The effect of interleukin-12 and interleukin-15 on CD69 expression of T-lymphocytes and natural killer cells from umbilical cord blood.

We investigated the effect of two immunoregulatory cytokines interleukin-12 (IL-12) and IL-15, alone or in combination, on CD69 expression of mononuclear cells (MNCs) obtained from umbilical cord blood (CB) and adult peripheral blood (APB). We established that (1) CD3/69, but not CD16/69, expression on CB MNCs could be increased with IL-12, IL-15 or both in 18-hour cultures, but to a lesser degree compared to that on corresponding APB MNCs, (2) CD3/69 expression on CB MNCs was significantly increased after 1 week’s culture with IL-12, especially with IL-15, exceeding that on APB MNCs similarly activated and (3) CD16/69 expression on CB MNCs, but not APB MNCs, was greatly increased after 1 week’s culture with IL-15. The combination of IL-12 + IL-15 resulted in greater CB CD3/69 expression than individual cytokines, while producing less of an effect on CD16/CD69 expression as compared to IL-15 alone. The results of our study indicate that neonatal T and NK cells readily respond to cytokine stimulation by upregulating CD69 expression, with a greater effect achieved using IL-15 compared to IL-12.