Mk. Matyszak et al., Differential effects of corticosteroids during different stages of dendritic cell maturation, EUR J IMMUN, 30(4), 2000, pp. 1233-1242
Dendritic cell (DC) maturation is a complex process involving many cell fun
ctions. We have studied how the exposure of DC to corticosteroids at differ
ent stages of DC maturation affects priming and the expansion of different
subsets of CD4(+) T cells. Growth factor-dependent DC lines and fresh bone
marrow-derived DC were used. When exposed to inflammatory stimuli, immature
DC previously treated with dexamethasone were unable to undergo full matur
ation and were unable to prime Th1 cells efficiently. There was specific an
d significant reduction in the number of IFN-gamma-producing effector cell
(shown by intracellular cytokine staining) and also in the amount of IFN-ga
mma produced. Interestingly, the number of IL-4-producing T cells and the a
mount of IL-4 synthesis was not significantly altered. Furthermore, multipl
e restimulation of T cells with these DC gave rise to a subpopulation of T
regulatory cells (Tr1) which were negative for IFN-gamma and IL-4 but were
IL-10 positive. In contrast, when DC were activated with lipopolysaccharide
prior to dexamethasone treatment, the suppressive effect of glucocorticoid
s was not significant. Thus, the stage of DC maturation influences the inhi
bitory effect of corticosteroids. By arresting DC maturation, corticosteroi
ds strongly reduce cell-mediated Th1 responses and allow the selective expa
nsion of Tr1 cells.