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.
