Satoru Moriguchi

β-carotene supplementation enhances lymphocyte proliferation with mitogens in human peripheral blood lymphocytes

Abstract This study was performed to determine the effect of β-carotene supplementation on the proliferation of human peripheral blood lymphocytes (PBL) with T-cell mitogens such as phytohemagglutinin (PHA) and concanavalin A (Con A). Subjects were healthy male university students (19 to 22 years old) without smoking habit. After the subjects were divided into two groups; control (n=7) and β-carotene supplemented (n=8) groups, they received lactose (30 mg/day) and β-carotene (30 mg/day) for 30 days, respectively. Their peripheral blood lymphocytes (PBL) were separated by Percoll-density gradient centrifugation and used for immunological assays. The number of PBL from β-carotene supplemented group was not significantly different from control group. Although there was also no significant difference in natural killer cell (NK) activity between both groups (Control; 33.4 ± 8.2%, β-carotene; 32.5 ± 7.7%), proliferation of PBL with PHA or ConA was 1.4 to 1.9 fold higher in β-carotene supplemented group compared to that of control group. However, the proportions of T cell subsets in PBL and interleukin 2 (IL2) activity in the supernatant of PBL cultures stimulated in vitro with Con A were not significant differences between control and β-carotene supplemented groups. In particular, IL2 activity was lower in β-carotene supplemented subjects compared to that of control subjects. These results suggest that the enhancement of PBL proliferation following β-carotene supplementation is not due to the qualitative change in T cell subsets of PBL and the increase in IL2 production as T cell growth factor but due to the enhancement in the responsiveness of PBL to mitogen.

Obesity is a risk factor for deteriorating cellular immune functions decreased with aging

Abstract This study was performed to determine the effect of obesity on cellular immune functions in the aged. Subjects were healthy men (n=111) and women (n=126) living in Tokushima prefecture and randomly sampled (range 30–69 years old). Although natural killer cell (NK) activity was almost similar in both men and women at all ages, proliferation of peripheral blood lymphocytes (PBL) with phytohemagglutinin (PHA) and concanavalin A (ConA) showed a downward trend with advancing age. The average of body mass index (BMI) as an index of obesity at each age was not significantly different in both men and women. Blood glucose levels significantly increased with advancing age in both men and women. Both NK activity and proliferation with PHA of PBL were significantly higher in both men and women with high BMI (> 30) compared to the subjects with normal BMI (20–25), whereas at 60–69 years old they were significantly decreased in high BMI group compared to those of normal BMI group. These results suggest that obesity aggravates cellular immune functions decreased with aging.

Effect of alanylglutamine-enriched infusion on tumor growth and cellular immune function in rats

SummaryThe effects of total parenteral nutrition containing alanylglutamine (Ala-Gln) on tumor growth and cellular immune response were examined in rats inoculated Yoshida sarcoma cells subcutaneously. Rats given Ala-Gln-enriched solution intravenously showed a positive nitrogen balance and the increased function of alveolar macrophages. Studies on in vitro effect of Ala-Gln on immune cells in control rats showed a significant increase in phagocytic activity of alveolar macrophages and in blastogenic response of splenocytes, respectively. In vitro experiment of Gln or Ala-Gln addition to culture medium showed a remarkable enhancement of incorporation of3H-thymidine into Yoshida sarcoma cells, but in vivo administration of Ala-Gln containing solution did not accelerate the growth of the same tumor as measured by changes in the weight and volume. These results suggest that Ala-Gln infusion does not stimulate tumor growth due to maintenance of some immune-enhancing effect by Gln liberated from Ala-Gln in tumor-bearing hosts.

