Beta-carotene-induced enhancement of natural killer cell activity in elderly men: an investigation of the role of cytokines.
We showed previously that natural killer (NK) cell activity is significantly greater in elderly men supplemented with beta-carotene than in those taking placebo. In an attempt to determine the mechanism of beta-carotene's effect, we analyzed the production of NK cell-enhancing cytokines (interferon alpha, interferon gamma, and interleukin 12). Boston-area participants in the Physicians' Health Study (men aged 65-88 y; mean age, 73 y) who had been supplemented with beta-carotene (50 mg on alternate days) for an average of 12 y were enrolled in a randomized, placebo-controlled, double-blind study. Elderly subjects taking beta-carotene supplements had significantly greater plasma beta-carotene concentrations than those taking placebo. Beta-carotene-supplemented elderly men had significantly greater NK cell activity than did elderly men receiving placebo. Percentages of NK cells (CD16+CD56+) were not significantly different between the beta-carotene and placebo groups. Production of interleukin 12, interferon alpha, or concanavalin A-stimulated interferon gamma by cultured peripheral blood mononuclear cells was not significantly different between beta-carotene-supplemented elderly and those taking placebo. Our results indicate that beta-carotene-induced enhancement of NK cell activity is not mediated by changes in percentages of CD16+CD56+ NK cells nor through up-regulation of interleukin 12 or interferon alpha.
Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111, USA.
M S
MS
Santos
J M
JM
Gaziano
L S
LS
Leka
A A
AA
Beharka
C H
CH
Hennekens
S N
SN
Meydani
D000368:Aged; D000375:Aging / Q000276:immunology*; D016207:Cytokines / Q000096:biosynthesis*; D019587:Dietary Supplements; D004311:Double-Blind Method; D006801:Humans; D016898:Interferon-alpha / Q000096:biosynthesis; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000276:immunology*; D008297:Male; D010820:Physicians; D010919:Placebos; D019207:beta Carotene / Q000008:administration & dosage*
D016207:Cytokines; D016898:Interferon-alpha; D010919:Placebos; D019207:beta Carotene; D018664:Interleukin-12; D007371:Interferon-gamma