We know it for ages (1985) that 1,25-Dihydroxyvitamin D3 suppresses human T helper cells by blocking interleukin 2 (IL 2) production. The immune effects were our main argument 2001 against oral vitamin D supplementation of newborns as it may induce later allergy . It is now funny to find now a clinical trial that tests low-dose interleukin-2 in birch pollen allergy.