Moreover, astaxanthin potentiated LPS-induced cell proliferationex vivo(Figure 2D), but was not effective in Con A-stimulated proliferation (Figure 2E). == Figure 2 . production. In anex vivoexperiment, oral administration of astaxanthin (0. 28, 1 . 4 and 7 mg/kg/day) for 14 days did not cause alterations in the body or spleen weights of mice and also was not toxic to lymphocyte cells derived from the mice. NADP Moreover, treatment with astaxanthin significantly increased LPS-induced lymphocyte proliferationex vivobut not Con A-stimulated lymphocyte proliferationex vivo. Enzyme linked immunosorbent assay (ELISA) analysis revealed that administration of astaxanthin significantly enhanced INF- production in response to both LPS and Con A stimulation, whereas IL-2 production increased only in response to Con A stimulation. Also, astaxanthin treatment alone significantly increased IL-2 production in lymphocytes derived from mice, but did not significantly change production of INF-. These findings suggest that astaxanthin modulates lymphocytic immune responsesin vitro, and that it partly exerts itsex vivoimmunomodulatory effects by increasing INF- and IL-2 production without inducing cytotoxicity. Keywords: astaxanthin, LPS, Con A, mice, lymphocytes, INF-, IL-2, immunomodulation == 1 . Introduction == It is important to understand the immunomodulatory properties of herbal medicines in order to provide new insights into immune function and to uncover possible avenues for immunotherapy. Immunopharmacology NADP aims to search for immunomodulators. Increasing evidence suggests that plant-based natural substances can serve as immunomodulators to control the outcome of certain immune responses. Herbal preparations have been shown to alter immune functions and to exert a wide range of immunomodulatory effects. Since plant-derived immunomodulatory substances increase immune responsiveness by triggering competent cells of the immune system, studies of medicinal plants are needed to substantiate claims that they possess prophylactic and therapeutic properties that are useful in the clinical setting [1]. In addition to medical properties, physiological interferon (IFN) has been reported to increase following intraduodenal administration of alimentary lectins [2]. Moreover, a study found that splenocytes of mice fed with a mixture of fish oil and high concentrations of proteins/lectins increased levels of interleukins (IL-2 and 4), and IFN- in response to concanavalin A (Con A) [3]. Recently, Requenaet al.[4] also reported that oral administration of -casein glycopeptide, an active component of milk, upregulates the expression of tumor necrosis factor- mRNA in Con A-stimulated splenocytes. Thus, studying the cytokine-modulating effect of medicinal herbs or foods is a useful approach to elucidating their immunopharmacological functions, mechanisms of oral immune responses to allergies, and immunotolerance. Astaxanthin, a xanthophyll carotenoid, has been found in various microorganisms and marine animals [5]. A previous study showed that astaxanthin scavenged free radicals more effectively than did -carotene, and inhibited lipid peroxidation more vigorously than did canthaxanthin, -carotene NADP or zeaxanthin [6]. Astaxanthin has been approved by the United States Food and Drug Administration (USFDA) for use as a food colorant in animal and fish feed [7]. Also, it is used as a source of pigment in the feed for salmon, trout and shrimp [5]. The consumption of astaxanthin is reported to prevent or reduce the risk of occurrence of different complaints in humans and animals [8, 9]. Previous studies have shown that natural carotenoids play major roles in regulating immunity and disease etiology [10]. Dietary astaxanthin is reported to stimulate mitogen-induced lymphocyte proliferation, increase natural killer cell cytotoxicity and the delayed-type hypersensitivity response, and increase the number of total T and B cells in the peripheral blood [11]. Parket al.[12] showed that astaxanthin is absorbed after oral administration in domestic cats and it is subsequently utilized by COG7 blood leukocyte subcellular organelles, mostly by the mitochondria. Hitherto, research has tended to focus on the biological effects of astaxanthin, and there are no detailed reports on its immunomodulatory effects with possible molecular mechanisms. In this study, we examined the effects of astaxanthin on Con A- and lipopolysaccharide (LPS)-induced IL-2 and IFN- production in primary cultured lymphocyte cellsin vitroandex vivo. == 2 . Results and Discussion == == 2 . 1 . Results == == 2 . 1 . 1 . Astaxanthin for Cell Viability and Lipopolysaccharide (LPS) and Concanavalin A (Con A) Induced Lymphocyte Proliferation == Cell viability and proliferation of lymphocytes was measured by conducting a 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. As shown.