Delayed hypersensitivity response and vitamin D deficiency.

The relationship between delayed hypersensitivity and serum levels of 25-hydroxyvitamin D were examined in sixty-three elderly people. After intracutaneous injection of five recall antigens (Candida, mumps, PPD, tricophyton and varidase) nineteen subjects showed no response (anergy), seven showed only a weak reaction (relative anergy), and thirty-seven a normal reaction. In the anergic group mean serum level of 25-hydroxyvitamin D was significantly lower than in the group with normal immunoreactivity. Five subjects with anergy and serum 25-hydroxyvitamin D below 20 nmol/l were treated with oral vitamin D or UV irradiation for two to three months, after which both the serum 25-hydroxyvitamin D levels and the delayed hypersensitivity were normalized. In a non-treated group anergy persisted in seven out of nine patients in a second skin test. We conclude that anergy in the delayed hypersensitivity skin test in humans may in some cases be due to vitamin D deficiency.