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Acute inflammation was induced in pigs using a single subcutaneous turpentine injection. The acute phase serum protein response was analyzed using crossed immunoelectrophoresis and immunodiffusion. The concentration of C reactive protein and haptoglobin increases 5-7 times 48 h after the injection, whereas the concentration of an alpha 2-globulin, named pig major acute phase protein (pig-MAP), increases at least 15-fold. A molecular mass of 115 kDa for pig-MAP was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein did not crossreact with antisera to human hemopexin, ceruloplasmin, H-kininogen and complement factor C3. Albumin and alpha-lipoprotein were negative acute phase proteins because their concentration significantly decreased during inflammation. Finally, the concentration of alpha 1-acid glycoprotein, fetuin, alpha 1-protease inhibitor, transferrin and alpha 2-macroglobulins, as well as total proteins, did not change significantly during inflammation.

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The acute-phase expression of pig MAP (major acute-phase protein)/ITIH4 (inter-a-trypsin inhibitor heavy chain 4) and haptoglobin were analysed in primary cultures of isolated pig hepatocytes in response to recombinant human (rh) cytokines: tumor necrosis factor-a (TNF-a), interleukin-1 (IL-1), interleukin-6 (IL-6), as well as to bacterial lipopolysaccharide (LPS). Analysis of pig MAP/ITIH4 and haptoglobin mRNAs was carried out by RT-PCR amplification. Secreted proteins from the cytokine-treated hepatocytes were quantified by immunochemical techniques. Time-course and dose±response experiments show that pig MAP/ITIH4 and haptoglobin belong to the type II acute-phase proteins, as they are specifically induced by rhIL-6 and not by rhTNF-a or rhIL-1. Stimulation of cultured pig hepatocytes with rhIL-6 for 48 h at doses of 1000 U´mL 21 showed a fourfold to fivefold increase in pig MAP/ITIH4 concentration in the medium, while the concentration of haptoglobin only increased twofold. A similar increase in the concentration of pig MAP/ITIH4 was also observed in media of LPS-treated hepatocytes with the simultaneous generation of IL-6 by the Kupfer cells present in the cultures. Albumin secretion decreased after stimulation with doses of 100 or 1000 U´mL 21 rhTNF-a, rhIL-1 or rhIL-6. Therefore, it can be concluded that pig MAP/ITIH4 behaves as a major acutephase protein produced by porcine hepatocytes under the effect of inflammatory cytokines.Keywords: acute-phase proteins; cytokines; hepatocytes; inter-a-trypsin inhibitor (IaI); ITIH4.The acute-phase response of an organism to infection, tissue injury and inflammation consists, apart from local reactions, of a systemic response characterized by fever, leukocytosis, secretion of glucocorticoids, activation of complement and clotting cascades, and a dramatic change in the concentration of some plasma proteins denoted acute-phase proteins [1±3]. Activated macrophages or blood monocytes release inflammation-related cytokines, such as tumor necrosis factor (TNF), interleukin-1 (IL-1) and interleukin-6 (IL-6), which initiate the acute-phase response [4]. Inflammation-related cytokines act as primary stimulators of acute-phase proteins gene expression in the liver, which is also modulated by glucocorticoids and growth factors. They are grouped in two major categories: (a) gp130 signalling cytokines (IL-6-type cytokines): IL-6, IL-11, leukaemia inhibitory factor, oncostatin M, ciliary neurotrophic factor and cardiotropin; and (b) IL-1-type cytokines, IL-1a, IL-1b, and TNF (a and b) [3,4].Acute-phase proteins have been studied extensively in humans and in the rat. Several studies in vivo and in vitro have been performed to analyse the response of acute-phase proteins to cytokine stimulation and IL-6 has been recognized as the principal regulator of most acute-phase protein genes in both species [5].Not much is known about the acute-phase protein response in domestic animals. Haptoglobin, C-reactive protein and serum amyloid A have been reported to be acute-phase proteins in pig...