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

Effect of eosinophil-degranulating estrogens on spleen eosinophils and white pulp/red pulp ratio

A role for eosinophils in the immune reaction has not been yet established. Considering that these leukocytes accumulate in lymphoid organs under glucocorticoid stimulation, we explored the possibility that they participate in the depression of immune reactions induced by these hormones and that they degranulate to exert this action. In this context, we investigated the dose effect of three estrogens on the number and degranulation of spleen red pulp eosinophils and on the percentage of spleen cross sectional area comprising white pulp. Estradiol-17 beta or 4 (OH) estradiol-17 beta increased red pulp eosinophils at low doses: 2 (OH) estradiol-17 beta increased them at a very high dose. The three estrogens degranulated the spleen eosinophils and decreased the lymphocyte containing spleen white pulp. We propose that the decrease in white pulp is a response mediated by agents released from degranulating eosinophils under the action of estrogen. Consequently, both estrogen-induced eosinophil degranulation and estrogen-induced increase in red pulp eosinophil numbers are conditions contributing to a decrease in white pulp volume. All above evidence supports the hypothesis that eosinophils are involved in immunoregulation by diminishing the number of lymphocytes contained in lymphoid organs.

Progesterone-mediated suppression of estradiol receptors in cynomolgus macaque cervix, endometrium and oviduct during sequential estradiol-progesterone treatment

We used sequential treatment with implants of estradiol (E2) and progesterone (P) to create varied hormonal states in a group of spayed cynomolgus macaques. The reproductive tracts were removed, and nuclear and cytosolic estrogen receptors were analyzed in the cervical mucosa, endometrium, and oviducts. Nuclear receptor quantities were greater in tissues of E2-treated monkeys than in tissues of spayed animals. Sequential P treatment, even in the presence of continuous E2, decreased the amounts of nuclear and cytosolic E2 receptors. In the oviduct and endometrium, the P-mediated suppression of receptors occurred within 1 or 2 days. In the cervix, suppression occurred only if the serum P:E2 ratio was elevated to twice the amount (approximately 100:1) usually found during the luteal phase of the menstrual cycle (approximately 50:1) in this species. Of these three reproductive tract tissues, the cervix had the highest threshold for suppression by P of E2 receptors in the presence of E2.

Short-term and long-term effects of estrogen on lymphoid tissues and lymphoid cells with some remarks on the significance for carcinogenesis

Estrogens have long been thought to play a role in regulating the immune system. The difference in some types of immune responses between males and females is well-known, as is the pronounced thymic involution induced by exogenous estrogens. Estrogens stimulate some aspects of macrophage activity and, depending on dose and mitogen, inhibit or stimulate lymphocyte proliferative response in vitro. Another example is the estrogen effect on the delayed type hypersensitivity response. A broad review is given of such estrogen effects on lymphoid tissue and immune response. Most of the studies published so far are phenomenological. However, the recent description of estrogen receptors in the thymus and in some lymphocyte subpopulations, as well as a deeper understanding of regulating factors in the immune system, open the possibility of a more detailed understanding of the estrogen mechanism of interference. Estrogen effects in adults are reversible. After treating neonatal mice with the synthetic estrogen diethylstilbestrol (DES), disturbances are induced in lymphocyte populations and lymphocyte functions which are permanent and irreversible. Lymphocytes from adult, neonatally DES-treated female mice have a reduced mitogen response to ConA and LPS (T and B cell mitogen) and the delayed type hypersensitivity response is depressed. A detailed analysis demonstrated a decreased T helper cell population. The activity of Natural Killer cells is permanently reduced and this functional impairment is related to a decreased number of these cells, in turn determined at the bone marrow level. The same animals have an increased sensitivity to chemical carcinogens (methylcholanthrene) and they spontaneously develop epithelial changes in the uterine cervix which morphologically are similar to adenocarcinoma. The association between estrogen-associated malignancy and estrogen effects in lymphocyte functions deserves further study.