Exposure of Ancistrus multispinis (Regan, 1912, Pisces, Teleostei) to deltamethrin: Effects on cellular immunity Cla ´ udia Turra Pimpa ˜o a , Aleksander Roberto Zampronio b , Helena Cristina Silva de Assis b, * a Programa de Po ´s graduaça ˜o em Processos Biotecnolo ´gicos, Universidade Federal do Parana ´, Curitiba, PR, Brazil b Departamento de Farmacologia, Universidade Federal do Parana ´, P.O. Box 19031, 81530-990 Curitiba, PR, Brazil article info Article history: Received 16 September 2007 Received in revised form 19 July 2008 Accepted 20 July 2008 Available online 26 July 2008 Keywords: Deltamethrin Ancistrus multispinis LPS Leukocytes’ migration Macrophage abstract The objective of this study performed in Ancistrus multispinis was to evaluate whether sublethal doses of deltamethrin (DM) could affect lipopolysaccharide (LPS)-induced leukocyte migration to the peritoneal cavity and the production of nitric oxide (NO) by kidney macrophages exposed to LPS and/or DM. For cell migration studies, 10 fish were exposed to DM 0.1 or 0.3 mg kg 1 or vehicle for 96 h. After this period, each group received LPS (0.1 mg kg 1 ) or saline and the cells were collected after 4 h. For the production of NO, kidney macrophages were isolated from eight fish and the cells were incubated for 24 or 48 h with LPS (10 mg mL 1 ) and DM (0.3 and 1 mg mL 1 ). The results were analyzed using ANOVA followed by Bonferroni multiple comparisons test. A small leukocyte population (530  30.8 cells mL 1 ) was naturally observed in the peritoneal cavity, however after inoculation of LPS, the number of leukocytes was increased by 157%. For the fish treated with DM 0.1 and 0.3 mgkg 1 , total leukocytes had increased by 100 and 162%, respectively. The combination of LPS with the higher dose of DM showed a potentiating or additive effect. The production of NO was increased in all the treated groups in relation to the control group. The group DM 1 mg mL 1 was also increased in relation to other groups. The ‘‘in vitro’’ method can be used to evaluate the potential effects of toxic agents on the fish immune system. Therefore, we can conclude that DM could increase the NO production of A. multispinis. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Similar to other vertebrates, fish respond to infectious agents in both specific and nonspecific manner and appear to have similar cellular and humoral immune components as warm-blooded vertebrates. The first and often most important responses of fish to infectious agents are nonspecific [1,2]. Pathogen-induced activation of the host cell-death pathway may, in turn, eliminate key immune cells, thereby evading host defences that otherwise would act to limit infection [3]. Induction of host cell apoptosis by bacteria has been suggested as an important process in the pathogenesis of some infections, since elimination of immune cells can facilitate invasion and spreading of the infectious agent [3,4]. In mammals, the inflammatory response sets into motion a complex series of events, with the objective to limit the tissue injury and/or eliminate the infectious agent to finally heal and reconstitute damaged tissue [5]. The cellular infiltrate at the inflammatory site primarily involves polymorphonuclear neutro- phils and macrophages. Neutrophil adhesion and accumulation are the early prerequisites of acute inflammation whereas macrophage accumulation occurs later. Although chemotaxis is an important factor in neutrophil migration, it is accepted that the communication between neutrophils and endothelial cells is more interactive and complex. Highly regulated expression of cell adhesion molecules on neutrophils and endothelial cells is required for adhesion [6]. Macrophages are also considered as important cells in disease resistance of fish. They are the main phagocytic cells in fish while granulocytes are weak or non-phagocytic [2,7,8]. Modulation of fish macrophage activity by environmental contaminants has also been reported, with diverse effects, depending on the dose and chemical type of the contaminant [9–11]. To date, the majority of the studies on the biology of fish macrophages have been performed using primary cultures, estab- lished following isolation of the cells from the kidneys of fish [8,12,13]. Despite high variability in the response of macrophages in primary cultures, the evidence suggests a remarkable morpholog- ical and patho-physiological similarity between fish, mammalian and avian macrophages [2,14,15]. In mammalian macrophages, nitric oxide (NO) can be produced in response to cytokines, bacterial lipopolysaccharide (LPS) or parasites by inducible NO synthases (iNOS) [16]. In fish macro- phages, production of NO by LPS has been demonstrated in goldfish, catfish and turbot [17–19]. * Corresponding author. Fax: þ55 41 32662042. E-mail address: helassis@ufpr.br (H.C. Silva de Assis). Contents lists available at ScienceDirect Fish & Shellfish Immunology journal homepage: www.elsevier.com/locate/fsi 1050-4648/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.fsi.2008.07.012 Fish & Shellfish Immunology 25 (2008) 528–532