Glucocorticoids and immune function: unknown dimensions and new frontiers.

Despite the importance of glucocorticoids (GCs) to modern medicine, the physiological role of endogenous corticosteroids in immunomodulation is poorly understood. This article discusses evidence suggesting that endogenous GCs not only suppress but also direct and enhance immune functions. These often overlooked actions might well be more important than the inhibitory functions during host defence and the maintenance of homeostasis.