Degranulatory action of estradiol on blood eosinophil leukocytes in vivo and in vitro

Effect of Hormone Replacement Therapy on Chronic Rhinosinusitis Management

OBJECTIVES

To investigate whether hormone replacement therapy (HRT) impacts health care resource utilization in the management of chronic rhinosinusitis (CRS) in older women.

METHODS

Using the TriNetX US health record database, women 55 years or older with a diagnosis of CRS were included and followed for 3 years. The cohort was stratified into two groups: women who received HRT at the beginning of the study were compared to women who did not receive HRT. The groups were matched by age, race, ethnicity, history of asthma, and history of nasal polyps. Outcomes included whether the patient underwent endoscopic sinus surgery (ESS) and frequency of antibiotic use. Measures of association, Kaplan-Meier analysis, and cohort descriptive statistics were calculated.

RESULTS

Of the 65,400 women included, the mean age was 66.9 years. 27.0% and 3.6% of patients had a history of asthma or nasal polyps, respectively. Overall, 2.0% of CRS patients underwent ESS, with the HRT group less likely to undergo ESS [OR: 0.28; 95% CI: (0.25-0.32)] compared to patients who did not receive HRT. When stratified by polyp status, HRT patients with nasal polyps had a greater decrease in ESS rates compared to control than HRT patients without nasal polyps. The HRT group had a higher mean number of antibiotic prescriptions compared to the non-HRT group.

CONCLUSION

HRT is associated with decreased utilization of ESS to treat CRS, with a greater effect size for ESS among CRSwNP patients. However, HRT was associated with higher antibiotic utilization.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:3921-3926, 2024.

Sex-based differences in severity of chronic rhinosinusitis as reported by SNOT-22 scores

OBJECTIVES

Chronic rhinosinusitis (CRS) is a widely prevalent condition, however its degree of severity according to sex requires further study. The literature shows that sex-based differences exist in the severity of asthma and allergic airway disease in the population. These findings point to a potential hormonal cause for this difference, but there is no study suggesting the role of sex in CRS with nasal polyps (CRSwNP). The purpose of this study was to examine the association of sex and CRSwNP severity in the United States.

METHODS

This study was conducted on data gathered from 181 participants in the NAVIGATE I and NAVIGATE II randomized control trials within the OPTINOSE database. Participants were analyzed based on sex controlling for airway-related comorbidities, including history of asthma, race, and ethnicity. SNOT-22 scores were assessed as a quality-of-life outcome measure for CRS. The association between sex and SNOT-22 scores was determined using multiple linear regression.

RESULTS

There were 81 female and 100 male participants. SNOT-22 scores were significantly higher in females. The average reported SNOT-22 score was 53.8 ± 16.5 in females and 46.8 ± 18.8 in males. On adjusted regression, the association of sex and SNOT-22 scores approached but didn't reach significance (β: -4.97; 95 % CI: -10.68-0.73; p = 0.09).

CONCLUSIONS

On average, females had more severe manifestations of CRSwNP in comparison to males, with the adjusted association approaching statistical significance. Further studies, potentially looking at hormones as a cause of pathogenesis, are needed to better elucidate the role of sex in CRSwNP.

Eosinophilia in cancer and its regulation by sex hormones

Gender differences in the functionality of the immune system have been attributed, in part, to direct and indirect effects of sex steroids, especially estrogens, on immune cell repertoire and activity. Notable are studies that have defined roles for estrogens in the regulation of the biology of dendritic cells (DCs), macrophages, T cells and natural killer (NK) cells. Although estrogens can modulate eosinophil function, the mechanisms by which this occurs and how it contributes to the pathobiology of different diseases remains underexplored. Furthermore, although the importance of eosinophils in infection is well established, it remains unclear as to how these innate immune cells, which are present in different tumors, impact the biology of cancer cells and/or response to therapeutics. The observation that eosinophilia influences the efficacy of immune checkpoint blockers (ICBs) is significant considering the role of estrogens as regulators of eosinophil function and recent studies suggesting that response to ICBs is impacted by gender. Thus, in this review, we consider what is known about the roles of estrogen(s) in regulating tissue eosinophilia/eosinophil function and how this influences the pathobiology of breast cancer (in particular). This information provides the context for a discussion of how estrogens/the estrogen receptor (ER) signaling axis can be targeted in eosinophils and how this would be expected to influence the activity of standard-of-care interventions and contemporary immunotherapy regimens in cancer(s).

