Variability in cytokine production and cell proliferation by mitogen-activated ovine peripheral blood mononuclear cells: modulation by interleukin (IL)-10 and IL-12 S. Wattegedera a, * , K. Sills a , C.J. Howard b , J.C. Hope b , C.J. McInnes a , G. Entrican a a Moredun Research Institute, International Research Centre, Pentlands Science Park, Bush Loan, Edinburgh, EH26 0PZ, UK b Institute for Animal Health, Compton, Newbury, RG20 7NN, UK Received 7 January 2004; received in revised form 8 June 2004; accepted 14 June 2004 Abstract T-cell reactivity is typically measured by cell proliferation and/or production of cytokines in response to antigenic/mitogenic stimulation. The choice of assays is more limited in ruminants than rodents, and complicated by the variability inherent in outbred populations. We have measured proliferation and production of interferon-gamma (IFN-g) by peripheral blood mononuclear cells (PBMC) from 24 sheep, and compared the responses between sheep, within sheep over several sample points, and also drawn comparisons between the two assays. PBMC derived from different sheep varied by as much as ten-fold in both proliferation and IFN-g production, though not necessarily at the same sample time. Thus, there was a poor correlation between the two assays and also considerable variation in the responses from the same animal at different time points. Both parameters could be modulated by exogenous recombinant ovine interleukin (IL)-10 and IL-12, but we were unable to correlate IFN-g production with endogenous cytokine production in the assays. These data highlight the importance of assay selection for the measurement of immune responsiveness and also demonstrate the variation that can be expected between sheep and over time. # 2004 Elsevier B.V. All rights reserved. Keywords: IFN-g; Ovine; Cytokine modulation; IL-10; IL-12 1. Introduction The identification and measurement of factors that initiate and regulate immune responses is important for our understanding of disease pathogenesis and for the design of effective control strategies. Data gener- ated from murine and human studies indicate that the balance of appropriate T-helper type-1 (Th-1 type) and T-helper type-2 (Th-2 type) cytokines is critical in the www.elsevier.com/locate/vetimm Veterinary Immunology and Immunopathology 102 (2004) 67–76 Abbreviations: CHO, Chinese Hamster ovary cells; CM, cere- bral malaria; ICAM-1, intracellular adhesion molecule-1; LSA, lymphocyte stimulation assay; r, correlation coefficient; Rov, recombinant ovine; SIs, stimulation indices; Th-1 type, T-helper type-1; Th-2 type, T-helper type-2; UTF, untransfected. * Corresponding author. Tel.: +44 131 445 5111; fax: +44 131 445 6235. E-mail address: sean.wattegedera@mri.sari.ac.uk (S. Wattegedera). 0165-2427/$ – see front matter # 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.vetimm.2004.06.006