Immunomodulating actions of carotenoids: Enhancement of in vivo and in vitro antibody production to T‐dependent antigens

Abstract

Previously, we demonstrated an enhancement of in vitro antibody (Ab) production in response to T‐dependent antigens (TD‐Ag) by astaxanthin, a carotenoid without vitamin A activity. The effects of β‐carotene, a carotenoid with vitamin A activity, and lutein, another carotenoid without vitamin A activity, on in vitro Ab production were examined with spleen cells from young and old B6 mice. In addition, the in vivo effects of lutein, astaxanthin, and β‐carotene on Ab production were studied in young and old B6 mice.

Lutein, but not β‐carotene, enhanced in vitro Ab production in response to TD‐Ags. The depletion of T‐helper cells prevented the enhancement of Ab production by lutein and astaxanthin. In vivo Ab production in response to TD‐Ag was significantly enhanced by lutein, astaxanthin, and β‐carotene. The numbers of immunoglobulin M‐ and G‐secreting cells also increased in vivo with the administration of these carotenoids when mice were primed with TD‐Ags. Antibody production in response to TD‐Ags in vivo and in vitro was significantly lower in old than in young B6 mice. Astaxanthin supplements partially restored decreased in vivo Ab production in response to TD‐Ags in old B6 mice. Lutein and β‐carotene also enhanced in vivo Ab production in response to TD‐Ags in old B6 mice, although to a lesser extent than did astaxanthin. However, none of the carotenoids had an effect on in vivo or in vitro Ab production in response to T‐independent antigen.

These results indicate significant immunomodulating actions of carotenoids for humoral immune responses to TD‐Ags and suggest that carotenoid supplementation may be beneficial in restoring humoral immune responses in older animals.