Full length article Fat-associated lymphoid cluster in Cyprinus carpio: Characterisation and its relation with peritoneal haemangiosarcoma Q2,7 Q6 Ruth L. Madera-Sandoval a , Elba Reyes-Maldonado b , Ricardo Dzul-Caamal a , Esperanza Gallegos-Rangel a , María Lilia Domínguez-L opez c , Ethel García-Latorre c , Armando Vega-L opez a, * a Laboratorio de Toxicología Ambiental, Departamento de Ingeniería en Sistemas Ambientales, Av. Wilfrido Massieu s/n, Unidad Profesional Zacatenco, Mexico, D.F. CP 07738, Mexico Q3 b Laboratorio de Citología, Departamento de Morfología, Escuela Nacional de Ciencias Biologicas, Instituto Politecnico Nacional, Carpio y Plan de Ayala s/n, Casco de Santo Tomas, Mexico, D.F. CP 11340, Mexico c Laboratorio de Inmunoquímica I, Departamento de Inmunología, Escuela Nacional de Ciencias Biologicas, Instituto Politecnico Nacional, Carpio y Plan de Ayala s/n, Casco de Santo Tomas, Mexico, D.F. CP 11340, Mexico article info Article history: Received 11 December 2014 Received in revised form 21 February 2015 Accepted 14 March 2015 Available online xxx Keywords: C-kit CD45 FALC cells IL7R Sca-1 Proto-oncogenes Th-2 cytokines abstract FALC cells are natural helper cells producing Th2-type cytokines, which express c-kit, Sca-1, IL7R and CD45 in mouse and human. These cells are involved in allergic responses and contribute to the in- ammatory reactions of adipose tissue; however, a lack of information prevails about the presence of these cells in other species. The aim of the study was to identify and characterise FALC cells in the common carp (Cyprinus carpio) using immunohistochemistry and molecular biology techniques as well as to explore their relationships with their microenvironment. Histological description of the FALC was performed using H&E and polyclonal antibodies were used against cell-surface markers such as c-kit, Sca-1 and CD45. Furthermore, gene expression of c-kit, Sca-1 and IL7R was assessed. C. carpio FALC cells express the same surface markers reported in FALC of the mouse at both the pre- and post- transcriptional level. By exposure to the soluble fraction of helminths, FALC cells produce abundant Th2 cytokines (IL-5, IL-6 and IL-13) but do not synthesise IL-1a. Additionally, FALC cells probably participate in vascular remodelling of the intestine vessels, inducing tumours because a malignant haemangiosarcoma in the peritoneal cavity was found. In this tumour, abundant FALC with their char- acteristic cell-surface markers were detected. The ndings of this study suggest the involvement of some proto-oncogenes such as c-kit and Sca-1, and the deregulation of Src kinases modulated by CD45 present in C. carpio FALC with the ontogeny of peritoneal haemangiosarcoma in this sh species. © 2015 Published by Elsevier Ltd. 1. Introduction Since 2001, new lymphocytes of innate immunity Th2 type have been reported [24]. These lymphocytes do not have germline (CD3) but it is possible to identify their cytokines as well as the stimuli involved in this expression [47]. From those dates, the innate immunity was conceived as a set of processes that entails a nonspecic mechanism of defence, physical barriers, but mostly effector cells that can produce and/or stimulate cytokines [56]. In this way, it is possible to conceive the intricate balance between the innate and adaptive systems to achieve the defence of the body. However, in 2010, a new nding about the link between innate and adaptive response was documented. An innate lymphocyte present in a novel lymphoid structure associated with adipose tissues in the mouse peritoneal cavity named FALC(fat- associated lymphoid cluster) was found [47]. These FALC cells are natural helper cells (NHC) that are able to elicit a cytotoxic response against primary infections; however, they do not have antigen receptors. FALC cells express c-kit [47], a tyrosine-protein kinase that acts as a cell-surface receptor for KITLG/SCF and plays an essential role in the regulation of cell survival and proliferation, haematopoiesis and stem cell maintenance [7,69]. These cells ex- press Sca-1 or Ly6A (lymphocyte antigen 6 complex, locus A), which is also known as stem cell antigen-1 [26]. The lymphocyte * Corresponding author. E-mail address: avegadv@yahoo.com.mx (A. Vega-Lopez). Contents lists available at ScienceDirect Fish & Shellsh Immunology journal homepage: www.elsevier.com/locate/fsi http://dx.doi.org/10.1016/j.fsi.2015.03.019 1050-4648/© 2015 Published by Elsevier Ltd. Fish & Shellsh Immunology xxx (2015) 1e9 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 YFSIM3373_proof 26 March 2015 1/9 Please cite this article in press as: R.L. Madera-Sandoval, et al., Fat-associated lymphoid cluster in Cyprinus carpio: Characterisation and its relation with peritoneal haemangiosarcoma, Fish & Shellsh Immunology (2015), http://dx.doi.org/10.1016/j.fsi.2015.03.019