Browsing by Subject "B cells"

Now showing 1 - 5 of 5
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    Open Access
    IL-4Rα-associated antigen processing by B cells promotes immunity in Nippostrongylus brasiliensis infection
    (Public Library of Science, 2013) Horsnell, William G C; Darby, Matthew G; Hoving, Jennifer C; Nieuwenhuizen, Natalie; McSorley, Henry J; Ndlovu, Hlumani; Bobat, Saeeda; Kimberg, Matti; Kirstein, Frank; Cutler, Anthony J
    In this study, B cell function in protective TH2 immunity against N. brasiliensis infection was investigated. Protection against secondary infection depended on IL-4Rα and IL-13; but not IL-4. Protection did not associate with parasite specific antibody responses. Re-infection of B cell-specific IL-4Rα−/− mice resulted in increased worm burdens compared to control mice, despite their equivalent capacity to control primary infection. Impaired protection correlated with reduced lymphocyte IL-13 production and B cell MHC class II and CD86 surface expression. Adoptive transfer of in vivo N. brasiliensis primed IL-4Rα expressing B cells into naïve BALB/c mice, but not IL-4Rα or IL-13 deficient B cells, conferred protection against primary N. brasiliensis infection. This protection required MHC class II compatibility on B cells suggesting cognate interactions by B cells with CD4+ T cells were important to co-ordinate immunity. Furthermore, the rapid nature of these protective effects by B cells suggested non-BCR mediated mechanisms, such as via Toll Like Receptors, was involved, and this was supported by transfer experiments using antigen pulsed Myd88−/− B cells. These data suggest TLR dependent antigen processing by IL-4Rα-responsive B cells producing IL-13 contribute significantly to CD4+ T cell-mediated protective immunity against N. brasiliensis infection.
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    Open Access
    Inducible deletion of CD28 prior to secondary nippostrongylus brasiliensis infection impairs worm expulsion and recall of protective memory CD4 (+) T cell responses
    (Public Library of Science, 2014) Ndlovu, Hlumani; Darby, Mathew; Froelich, Monika; Horsnell, William; Lühder, Fred; Hünig, Thomas; Brombacher, Frank
    IL-13 driven Th2 immunity is indispensable for host protection against infection with the gastrointestinal nematode Nippostronglus brasiliensis. Disruption of CD28 mediated costimulation impairs development of adequate Th2 immunity, showing an importance for CD28 during the initiation of an immune response against this pathogen. In this study, we used global CD28−/− mice and a recently established mouse model that allows for inducible deletion of the cd28 gene by oral administration of tamoxifen (CD28−/loxCre+/−+TM) to resolve the controversy surrounding the requirement of CD28 costimulation for recall of protective memory responses against pathogenic infections. Following primary infection with N. brasiliensis, CD28−/− mice had delayed expulsion of adult worms in the small intestine compared to wild-type C57BL/6 mice that cleared the infection by day 9 post-infection. Delayed expulsion was associated with reduced production of IL-13 and reduced serum levels of antigen specific IgG1 and total IgE. Interestingly, abrogation of CD28 costimulation in CD28−/loxCre+/− mice by oral administration of tamoxifen prior to secondary infection with N. brasiliensis resulted in impaired worm expulsion, similarly to infected CD28−/− mice. This was associated with reduced production of the Th2 cytokines IL-13 and IL-4, diminished serum titres of antigen specific IgG1 and total IgE and a reduced CXCR5+ TFH cell population. Furthermore, total number of CD4+ T cells and B220+ B cells secreting Th1 and Th2 cytokines were significantly reduced in CD28−/− mice and tamoxifen treated CD28−/loxCre+/− mice compared to C57BL/6 mice. Importantly, interfering with CD28 costimulatory signalling before re-infection impaired the recruitment and/or expansion of central and effector memory CD4+ T cells and follicular B cells to the draining lymph node of tamoxifen treated CD28−/loxCre+/− mice. Therefore, it can be concluded that CD28 costimulation is essential for conferring host protection during secondary N. brasiliensis infection.
