Altered immune function in human newborns after prenatal administration ofbetamethasone: Enhanced natural killer cell activity and decreased T cell proliferation in cord blood

During the course of human pregnancy, glucocorticoid (GC) treatment is give n when preterm delivery is expected. This treatment is successful in stimul ating the development of the fetal lung. However, in animal studies, a numb er of side effects of perinatal GC treatment have been described. The aim o f the present study was to evaluate in humans the effects of antenatal GC t reatment on development of the immune system. In addition, we examined the development of immune reactivity in infants born preterm and at term who di d not receive GC treatment antenatally. We tested mitogen-induced T cell pr oliferation, natural killer cell activity, and lipopolysaccharide-induced I L-6 production in cord blood samples. We found that there is a significant effect of gestational age on the capacity of T cells to proliferate and of natural killer cells to kill K562 tumor cells. The capacity to produce IL-6 does not change between gestational age 26 and 41 wk. Moreover, our result s show that antenatal treatment with GC does have immunomodulatory effects: T cell proliferation is decreased in infants born very preterm (gestationa l age 26-31 wk) as well as in infants born between 32 and 36 wk of gestatio n. In contrast, the activity of natural killer cells is only increased in C C-treated infants born between 26 and 31 wk. We did not observe a significa nt effect of antenatal GC treatment on the capacity to produce IL-6.