EFFECT OF ESTRADIOL-17-BETA ON THE EXPRESSION OF ESTROGEN-RECEPTOR MESSENGER-RNA IN HUMAN TONSILLAR CELLS

We have investigated the expression of oestrogen receptor (ER) mRNA in Ficoll-separated tonsillar cells and the changes that occur with the addition of oestradiol (OE(2)) both in the presence and the absence of the T cell mitogen phytohaemagglutinin (PHA). The amounts of ER mRNA and beta-actin mRNA in the samples were determined by slot blotting and hybridization and quantified by densitometry. The levels of ER mRNA were normalized against the beta-actin mRNA content. In the presence of OE(2) (7x10(-8)M) after a 10-h culture there was a significant decrease (P<0.05) to about 66% of the control (0-h culture) ER mRNA levels. Stimulating the cultures with PHA (1 mu g/ml), without the presence of OE(2), had no effect on the expression of ER mRNA. However, when OE(2) was present in a 10-h culture of PHA-stimulated cells, the ER mRNA level was significantly decreased (P<0.05) to about 60% of control levels. In 24-h cultures, the presence of OE(2) and/or PHA had no effect. When separated T cell preparations from the tonsils were used, no significant effects of OE(2) were seen in either the 10-h or 24-h cultures. In conclusion, OE(2) downregulates the ER content in a tonsillar mononuclear cell in vitro as it does in many primary oestrogen target cells.