Evidence that human serum with high levels of estrogens interferes with immune system both by decreasing CD25 expression on T-cell and by increasing interleukin-2 availability.

Our study aimed to verify whether serum with high estrogen levels, obtained from infertile women who underwent multiple follicular development, was able to interfere with peripheral blood mononuclear cells proliferative response to phytohemoagglutinin +/- interleukin-2, recombinant interleukin-2 alone and phytohemoagglutinin-stimulated CD25 expression. Blood samples from 10 women were collected at the onset (low estrogen doses), during multiple follicular development (intermediate estrogen doses), and on the day preceding the human chorionic gonadotropin administration (high estrogen doses). Serum with high estrogen doses reduced the proliferative response to phytohemoagglutinin alone and plus recombinant interleukin-2, while increased the proliferative response to recombinant interleukin-2 alone, and reduced the CD25 expression in nonblastic and total lymphocytes. These effects were inhibited by the estrogen receptor antagonist ICI182,780. Inconclusion, estrogens exert a dual effect on immune system: (1) an inhibition of cell-mediated immunity through a reduction of interleukin-2 receptors; (2) an increased proliferative response to interleukin-2.