**Neutrophils Plasticity: The Regulatory Interface in Various Pathological Conditions**

Suelen Martins Perobelli,

Triciana Gonçalves Silva and Adriana Bonomo

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/68130

#### **Abstract**

It is now known that neutrophils make up a population of complex cells with great plasticity, challenging the old view of neutrophil association with tissue damage and early phases of infection. Here, we discuss different contexts in which these cells can induce anti-inflammatory responses. Although distinct surface markers and cytokines profiles were shown, the most reliable characterization of suppressor neutrophil subtypes relies on their functional characteristics. One important example of inhibitory neutrophils generation comes from in vivo treatment with G-CSF, for 5 days, as for hematopoieticstem-cell-transplantation (HSCT). In this case,donor blood is enriched in degranulated granulocytes harboring a functional regulatory phenotype, characterized by IL-10 production. These cells, when transferred together with HSCT, are able to reduce graft-versus-host-disease, being influenced by Treg cells and influencing them back. Importantly, this protection is long lasting and specific, keeping immunocompetence to other antigens. This regulation is paramount in HSCT, and represents a simple approach to be applied in humans. In summary, we discuss the interaction of neutrophils with other cell types and its consequence in immunomodulation. We believe these features confer an important bridge between innate and adaptive immune system, building a new knowledge for an underestimated cell type.

**Keywords:** regulatory neutrophils, neutrophils subtypes, T cell inhibition, Cytokines, G-CSF, GVHD

© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
