Astaxanthin is a potent antioxidant carotenoid and may play a role in modulating immune
response in cats. Blood was taken from female domestic shorthair cats (8–9 mo old;
3.2
±
0.04 kg body weight) fed 0, 1, 5 or 10 mg astaxanthin daily for 12 wk to assess peripheral
blood mononuclear cell (PBMC) proliferation response, leukocyte subpopulations,
natural killer (NK) cell cytotoxic activity, and plasma IgG and IgM concentration. Cutaneous
delayed-type hypersensitivity (DTH) response against concanavalin A and an attenuated
polyvalent vaccine was assessed on wk 8 (prior to vaccination) and 12 (post-vaccination).
There was a dose-related increase in plasma astaxanthin concentrations, with maximum
concentrations observed on wk 12. Dietary astaxanthin enhanced DTH response to both
the specific (vaccine) and nonspecific (concanavalin A) antigens. In addition, cats fed astaxanthin
had heightened PBMC proliferation and NK cell cytotoxic activity. The population of
CD3+ total T and CD4+ T helper cells were also higher in astaxanthin-fed cats; however, no
treatment difference was found with the CD8+ T cytotoxic and MHC II+ activated lymphocyte
cell populations. Dietary astaxanthin increased concentrations of plasma IgG and IgM.
Therefore, dietary astaxanthin heightened cell-mediated and humoral immune responses
in cats.