We studied the influence of ascorbate (vitamin C) on peripheral blood
mononuclear cells (PBMC) of pigs with hereditary deficiency in ascorba
te synthesis. Groups of animals were depleted of, or supplemented with
dietary ascorbate for up to 5 weeks. B lymphocytes and T lymphocyte s
ubsets differed in the two experimental groups only marginally and tra
nsiently as determined by analysis of cell surface markers. The prolif
erative response of PBMC to B and T lymphocyte mitogens was lower in d
epleted as compared to supplemented animals. Interleukin (IL)-2 and IL
-6 were determined by bioassays and were secreted within few hours aft
er mitogenic activation of PBMC which contained normal physiological c
oncentrations of ascorbate. IL-2 production peaked at about 24 h of in
vitro culture after Con A activation, but it lasted for 2-3 days afte
r PWM activation. The production of IL-2 and IL-6 were compared during
systemic depletion and supplementation with ascorbate. Depleted PBMC
produced IL-2 which accumulated in cultures instead of being rapidly c
onsumed by n-2 dependent cell growth. This suggests that cellular asco
rbate influences the production of n-2. Secretion of IL-6 by mitogen a
ctivated PBMC was also affected by prolonged dietary ascorbate depleti
on. The results suggest that ascorbate levels exert an early effect on
immune homeostasis via reactive oxygen intermediates (ROI) -dependent
expression of interleukin genes, since the transcription factor NF-ka
ppa B is sensitive to ROI and regulates the expression of interleukin
genes. (C) 1998 Elsevier Science B.V. All rights reserved.