Research Article Clinical and Diagnostic Pathology Clin Diagn Pathol, 2017 doi: 10.15761/CDP.1000112 Volume 1(3): 1-4 CD56 and CD3 expression in the liver and spleen of dogs with visceral leishmaniasis Pamela Rodrigues Reina Moreira 1 *, Paulo Henrique Leal Bertolo 2 and Rosemeri de Oliveira Vasconcelos 2 1 Postgraduate Veterinary Medicine Program, FCAV/UNESP (Faculdade de Ciências Agrárias e Veterinárias - Univ. Estadual Paulista), Via de Acesso Prof. Paulo Donato Castellane, s/n, Jaboticabal, São Paulo, Brazil 2 Department of Veterinary Pathology, FCAV/UNESP, Jaboticabal, São Paulo, Brazil Abstract NKT cells are a subpopulation of lymphocytes with NK cell (CD56+) and T lymphocytes (CD3+) characteristics. Tese cells may to exterminate the infected cells and play an essential role in innate immunity. Te objective of the present study was, through the immune histo-chemical technique, to analyze the livers and spleens of dogs with VL, considering the presence of parasites, CD56 and CD3 imuno detection. A total of 71 naturally infected dogs (infected group) from an endemic area for VL was used. A control group (C=10) was obtained from a not endemic area for VL. In the parasite load analysis, both liver and spleen showed no signifcant diference in the infected dogs. Te immune detection of CD56 was low and not difer between the infected and control groups (P=0.7787) in liver. However, in spleen there were signifcant diferences (P=0.0385) between infected (median=3.40) and control groups (median=13.70). CD3 showed signifcant diferences in the liver (P=0.0229) of the infected (median=42.40) and control (median=7.90). In spleen these diference occurred between (P=0.0081) infected (median=51.0) and control groups too (median=381.0). Tus, we suggest that in the spleen and liver of infected dogs, the expression of CD56 and CD3 cells did not play a cytotoxic efect on parasitized macrophages in infected dogs. Te proportion of CD56+ and CD3+ phenotypes was low in the infected group, suggesting that this cytotoxic way seems not to be efciently activated in dogs with VL, regardless of the parasite load of each organ. Correspondence to: Pamela Rodrigues Reina Moreira, FCAV/UNESP (Faculdade de Ciências Agrárias e Veterinárias - Univ. Estadual Paulista), Via de Acesso Prof. Paulo Donato Castellane, s/n, Jaboticabal, São Paulo, Brazil, Tel: 55-16-3209-7368, E-mail: pamela_rreina@yahoo.com.br Key words: innate immunity, Leishmania infantum, compartmentalized immune response. Received: April 18, 2017; Accepted: May 19, 2017; Published: May 23, 2017 Introduction In addition to macrophages, NK cells (innate immunity), can play an important role in defending hosts against injuries. Tese cells are cytotoxic lymphocytes that fght viral infections and tumors, without the need for previous recognition of a specifc antigen [1]. NK cells have receptors for CD56 in their cytoplasmic membrane and have no expression of CD3 [1,2]. A small population of T lymphocytes also express markers that are found on NK cells, such as CD56, and are known as NKT cells, which regulate the immune response. NKT cells are a subset of lymphocytes that presenting NK cell and T cells (CD56+ CD3+) characteristics, that perform both cell functions in innate immunity and in the adaptive response. Probably these cells represent a primitive form and conserved immunity [3,4]. Tese NKT cells are capable of produce cytokines, such as IL-4 and IFN-γ, contributing to the host defense against pathogens [5]. Cells that just express CD56 and do not express CD3, are called natural killer cells, that secrete IL-2, IL-12, TNF-α and IFN-γ and stimulating the cytotoxic action and destroying the infected cells, through of an increased expression of Fas ligand that activates apoptosis [6]. NK cells also induce target cell death by the release of granules and of cytotoxic proteins, that induce o Fas ligand to apoptosis, that is, they do not destroy microorganisms directly, but act on infected or neoplastic cells, through mechanisms similar to the mechanisms of CD8 T lymphocytes, through degranulation and release of enzymes that activate apoptosis of target cells [1,2,6]. Tus, the objective of the present study was to evaluate the presence of CD56 and CD3 in the spleen and liver of dogs with VL and compare these fndings with the density of parasitized macrophages in dogs with VL. Material and methods Material Te dogs used in this study were originated from the Zoonosis Control Center (Araçatuba, São Paulo State, Brazil), an endemic area for canine VL [7,8]. Seventy-one Leishmania infantum – infected dogs were used, without preference for age, breed or sex. Te dogs were euthanazied according to decree number 51.838 of the Brazilian Ministry of Health and Resolution number 714, of June 20, 2002, of the Federal Veterinary Medicine Council. Necropsy was performed immediately afer the dogs’ death. Te control group consisted of ten dogs from non-endemic area for VL [9], free of systemic pathological processes, such as systemic infection or cancer. Infected and control dogs were selected, following confrmation or not of VL, by RIFI and ELISA and the presence or absence of the parasite DNA was confrmed by means of RT-PCR. Liver and spleen fragments were collected and fxed in 10% formalin solution, for the immunohistochemical analysis, where we evaluated the immunostaining of CD56, CD3 and parasite load.