Complex effects of vitamin E and vitamin C supplementation on in vitro neonatal mononuclear cell responses to allergens

Abstract

Low maternal dietary vitamin E (but not vitamin C) intake during pregnancy has been associated with increased in vitro cord blood mononuclear cell (CBMC) proliferative responses, childhood wheezing and asthma. We investigated whether these associations reflect direct effects of vitamin E by investigating the effects of supplementing CBMC cultures with physiological concentrations of vitamin E. CBMC from seventy neonates were cultured supplemented with either nothing, α-tocopherol or ascorbic acid. Proliferative, IFN-γ, IL-4, IL-10 and TGF-β responses were measured. In general, vitamin E supplementation was associated with a trend for reduced proliferative responses after stimulation with antigens and house dust mite, and with increased proliferation after stimulation with timothy grass allergen. There was a trend for CBMC cultures to exhibit decreased secretion of IFN-γ, IL-10 and IL-4. Supplementation with vitamin C had no effect on CBMC proliferation, but increased IFN-γ and IL-4 production, and decreased IL-10 production. In conclusion, in vitro vitamin E and C supplementation of CBMC modifies neonatal immune function, but not in a manner predicted by observational epidemiological studies. The observed associations between vitamin E and childhood respiratory disease are complex, and the nature and form of nutritional intervention need to be carefully considered before inclusion in trials.

Figure 1

Responses of 70 cord blood mononuclear cell (CBMC) samples to control stimuli and allergens, with or without supplementation with vitamin E. Responses are expressed as stimulation index. Bars represent mean stimulation indices for each set of culture conditions. Significant p values for differences in responses between paired samples in cultures with or without vitamin E supplementation are shown on the relevant panels.

Figure 2

Responses of 18 PBMC samples to control stimuli and allergens, with or without supplementation with vitamin E. Reponses are expressed as stimulation index. Bars represent mean stimulation indices for each set of culture conditions. Significant p values for differences in responses between paired samples in cultures with or without vitamin E supplementation are shown on the relevant panels.

Figure 3

Responses of 51 CBMC samples to control stimuli and allergens, with or without supplementation with vitamin C. Reponses are expressed as stimulation index. Bars represent mean stimulation indices for each set of culture conditions. Significant p values for differences in responses between paired samples in cultures with or without vitamin C supplementation are shown on the relevant panels.

Figure 4

Responses of 18 PBMC samples to control stimuli and allergens, with or without supplementation with vitamin C. Reponses are expressed as stimulation index. Bars represent mean stimulation indices for each set of culture conditions. Significant p values for differences in responses between paired samples in cultures with or without vitamin C supplementation are shown on the relevant panels.

Figure 5

Summary of differential effects of vitamin E or C supplementation on CBMC or PBMC responses to allergen. Proliferation and secretion of IFN-γ, IL-10, IL-4 and TGF-β are expressed as the mean percentage change between paired unsupplemented and supplemented cultures. Significant p values for differences in responses between paired samples in cultures with or without vitamin supplementation are shown on the relevant panels.