The interaction between the endocrine and immune systems is a very intriguing area.
Endogenous glucocorticoids, as end-effectors of the hypothalamo-pituitary-adrenal
axis, inhibit the immune and inflammatory responses and are used as immunosuppressive
drugs in many inflammatory, autoimmune and allergic diseases. The aims of this study
were to investigate the effects of dexamethasone on the profile of cytokine secretion
in whole blood cell cultures from healthy subjects and to analyse the gender-related
sensitivity to dexamethasone on each cytokine secretion.
There was a significant inhibition by dexamethasone (from 1 to 100 nM) on the secretion
of monokines (IL-1beta, IL-6, IL-8 and TNF alpha) and lymphokines (IL-2, IL-4, IL-10
and IFN gamma), either after LPS or PHA stimulation (P < 0.01). Interleukin 4 and
IL-10 were less inhibited than IFN gamma (P < 0.05 at 1 nM, P < 0.01 at 10 nM and
P < 0.001 from 100 nM to 10 microM). No gender difference was observed in the rate
of inhibition of the secretion of each cytokine.
This study shows that the inhibition of cytokine secretion by dexamethasone is more
marked on Th1-type cytokines than on Th2-type cytokines. These data support the idea
that glucocorticoids may induce a shift from the Th1 to Th2 profile of cytokine secretion.