Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/dci SHORT COMMUNICATION Quantitation of leukocyte gene expression in cetaceans Tatjana Sitt à , Lizabeth Bowen, Myra T. Blanchard, Brett R. Smith, Laurel J. Gershwin, Barbara A. Byrne, Jeffrey L. Stott à School of Veterinary Medicine, Department of Pathology, Microbiology and Immunology, University of California-Davis, One Shields Avenue, 4206 VM 3A, Davis, CA 95616-5270, USA Received 15 April 2008; received in revised form 1 May 2008; accepted 2 May 2008 Available online 2 June 2008 KEYWORDS Quantitative real-time PCR; Cetacean; Cytokine; Immunology; Gene expression; Pacific white-sided dolphin; Beluga whale; Bottlenosed dolphin Summary Real-time quantitation of cytokine mRNA is a routine immunologic technique, especially fitting for use in those species for which monoclonal antibodies are not available. Quantitative gene expression assays were developed to assist in the immunologic assessment of three cetacean species including bottlenosed dolphins, Pacific white-sided dolphins and beluga whales. Nine cytokine genes (IL-2, -4, -10, -12, -13, -18, TNFa , TGFb and IFNg) and Cox-2 were selected for analysis. Most mitogen-induced mononuclear leukocyte responses were similar between the three cetacean species with either up- or down-regulation of cytokine genes. IL-10 expression was highly variable between species. No T H /1T H 2 polarization was evident. Cytokine gene analysis has the potential to identify immune system perturbations induced by environmental insult as well as providing diagnostic tools for characterizing immune responses to environmental antigens and vaccines. & 2008 Elsevier Ltd. All rights reserved. Introduction Interest in cetacean immunology is gaining momentum due to the significant value of these animals in marine parks, naval defense and swim-with-dolphin programs. Efforts to advance immunologic research in these animals are also enhanced by their international visibility as being free- ranging species with significant susceptibility to environ- mental degradation. Cetaceans share many key immunologic components with those previously established in rodents and humans [1]. However, the influence of a marine habitat, and ARTICLE IN PRESS 0145-305X/$ - see front matter & 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.dci.2008.05.001 Abbreviations: C V , coefficient of variation; SI, stimulation index; IL, interleukin; TGF, transforming growth factor; TNF, tumor necrosis factor; IFN, interferon. à Corresponding authors. Tel.: +1 530 752 7187; fax: +1 530 752 3349 (T. Sitt), tel.: +1 530 752 2543; fax: +1 530 752 3349 (J.L. Stott). E-mail addresses: tsitt@ucdavis.edu (T. Sitt), jlstott@ucdavis.edu (J.L. Stott). Developmental and Comparative Immunology (2008) 32, 1253–1259