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    Open Access
    Investigating role of IL-4 receptor alpha (IL-4Ra) in murine models of atopic dermatitis
    (2021) Scibiorek, Martyna; Brombacher, F; Hadebe, S
    Atopic dermatitis (AD) is a common pruritic inflammatory skin disease with complex environmental and genetic predisposition factors. Primary skin barrier dysfunction and aberrant T helper 2 (TH2) responses to common allergens, together with increased serum IgE antibodies, characterise the disease. B and T cells are essential in the disease manifestation, however, the exact mechanism of how these cells are involved in skin sensitization to allergens is unclear. Clinical studies investigating the efficacy of monoclonal antibody to IgE such as omalizumab and ligelizumab do not show efficacy in AD patients. However, targeting IL-4/IL-13 signalling axis with dupilumab show efficacy in AD. We investigated the importance of interleukin 4 receptor alpha (IL- 4Rα) signalling specifically on B and T cells to understand the requirement of this signalling axis in epicutaneous skin sensitisation during AD. We investigated 3 models of AD using House dust mite (HDM), Ovalbumin (OVA) and low-calcemic analog of vitamin D (MC903) on mouse strains lacking IL-4Ra on various B and T cells. We used mb1creIL-4Rα-/lox (mice lacking IL-4Rα on B cells), iLcKCre IL-4Rα-/lox (mice lacking IL-4Rα on all T cells), LcKCre IL-4Rα-/lox (mice lacking IL-4Rα on CD4+ and CD8+ T cells), CD4Cre IL-4Rα-/lox (mice lacking IL-4Rα on CD4+ Tcells), Foxp3Cre IL-4Rα-/lox (mice lacking IL-4Rα on Foxp3+ T regulatory cells) and IL-4Rα-/lox littermate controls. We analysed cellular infiltrate in the skin and inguinal lymph nodes (LN) by flow cytometry, histology of the skin, serum antibodies and cytokines by ELISA. Mice lacking IL-4Rα-responsive B cells showed a reduced serum IgE levels, but no significant differences in epidermal thickening compared to littermate control in HDM or MC903 models. Mice investigated in the T cell arm of the study showed reduced epidermal thickening in pan-T cell IL-4Rα knock-out, but not in groups lacking IL-4Rα signalling in adaptive T cells, suggesting importance of IL4/IL13 signalling axis in ydT cells during AD. Overall, our results suggest that deletion of IL-4Rα on innate T cells regulates inflammatory response in atopic dermatitis.
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    Open Access
    Optimizing viable leukocyte sampling from the female genital tract for clinical trials: an international multi-site study
    (Public Library of Science, 2014) McKinnon, Lyle R; Hughes, Sean M; De Rosa, Stephen C; Martinson, Jeffrey A; Plants, Jill; Brady, Kirsten E; Gumbi, Pamela P; Adams, Devin J; Vojtech, Lucia; Galloway, Christine G
    BACKGROUND: Functional analysis of mononuclear leukocytes in the female genital mucosa is essential for understanding the immunologic effects of HIV vaccines and microbicides at the site of HIV exposure. However, the best female genital tract sampling technique is unclear. Methods and FINDINGS: We enrolled women from four sites in Africa and the US to compare three genital leukocyte sampling methods: cervicovaginal lavages (CVL), endocervical cytobrushes, and ectocervical biopsies. Absolute yields of mononuclear leukocyte subpopulations were determined by flow cytometric bead-based cell counting. Of the non-invasive sampling types, two combined sequential cytobrushes yielded significantly more viable mononuclear leukocytes than a CVL (p<0.0001). In a subsequent comparison, two cytobrushes yielded as many leukocytes (∼10,000) as one biopsy, with macrophages/monocytes being more prominent in cytobrushes and T lymphocytes in biopsies. Sample yields were consistent between sites. In a subgroup analysis, we observed significant reproducibility between replicate same-day biopsies (r = 0.89, p = 0.0123). Visible red blood cells in cytobrushes increased leukocyte yields more than three-fold (p = 0.0078), but did not change their subpopulation profile, indicating that these leukocytes were still largely derived from the mucosa and not peripheral blood. We also confirmed that many CD4 + T cells in the female genital tract express the α4β7 integrin, an HIV envelope-binding mucosal homing receptor. CONCLUSIONS: CVL sampling recovered the lowest number of viable mononuclear leukocytes. Two cervical cytobrushes yielded comparable total numbers of viable leukocytes to one biopsy, but cytobrushes and biopsies were biased toward macrophages and T lymphocytes, respectively. Our study also established the feasibility of obtaining consistent flow cytometric analyses of isolated genital cells from four study sites in the US and Africa. These data represent an important step towards implementing mucosal cell sampling in international clinical trials of HIV prevention.
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    The role of B-cells and IgM antibodies in parasitemia, anemia, and VSG switching in Trypanosoma brucei-infected mice
    (Public Library of Science, 2008) Magez, Stefan; Schwegmann, Anita; Atkinson, Robert; Claes, Filip; Drennan, Michael; De Baetselier, Patrick; Brombacher, Frank
    Author Summary African trypanosomiasis is a disease caused by different species of extracellular flagellated protozoan trypanosome parasites. Trypanosomes have developed a mechanism of regular antigenic variation of their variant-specific surface glycoprotein (VSG) coat which allows chronic infection. Replacement of this coat occurs at rapid regular time intervals, allowing the parasite to escape from an effective host antibody responses. So far, primary T-cell independent antibody responses have been described to constitute the main host defense mechanism, relying largely on IgM antibody induction. Using genetically engineered B lymphocyte- or IgM-deficient mouse strains, we show that lack of B-cells or IgM did not prevent infection-associated anemia. More importantly, we show that in the absence of IgM, parasitemia was controlled almost as well as in wild-type mice, with only slightly increased mortality. In addition, we show in vivo that antigenic variation is not affected by the lack of IgM.