Vitamin E enhances T cell differentiation through increased epithelial cell function in rat thymus

This study was designed to elucidate the mechanism on increased T cell differentiation in thymus following vitamin E supplementation and discussed on the changes of epithelial cell (TEC) and macrophage functions in thymus following vitamin E supplementation. Thymic epithelial cells isolated by panning method from thymocytes of rats fed the high vitamin E (500 IU α-tocopherol nicotinate/kg) diet for 7 weeks increased the proportion of CD4+CD8- T cells in thymocytes. In addition, when thymic epithelial cell line IT45-R1 was pretreated with vitamin E for 24 h and then incubated with immature T cells for 48 h, they also enhanced the proportion of CD4+CD8-T cells in thymocytes. On the contrary, the supernatant of IT45-R1 treated in vitro with vitamin E for 24 h did not have any effect on the proportions of T cell subsets in thymocytes. Furthermore, in vitro treatment with vitamin E significantly enhanced the binding capacity of TEC to immature T cells. The expression of adhesion molecule, ICAM-1, on the membrane of TEC was also greatly increased by high vitamin E diet. However, in vitro incubation with macrophages isolated from rats fed the regular or high vitamin E diet did not induce a significant difference in the changes of T cell subsets in immature T cells. These results suggest that vitamin E enhances T cell differentiation through the increase of not macrophage but TEC function in thymus, which is associated with the increased binding capacity of TEC to immature T cells via increased expression of ICAM-1.

Functional changes in human lymphocytes and monocytes after in vitro incubation with arginine

Abstract Human lymphocytes and monocytes obtained from healthy nonsmoking volunteers, were activated by in vitro incubation with excess arginine. Natural killer cell (NK) activity was increased three-fold after in vitro incubation with 64×10 2 μg/ml of arginine and 4×10 2 μg/ml of arginine induced 1.5 fold increase of human monocytes-mediated(HM) cytotoxicity. Production of tumor cytotoxic factor (TCF) from human monocytes significantly increased after in vitro incubation with arginine (8×10 2 and 32×10 2 μg/ml) for 24 hr. At high concentrations of arginine, in vitro growth of tumor cells was evidently suppressed. These results suggest that arginine action against tumor cells is due to, in part, not only via the enhancement of host immune functions (NK activity and HM cytotoxicity) but also direct effect to tumor cells.

Vitamin E prevents the decrease of cellular immune function with aging in spontaneously hypertensive rats

This study was performed to investigate the mechanism of vitamin E (VE) induced restoration of cellular immune functions decreased with aging in spontaneously hypertensive rats (SHR). Both Wistar Kyoto rats (WKY) as control rats and SHR, 3 weeks old, were fed a diet supplemented with 50 or 585 mg VE/kg diet for 37 weeks. The changes in proportions of thymocyte subsets with aging were not significantly different between WKY and SHR. On the contrary, the expressions of both CD4 and CD8 antigens in CD4+CD8+ thymocytes were significantly reduced in SHR compared to those of WKY at the same age, which was significantly improved by taking the high VE diet at 6 or 12 weeks old. Furthermore, the production of interleukin 2 (IL2) from thymocytes was also decreased in SHR compared to WKY, which was improved by both high VE diet and in vitro treatment with indomethacin, inhibitor of PGE2 synthesis. In addition, natural thymocytotoxic autoantibody (NTA) titer in serum of SHR was also increased with aging and this increase was suppressed by feeding high VE diet until 12 weeks old after which it showed the same trend as that of SHR fed the control diet. These results suggest that VE induces the prevention in cellular immune functions decreased with aging in SHR, which is due to the increased production of IL2 and the decreased production of NTA from thymocytes following VE supplementation.

