The pituitary-adrenocortical axis and the immune system.

Recent findings indicate that interactions between the pituitary-adrenocortical axis and the immune system involve more than simply the effects of glucocorticoid hormones. This altered view has resulted from the observations that: 1) cells of the immune system have receptors for and are directly acted upon by ACTH and endorphins, and 2) the immune system is an important non-pituitary source of these peptide hormones. In this chapter, while we review in a cursory way the older findings with glucocorticoid hormones, we concentrate on the newer developments which suggest that leukocyte- and pituitary-derived ACTH and endorphins perform regulatory functions within and between the immune system and the pituitary-adrenocortical axis.