Androgen-dependent sexual dimorphism of the immune system.

An androgen-dependent sexual dimorphism of the immune system was demonstrated in mice. The ration of T/B lymphocytes in the spleen was found to be significantly higher in adult females than in adult males. Furthermore, neonatal androgen administration in females gave rise to a permanent significant decrease of the T/B ratio, while neonatal castration in males resulted in a permanent increase of this ratio.