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Modulation of the Immune Response by Conjugated Linoleic Acid: Clinical Development from an Industry Perspective

Marianne O'Shea(1), Josep Bassaganya-Riera(2), Raquel Hontecillas(2), and Inge Mohede(3).
(1)Loders Croklaan, Lipid Nutrition, Channahon, Illinois, USA.
(2)Nutritional Immunology & Molecular Nutrition Laboratory, Department of Human Nutrition, Foods & Exercise, Virginia Polytechnic Institute and State University.
(3)Loders Croklaan, Lipid Nutrition, Wormerveer, The Netherlands.


Results from in vitro experiments in lymphocytes and animal studies indicate that conjugated linoleic acid (CLA) enhances immune function. We have examined the effects of two CLA preparations (i.e., 50:50 and 80:20 of c9,t11: t10,c12) on antigen-specific responses in humans and using a pig model of immunosuppressive viral disease.
The human immunization study reports the effects of CLA supplementation (1.7 g active isomers/day for 12 weeks) on humoral and cell-mediated immune responses. Specifically, Hepatitis B virus (HBv) vaccination was used to investigate the modulation of antigen-specific humoral immune responses by CLA. The seroprotection rate (SPR, i.e. the number of subjects with anti-HBv antibody concentrations >10 IU/L compared to the number of subjects with titers <10 IU/L) was significantly higher (P=0.05) for the 50:50 group compared to control or the 80:20 group. Our pig model of immunosuppressive viral disease consisted of an experimental vaccination and challenge with type-2 porcine circovirus (PCV2). Using this pig model we examined the regulation of antigen-specific proliferation of lymphocytes, lymphoid depletion (due to the infection) and immune suppression by CLA when compared with soybean oil (1% diet). Following 42 days of dietary supplementation, pigs (n=32) were immunized and monitored until day 63. Proliferation of lymphocytes in response to ex vivo stimulation with a recombinant capsid protein open reading frame 2 (ORF2) of PCV2 was assessed by PKH67 and blastogenesis assays. Serum samples were assayed for the presence of PCV2-specific antibodies using an indirect enzyme-linked immunosorbent assay and IFA. On days 49, 56, and 63, pigs fed CLA-supplemented diets had significantly greater cellular immune responses as reflected in the increase of CD8+ than the littermates fed isocaloric control diets (P < 0.05, 0.04, and 0.02, respectively).
The findings from human and animal studies are suggestive that the CLA-induced enhancement of humoral and cellular responses could be maximized in immunocompromised individuals.

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