Dietary 18:3omega3 Influences Immune Function and the Tissue Fatty Acid Response to Antigens and Adjuvant

Alpha-linolenic acid (18:3omega3) has many important physiological functions including being beta-oxidized, serving a precursor to the synthesis of other lipids and it has immunomodulation properties. The objective of the present study was to test the effects of immunization and dietary 18:3omega3 on immune function and the fatty acid profile of immunized pig tissues. Piglets suckled from sows consuming either a control or high 18:3omega3 diet until 14 days old when they were weaned onto a similar diet as the sow and were moved to a segregated nursery for the remainder of the study. At 35 days of age, pigs on both diets (2 x 2 factorial design) received either an injection containing hen eggwhite lysozyme (HEWL), killed Mycobacterium tuberculosis and Freund's complete adjuvant (immunized) or phosphate buffered saline (PBS) (non-immunized) into the neck followed by a booster injection 2 weeks later and induction of delayed-type hypersensitivity (DTH) one week later. Immunization increased (compared to non-immunized) while the high 18:3omega3 diet decreased haptoglobin by 30% compared to pigs consuming the control diet. Immunized pigs had a seven-fold increase in antibodies to HEWL and pigs consuming the high 18:3omega3 diet also had transiently higher levels of serum antibodies. There was a diet by immunization interaction on the DTH reaction such that immunized pigs consuming the high 18:3omega3 had the largest DTH reaction. The neck muscle proximal to the site of injection of immunized pigs had 10-30% lower levels of triglyceride and phospholipid linoleic (18:2omega6) and 18:3omega3 compared to non-immunized pigs. Thus, a high 18:3omega3 intake in pigs modulates immune function and tissue fatty acids in response to immunization.