Cold-pressed flaxseed oil reverses age-associated depression in a primary cell-mediated adaptive immune response in the mouse.

The objective of this investigation was to determine the influence of flaxseed oil on responses representative of primary humoral and cell-mediated adaptive immune competence in immunosenescent mice. Male and female C57BL/6J mice, 85 weeks old, were randomized between two complete purified diets differing only in oil source (cold-pressed safflower or flaxseed). After 8 weeks, humoral competence was assessed in six mice per group as the serum haemagglutinin titre to sheep red blood cells (SRBC) and cell-mediated competence was assessed, in an additional six mice per group, as the delayed hypersensitivity response to SRBC. A zero-time control group (88 weeks old) and a young adult positive control group (12 weeks old) were each tested similarly (six per immune response), revealing age-related depression in both antibody and cell-mediated competence at 88 weeks of age. After the 8-week experimental period, the antibody response of the two test groups of geriatric mice remained below the young adult level (P=0.04) and the cell-mediated response of the safflower oil group also continued to exhibit age-related depression (20 % of young adult level, P=0.0002). By contrast, the anti-SRBC delayed hypersensitivity response of the flaxseed group no longer differed from the response of the young adults but exceeded that of the safflower and zero-time control senescent groups (P=0.0002). Depression in primary cell-mediated competence, the most outstanding aspect of immunosenescence, can be addressed by means of a dietary source of 18 : 3n-3 without longer-chain PUFA.

A comparison of the capacity of six cold-pressed plant oils to support development of acquired immune competence in the weanling mouse: superiority of low-linoleic-acid oils.

The objective of this investigation was to compare, at several levels of intake, the capacity of diverse cold-pressed plant oils to support development of acquired immune competence assessed in vivo in the weanling mouse. Safflower, maize, soyabean, rapeseed, flaxseed and olive oils were selected to represent widely differing 18 : 1n-9, 18 : 2n-6 and 18 : 3n-3 contents, and each oil was fed at three dietary levels (40, 80 and 160 g/kg) as the exclusive source of fat. C57BL/6J mice, ten males and ten females, had free access to each diet for 28 d beginning at 19 d of age. The primary serum haemagglutinin response to sheep red blood cells and the primary cutaneous delayed hypersensitivity response to dinitrochlorobenzene were used to assess humoral and cell-mediated competence respectively, on day 28. A zero-time control group, assessed immunologically at 19 d of age, was also included (n 32). Independently of dietary oil level, flaxseed, rapeseed, olive and soyabean oils supported development of a more vigorous antibody response than safflower (a useful point of reference, being rich in 18 : 2n-6 but low in 18 : 1n-9 and 18 : 3n-3), whereas only flaxseed oil supported development of cell-mediated responsiveness exceeding that of safflower-fed mice. Independently of oil type, development of both immunological indices correlated negatively with intake of 18 : 2n-6, and development of humoral competence varied inversely with dietary oil level. A low content of 18 : 2n-6, perhaps less than 20 g/100 g fatty acids, appears important to the capacity of a plant oil to support development of acquired immune competence in the young.