A specific estrogen receptor in the mouse spleen. Characterization and evidence of physiological regulation

We have used the synthetic estrogen [3H]-R2858 (11 beta-methoxy-17-ethnyl-1,3,5(10)-estratriene-3,17-diol) to characterize a cytoplasmic estrogen receptor in the mouse spleen. This receptor is specific for estrogens and binds to the steroids with high affinity. The binding is abolished by pronase or 37 C treatment, and the 8S peak is shifted to the 4S region on sucrose gradients under conditions of high salt. The concentration of spleen receptor increased significantly during pregnancy, and decreased after immunization with foreign protein. Estrogen receptors may be confined to certain subpopulations of spleen cells that change in numbers during pregnancy or after immunization.