Neutrophils and immunity: challenges and opportunities.

Department of Microbiology and Immunology, Weill Cornell Medical College, Weill Graduate School of Medical Sciences of Cornell University, Box 57, 1300 York Avenue, New York 10021, USA.
Nature reviews. Immunology (Impact Factor: 33.84). 04/2006; 6(3):173-82. DOI: 10.1038/nri1785
Source: PubMed

ABSTRACT Scientists who study neutrophils often have backgrounds in cell biology, biochemistry, haematology, rheumatology or infectious disease. Paradoxically, immunologists seem to have a harder time incorporating these host-defence cells into the framework of their discipline. The recent literature discussed here indicates that it is appropriate for immunologists to take as much interest in neutrophils as in their lymphohaematopoietic cousins with smooth nuclei. Neutrophils inform and shape immune responses, contribute to the repair of tissue as well as its breakdown, use killing mechanisms that enrich our concepts of specificity, and offer exciting opportunities for the treatment of neoplastic, autoinflammatory and autoimmune disorders.

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    ABSTRACT: Aim: The present study was designed to evaluate the neutrophil dynamics in terms of the functional competence during subclinical mastitis (SCM) and clinical mastitis (CM). Materials and Methods: A total of 146 Karan fries cows were screened and were divided into three groups as control (n=12), SCM, n=12 and CM, n=12 groups on the basis of California mastitis test scoring, bacteriological evaluation, gross and morphological changes in milk and by counting milk somatic cell count (SCC). Both blood and milk polymorphonuclear neutrophils (PMNs) were isolated in the study. Phagocytic activity (PA) was studied by spectrophotometrically; neutrophil extracelluar traps (NETs) were studied by scanning electron microscopy (SEM); CD44 was quantified by flow cytometry and apoptosis was studied by fluorescent microscopy. Results: Significantly (p<0.05) higher SCC, PA was found in milk of CM cows as compared to SCM and control cows. Significantly lower (p<0.05) apoptosis was observed in PMNs isolated from both blood and milk of CM group of cows when compared to control and SCM group. The milk neutrophils of CM group of cows formed NETs as evidenced from the SEM images. Surface expression of CD44 revealed a significantly (p<0.05) lower expression in milk neutrophils of CM group of cows when compared to SCM and control group of cows. Conclusion: The study indicated a positive correlation between delayed neutrophil apoptosis, persistent staying of neutrophils at the site of infection along with formation of NETs as the strategies to fight against the pathogens in the udder during Staphylococcal mastitis. The study forms a strong base for future molecular research in terms of neutrophil recruitment and neutrophil removal from the site of infection.
    Veterinary World 03/2015; 8(3). DOI:10.14202/vetworld.2015.336-345
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    ABSTRACT: Neutrophils are the first line of defense against invading pathogens and are rapidly recruited to the sites of Leishmania inoculation. During Leishmania braziliensis infection, depletion of inflammatory cells significantly increases the parasite load whereas co-inoculation of neutrophils plus L. braziliensis had an opposite effect. Moreover, the co-culture of infected macrophages and neutrophils also induced parasite killing leading us to ask how neutrophils alone respond to an L. braziliensis exposure. Herein we focused on understanding the interaction between neutrophils and L. braziliensis, exploring cell activation and apoptotic fate. Inoculation of serum-opsonized L. braziliensis promastigotes in mice induced neutrophil accumulation in vivo, peaking at 24 h. In vitro, exposure of thyoglycollate-elicited inflammatory or bone marrow neutrophils to L. braziliensis modulated the expression of surface molecules such as CD18 and CD62L, and induced the oxidative burst. Using mCherry-expressing L. braziliensis, we determined that such effects were mainly observed in infected and not in bystander cells. Neutrophil activation following contact with L. braziliensis was also confirmed by the release of TNF-α and neutrophil elastase. Lastly, neutrophils infected with L. braziliensis but not with L. major displayed markers of early apoptosis. We show that L. braziliensis induces neutrophil recruitment in vivo and that neutrophils exposed to the parasite in vitro respond through activation and release of inflammatory mediators. This outcome may impact on parasite elimination, particularly at the early stages of infection.
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    ABSTRACT: Neutrophils are highly motile phagocytic cells that play a critical role in the immune response to infection. Zebrafish (Danio rerio) are increasingly used to study neutrophil function and host-pathogen interactions. The generation of transgenic zebrafish lines with fluorescently labeled leukocytes has made it possible to visualize the neutrophil response to infection in real time by use of optically transparent zebrafish larvae. In addition, the genetic tractability of zebrafish has allowed for the generation of models of inherited neutrophil disorders. In this review, we discuss several zebrafish models of infectious disease, both in the context of immunocompetent, as well as neutrophil-deficient hosts and how these models have shed light on neutrophil behavior during infection. © Society for Leukocyte Biology.


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