unexpectedly, challenge of these mice with Nippostrongylus brasiliensis, a Th2-inducing stimulus, failed to result in the development of Th2 cells. Additional studies were performed using CD4+ or CD4-CD8- (double-negative) T cell receptor (TCR) transgenic T cells reactive to LACK antigen of Leishmania major. Double-negative T cells were unable to develop into Th2 cells in vivo, and, unlike CD4+ T cells, could not be primed for interleukin-4 production in vitro. Similarly, CD4+ TCR transgenic T cells primed on antigen-presenting cells expressing mutant MHC class II molecules unable to bind CD4 did not differentiate into Th2 cells. These data suggest that interactions between the TCR, MHC II-peptide complex and CD4 may be involved in Th2 development.     

Chemical,nutritive, deoxynivalenol and zearalenone content of corn relative to the site of inoculation with different isolates of Fusarium graminearum

Kernels from two samples of 18 ears of corn were hand-shelled into three fractions (Fl, F2 and F3) relative to the site (F3) where the ears had previously been inoculated with one of four isolates of Fusarium graminearum (Schwabe). F3 and Fl were from the nearest and remotest parts of the ear, respectively, to the inoculation site. Ears of uninoculated control corn were processed in the same manner. The resulting 30 samples were analysed, after grinding (20 mesh), for deoxynivalenol (DON), zearalenone (ZEA), ergosterol (EGS), dry matter (DM), 200 kernel weight, Kjeldahl nitrogen (N), ether extract, ash, sugar, starch, acid and neutral detergent fibre (ADF, NDF, respectively), cellulose, hemicellulose and lignin. The true metabolisable energy (TME), TME corrected to zero N balance (TME_n), true available amino acid (TAAA) and true DM digestibility (TDMD) contents of these samples and corn to which 4, 16 or 64 mg purified DON kg^?1 were added, were determined using adult White Leghorn chickens. The DON, ZEA, EGS, N and ash contents were higher (P<0.001), and ether extract, TME and TME_n values were lower (p<0.01) in F3 than in Fl. Higer avilabilites accured for aspartic and glutamic acids, isoleucine, leucine and histidine in F2 and F3 than F1 (P<0.05). Carbohydrate and fibre values varied little (p>0.05) among fractions either within or among incoulation treatments. Sources of Fusarium inoculate influenced (P<0.05) the DON, ZEA, N, fat and TDMD of the corn. The TME_n and total TAAA of corn decreased (P<0.001) when purified DON was added. Moderate relationships (r=0.57?0.73) occurred between DON and ZEA, EGS and N. In general, these results are similar to those for wheat, and indicate that chemical and nutritive content of feedingstuffs may be increased when they are infected by toxigenic fungi.     

Human placental cytotrophoblasts produce the immunosuppressive cytokine interleukin 10

The mechanism by which the mammalian mother accepts the implanting fetus as an allograft remains unexplained, but is likely to be the result of a combination of factors. Mononuclear cytotrophoblasts, the specialized fetal cells of the placenta that invade the uterus, play an important role. These cells express HLA-G, an unusual major histocompatibility complex class I-B molecule, and secrete cytokines and pregnancy-specific proteins that can regulate immune function. We investigated whether cytotrophoblasts secrete interleukin 10 (IL-10), a cytokine that potently inhibits alloresponses in mixed lymphocyte reactions. Cytotrophoblasts from all stages of pregnancy produced IL-10 in vitro, but neither placental fibroblasts nor choriocarcinoma (malignant trophoblast) cell lines did so. Spontaneous IL-10 production averaged 650, 853, and 992 pg/10(6) cells in the first, second, and third trimesters of pregnancy, respectively. IL-10 secretion dropped approximately 10-fold after the first 24 h of culture, and was paralleled by a decrease in messenger RNA. IL-10 messenger RNA was detected in biopsies of the placenta and the portion of the uterus that contains invasive cytotrophoblasts, suggesting that this cytokine is also produced in vivo. IL-10 secreted by cytotrophoblasts in vitro is bioactive, as determined by its ability to suppress interferon gamma production in an allogeneic mixed lymphocyte reaction. We conclude that human cytotrophoblast IL-10 may be an important factor that contributes to maternal tolerance of the allogeneic fetus.     

Control of Leishmania major by a monoclonal alpha beta T cell repertoire

Little is known regarding the diversity of the host T cell response that is required to maintain immunologic control of microbial pathogens. Leishmania major persist as obligate intracellular parasites within macrophages of the mammalian host. Immunity is dependent upon activation of MHC class II-restricted T cells to an effector state capable of restricting growth and dissemination of the organisms. We generated alpha-beta Leishmania-specific (ABLE) TCR transgenic mice with MHC class II-restricted T cells that recognized an immunodominant Leishmania Ag designated LACK. Naive T cells from ABLE mice proliferated in vitro after incubation with recombinant LACK or with Leishmania-parasitized macrophages and in vivo after injection into infected mice. Infected ABLE mice controlled Leishmania infection almost as well as wild-type mice despite a drastic reduction in the T cell repertoire. ABLE mice were crossed to mice with disruption of the TCR constant region alpha gene to create animals with a single alpha beta T cell repertoire. Although mice deficient in all alpha beta T cells (TCR-C alpha 0 mice) failed to control L. major, mice with a monoclonal alpha beta T cell repertoire (ABLE TCR-C alpha 0 mice) displayed substantial control. The immune system is capable of remarkable efficiency even when constrained to recognition of a single epitope from a complex organism.     

