Interferon responsiveness of natural killer cells in type I human diabetes

Abnormally low circulating numbers and function of NK cells are associated with new onset type I diabetes. Since alpha interferon is a stimulator of NK function, enriched T and non-T lymphocytes were incubated with 0, 100 and 1,000 units/ml of recombinant alpha interferon (rIFN alpha) and natural killing against K562 and pancreatic islet cell targets was measured. The killing of K562 (1:20 target:effector ratio) cells by non-T cells incubated with 0, 100 and 1,000 units/ml of rIFN alpha in patients was decreased to 27% (p less than 0.014 vs control), 34% (p less than 0.001) and 39% (p less than 0.003) when compared to killing by normal control non-T cells (48%, 74% and 58% respectively). T cell mediated killing of K562 cells in patients was decreased to 3.9% (p less than 0.03), 5.3% and 6.6% (p less than 0.003) when compared to that of controls (8.7%, 10-8% and 22.6% respectively). Non-T cell mediated killing of islet cells (1:20 target:effector ratio) following treatment of effector cells with 0, 100 and 1,000 units/ml of rIFN alpha in patients was 19%, 27%, and 26% which was comparable to control subjects killing of 31%, 18% and 37% respectively. Similar data were obtained using T-cells as effectors. These data indicate that in new onset type I diabetes; (a) NK cell functional activity is diminished in both T and non-T lymphocyte subpopulations and (b) NK activity is suboptimally enhanced with rIFN alpha.