Effect of vitamin E supplementation on cellular immune functions decreased with aging in spontaneously hypertensive rats

Abstract This study was performed to determine the effect of vitamin E supplementation on cellular immune functions decreased with aging in spontaneously hypertensive rats(SHR). Both Wistar Kyoto rats(WKY) as control rats and SHR, 6 weeks old, were fed a diet supplemented with 50 or 585 mg vitamin E/kg diet for 2 or 6 weeks. SHR fed the control diet were apparently in the vitamin E deficient status. In those SHR, mitogenesis and natural killer cell(NK) activity of splenocytes remarkably declined with aging while alveolar macrophage(AM) showed a higher phagocytic activity compared to that of WKY. Furthermore, high vitamin E diet could restore proliferations of thymocytes and splenocytes with phytohemagglutinin(PHA) and concanavalin A(Con A) in SHR. However, the effect of dietary vitamin E on T cell responses was strongly shown in WKY rather than SHR and in 2-week rather than those in 6-week. NK activity of splenocytes in SHR remained the decreased state even after 6 weeks-feeding of high vitamin E diet. These results suggest that vitamin E supplementation may restore, in part, cellular immune functions decreased with aging in SHR and the effect of high vitamin E diet may be limited in T cell responses.

In vitro effect of retinol and 13-cis retinoic acid on cytotoxicity of human monocytes

Abstract Human monocytes (HM) obtained from healthy nonsmoking donors were rendered tumoricidal activity following 24 hr-incubation in vitro with retinol (RL) or 13-cis retinoic acid(13cRA). HM treated with medium only did not kill tumor cells. Maximum tumoricidal activity of HM, as measured by lysis of 125 I-iododeoxyuridine labeled C83-2C human melanoma cells, was obtained after incubation with 10 −8 M of RL or 10 −6 M of 13cRA for 24 hr. Tumoricidal activity rendered by incubation in vitro with RL or 13cRA cell to half of maximum activity following further incubation in vitro with medium only for 24 hr. Pretreatment of HM with 10 −8 M of RL for 0 to 24 hr did not interfere the activation of macrophage activating factor (MAF) against HM and did induce the enhancement of tumoricidal activity of HM rather than that of MAF only. We conclude that RL and 13cRA could induce HM to become tumoricidal. This may help to explain greater cancer prevention of vitamin A and its derivatives.

EFFECT OF DIETARY PROTEIN LEVELS ON IMMUNE FUNCTION OF EXERCISED RATS

Abstract The purpose of this study was to determine the effects of different levels of dietary protein on cellular immune function of exercised rats. At 5 weeks old of age, male Fisher rats were fed diets composed of 5, 20, 40 and 60% casein levels and subjected daily to voluntary exercise on a wheel mill. At the end of an 8 week-training period, splenocytes and alveolar macrophages (AM) were isolated from exercised rats and from sedentary controls. Splenocyte proliferation induced by phytohemagglutinin (PHA), interleukin-1 (IL-1) production and phagocytosis of AM were measured, separately. It was found that exercise resulted in increases in IL-1 production and phagocytosis of AM in 20 or 40 % casein group compared with 5% casein group. However, in the 60% casein group, phagocytosis of AM decreased in both control and exercised rats. The above results suggest that the diets containing adequate level (20–40%) of protein are the most suitable for increasing cellular immunity in case of taking voluntary exercise.

In vitro activation of tumoricidal properties of human monocytes by β-carotene encapsulated in liposomes

Abstract The present work was carried out to study the effect of β-carotene (β) or β-carotene encapsulated in liposomes (L+β) on tumoricidal activity of human monocytes (HM). Tumoricidal activity of HM was measured by using 125 I-iododeoxyuridine labeled C83-2C human melanoma cells. Maximum tumoricidal activity of HM was obtained after in vitro incubation with 10 −7 M of β or L+β. And L+β induced higher tumoricidal activity of HM than that of β. Higher tumoricidal activity of HM (20.4%) was induced by in vitro incubation with L+β for 3 hr and it reached a maximum at 24 hr-incubation. Tumoricidal activity rendered by incubation in vitro with L+β gradually decreased and fell to half of maximum activity following further incubation with medium only for 72 hr. These results suggest that β induces HM to become tumoricidal and L+β may further enhance the effect of β on tumoricidal activity of HM.