Natural Killer (NK) cell activity was examined in a 16-month-old Japanese boy with Shwachman syndrome associated with severe vitamin E deficiency. As evaluated by 51Cr-release assay from K562 cells, NK cell activity was constantly decreased. After 8 weeks of oral alpha-tocopherol (alpha-Toc) supplementation (100 mg/day), NK cell activity had normalised. When alpha-Toc supplementation was interrupted for 16 weeks. NK cell activity again decreased. Flow cytometry of peripheral lymphocytes revealed a lowered number of CD16+ CD 56- fraction, which has the most potent NK cell activity. Single cell-in-agarose assay, to investigate the binding and cytolytic activity of NK cell at the single cell level, revealed that the number of NK cells which bind to K562 cell was decreased, but that the cytolytic activity of the individual binding cell was relatively unaffected. A second supplementation of alpha-Toc for 8 weeks successfully restored NK cell activity, the number of cells expressing NK cell markers and the number of K562-binding cells as compared to the age-matched normal range.
Conclusion: These results indicate that severe vitamin E deficiency caused impaired NK cell activity due to a decrease in the number of CD16+ CD56- NK cells and that this abnormality is reversible with alpha-Toc supplementation.