In vitro effect of hormones on the hormone content of rat peritoneal and thymic cells. Is there an endocrine network inside the immune system?

Abstract.

Objective:

The cells of the immune system contain hormones and receptors for hormones. However, the hormonal interactions between the cells are not elucidated. In the present experiments the effect of four hormones (insulin, oxytocin, gonadotropin and epidermal growth factor) on the production of three hormones (ACTH, endorphin, triiodothyronine) in immune cells was studied.

Methods:

Hormone content of peritoneal immune cells (lymphocytes, monocyte-macrophage-granulocyte group [mo-gran], mast cells) as well as thymic cells of 100 g male rats, in vitro-treated or not treated with hormones mentioned above, were determined by flow cytometry, using specific antibodies.

Results:

All of the hormones studied influenced the hormone concentration of immune cells significantly. The width of the effects was different in the following order: oxytocin > gonadotropin > EGF > insulin. In the case of oxytocin, 8/12 of the hormone/cell group were affected, while treatment with insulin affected only 4/12. The reaction measured by the hormone production was also different: ACTH production was reduced everywhere except in the insulin-thymocyte setup. Endorphin and T₃ production was always elevated. Cells of the mo-gran group were more sensitive to hormonal regulation than peritoneal lymphocytes.

Conclusion:

The results mean that immune cells can be regulated by the neuroendocrine system and could also be able to play a role in endocrine regulation. In addition, taking into account the localization of these cells in the immune organs, there is the possibility of autocrine and paracrine regulation inside the immune system. Considering that the hormones, contained or sensed by the cells of the immune system are influencing each other, the concept of a hormonal network within the immune system can be proposed.