INTERLEUKIN-6 MESSENGER-RIBONUCLEIC-ACID EXPRESSION IN HUMAN ADRENAL-GLAND IN-VIVO - NEW CLUE TO A PARACRINE OR AUTOCRINE REGULATION OF ADRENAL-FUNCTION

Interleukin-6 (IL-6) is an important mediator in the interaction of th e hypothalamo-pituitary-adrenal axis with the immune system. Recently, a direct influence of IL-6 on adrenal steroidogenesis has been demons trated. Therefore, we designed a study to determine whether IL-6 is ex pressed within the normal human adrenal gland. The combination of in s itu hybridization and specific immunostaining was eminently suited to identify the cell types producing IL-6. IL-6 messenger ribonucleic aci d occurred in the inner zone of the adrenal cortex in anti-17 alpha-hy droxylase-positive steroid cells. Also, CD68-positive macrophages in t he tons reticularis showed a positive signal No reaction was seen in c hromaffin cells. We conclude that under normal conditions, IL-6 is exp ressed in specialized adrenocortical cells. Therefore, IL-6 may play a n important role as a paracrine or autocrine factor in a local immune- adrenal interaction.