Interferon gamma derived from CD4(+) T cells is sufficient to mediate T helper cell type 1 development

Interferon gamma (IFN-gamma) has been implicated in T helper type 1 (Th1) cell development through its ability to optimize interleukin 12 (IL-12) production from macrophages and IL-12 receptor expression on activated T cells. Various systems have suggested a role for IFN-gamma derived from the innate immune system, particularly natural killer (NK) cells, in mediating Th1 differentiation in vivo. We tested this requirement by reconstituting T cell and IFN-gamma doubly deficient mice with wild-type CD4(+) T cells and challenging the mice with pathogens that elicited either minimal or robust IL-12 in vivo (Leishmania major or Listeria monocytogenes, respectively). Th1 cells developed under both conditions, and this was unaffected by the presence or absence of IFN-gamma in non-T cells. Reconstitution with IFN-gamma-deficient CD4(+) T cells could not reestablish control over L. major, even in the presence of IFN-gamma from the NK compartment. These data demonstrate that activated T cells can maintain responsiveness to IL-12 through elaboration of endogenous IFN-gamma without requirement for an exogenous source of this cytokine.     

Sex stereotypes and social judgment.

Tested the assumption that sexual stereotypic beliefs affect the judgments of individuals in an experiment with 98 male and 97 female undergraduates. No evidence was found for effects of stereotypes on Ss' judgments about a target individual. Instead, Ss judgments were strongly influenced by behavioral information about the target. To explain these results, it is noted that the predicted effects of social stereotypes on judgments conform to Bayes' theorem for the normative use of prior probabilities in judgment tasks, inasmuch as stereotypic beliefs may be regarded as intuitive estimates for the probabilities of traits in social groups. Research in the psychology of prediction has demonstrated that people often neglect prior probabilities when making predictions about people, especially when they have individuating information about the person that is subjectively diagnostic of the criterion. An implication of this research is that a minimal amount of subjectively diagnostic target case information should be sufficient to eradicate effects of stereotypes on judgments. Results of a 2nd experiment with 75 female and 55 male undergraduates support this argument. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effectiveness of density segregation and sodium carbonate treatment on the detoxification of Fusarium-contaminated corn fed to growing pigs

The effectiveness of using rinsing, density segregation or 0.1 M sodium carbonate treatments of Fusarium-contaminated corn containing deoxynivalenol (DON) and zearalenone were tested both chemically and by feeding the material to growing pigs. Uninfected and Fusarium graminearum-inoculated corn (containing 40.3 mg DON and 0.94 mg zearalenone kg^?1cor) were subjected to various treatments: no treatment (control), rinsed, rinsed and all floating material removed, soaked in 0.1 M sodium carbonate for 24 h or soaked in 0.1 M sodium carbonate for 24 h after removal of the floating material. All corn samples were analysed for DON and zearalenone. Rinsing the contaminated corn reduced the concentrations of both mycotoxins by 44% while soaking in 0.1 M sodium carbonate reduced the toxin concentrations an additional 35%. In both cases, removal of the floating material decreased concentrations another 8 and 4%, respectively. In the feeding study, 10-week-old barrows were fed diets containing 17.5% of the treated corn samples over a 21 day period. Daily feed consumption and weight gains were significantly improved in pigs fed the rinsed-minus-floating corn and the sodium carbonate-soaked corn with and without floating material compared to the untreated contaminated corn. The chemical and biological data demonstrated that rinsing combined with the removal of floating material or soaking in 0.1 M sodium carbonate with or without removal of floating material were effective in reducing the toxicity of the contaminated corn. Due to a higher energy requirement needed to dry the corn soaked in sodium carbonate, the combination of rinsing and removal of the floating material is recommended as a more general and practical method of detoxification of contaminated grain.     

Immunological tolerance to a pancreatic antigen as a result of local expression of TNFalpha by islet beta cells

Recent experiments have suggested that tumor necrosis factor alpha (TNFalpha) can down-regulate islet-specific T cells and prevent the development of autoimmune diabetes. Here we demonstrate that transgenic mice expressing both TNFalpha and the Leishmania major LACK antigen in the pancreas (RIP-TNFalpha/RIP-LACK) exhibit an impaired ability to mount a CD4+ T cell response against LACK. In addition, peripheral CD4+ T cells from TCR transgenic mice (TCR-LACK/RIP-TNFalpha/RIP-LACK) produced reduced interleukin-2 but elevated levels of T helper 2 cytokines in response to LACK peptide in vitro. Taken together, our data suggest that TNFalpha may act in vivo to modulate a potentially damaging self-reactive T cell response by inducing tolerance to pancreatic antigens.     

Social categorization and discriminatory behavior: Extinguishing the minimal intergroup discrimination effect.

Previous research on the minimal intergroup discrimination effect suggests that (a) apparently random social categorization may be sufficient to induce differential responses toward similarly and dissimilarly categorized others and (b) perceived categorical similarity (or intragroup vs intergroup comparisons) may be the basis for the effect. Four experiments were conducted with 227 undergraduates to provide 2 independent tests of the hypotheses. Exps I and II demonstrated that social categorization resulting from a lottery procedure was sufficient to elicit differential allocation of chips to and differential social evaluation of in- and out-group members. Exp III and IV demonstrated that both information about the reward value of the in-group and information about the reward value of the out-group had an impact on Ss' discriminatory behavior. The directions of the effects were opposite: rewards from the in-group increased and those from the out-group decreased discriminatory behavior. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)