Hormonal Effects on Asthma, Rhinitis, and Eczema

Hormones significantly influence the pathogenesis of asthma, rhinitis, and eczema. This review aims to summarize relevant clinical considerations for practicing allergists and immunologists. The first section reviews the effects of sex hormones: estrogen, progesterone, and testosterone. The second concerns insulin production in the context of type 1 and type 2 diabetes. The third concludes with a discussion of thyroid and adrenal pathology in relationship to asthma, rhinitis, and eczema.

Sex Differences in Otolaryngology: Focus on the Emerging Role of Estrogens in Inflammatory and Pro-Resolving Responses

Otolaryngology (also known as ear, nose, and throat (ENT)) diseases can be significantly affected by the level of sex hormones, which indicates that sex differences affect the manifestation, pathophysiology, and outcomes of these diseases. Recently, increasing evidence has suggested that proinflammatory responses in ENT diseases are linked to the level of sex hormones. The sex hormone receptors are present on a wide variety of immune cells; therefore, it is evident that they play crucial roles in regulating the immune system and hence affect the disease progression of ENT diseases. In this review, we focus on how sex hormones, particularly estrogens, regulate ENT diseases, such as chronic rhinosinusitis, vocal fold polyps, thyroid cancer, Sjögren’s syndrome, and head and neck cancers, from the perspectives of inflammatory responses and specialized proresolving mediator-driven resolution. This paper aims to clarify why considering sex differences in the field of basic and medical research on otolaryngology is a key component to successful therapy for both males and females in the future.

Sex, Cells, and Asthma

There are marked sex differences in asthma prevalence and severity. Sex hormones play a central role in these sex biases and directly interact with multiple key cells involved in the pathogenesis of asthma. Here we review the known effects of estrogen, progesterone, and testosterone on airway epithelial cells, airway smooth muscle cells, the mononuclear phagocyte system, innate lymphoid cells, eosinophils, mast cells, T cells, and B cells, all in the context of asthma. Furthermore, we explore unresolved clinical questions, such as the role of sex hormones in the link between asthma and obesity.

Sex differences in immune responses: Hormonal effects, antagonistic selection, and evolutionary consequences

Males and females differ in both parasite load and the strength of immune responses and these effects have been verified in humans and other vertebrates. Sex hormones act as important modulators of immune responses; the male sex hormone testosterone is generally immunosuppressive while the female sex hormone estrogen tends to be immunoenhancing. Different sets of T-helper cells (Th) have important roles in adaptive immunity, e.g. Th1 cells trigger type 1 responses which are primarily cell-mediated, and Th2 cells trigger type 2 responses which are primarily humoral responses. In our review of the literature, we find that estrogen and progesterone enhance type 2 and suppress type 1 responses in females, whereas testosterone suppresses type 2 responses and shows an inconsistent pattern for type 1 responses in males. When we combine these patterns of generally immunosuppressive and immunoenhancing effects of the sex hormones, our results imply that the sex differences in immune responses should be particularly strong in immune functions associated with type 2 responses, and less pronounced with type 1 responses. In general the hormone-mediated sex differences in immune responses may lead to genetic sexual conflicts on immunity. Thus, we propose the novel hypothesis that sexually antagonistic selection may act on immune genes shared by the sexes, and that the strength of this sexually antagonistic selection should be stronger for type 2- as compared with type 1-associated immune genes. Finally, we put the consequences of sex hormone-induced effects on immune responses into behavioral and ecological contexts, considering social mating system, sexual selection, geographical distribution of hosts, and parasite abundance.

Multimodality Imaging for Spontaneous Coronary Artery Dissection in Women

Spontaneous coronary artery dissection (SCAD) has gained attention as a key cause of acute coronary syndrome and sudden cardiac death among women. Recent advancements in cardiac imaging have improved identification and accelerated awareness of SCAD. Accurate diagnosis of SCAD through use of imaging is critical, as emerging evidence suggests that the optimal short- and long-term management strategies for women with SCAD differs substantially from that of women with atherosclerotic coronary disease. This review summarizes the application of both invasive and noninvasive imaging for the diagnosis, assessment, surveillance, and treatment of women affected by SCAD.

Heavy Lifting Causing Spontaneous Coronary Artery Dissection with Anterior Myocardial Infarction in a 54-Year-Old Woman

Spontaneous coronary artery dissection in association with strenuous exercise and weightlifting is rather sparsely described in the medical literature. Diagnosis and treatment of this rare condition is a challenge, but prompt recognition and appropriate early choice of angioplasty or surgery can lead to a good outcome. We report the case of a postmenopausal 54-year-old woman who presented with anterior myocardial infarction caused by spontaneous dissection of the left anterior descending coronary artery after she had lifted a heavy weight while gardening. The patient was treated successfully by means of angioplasty and the implantation of 3 drug-eluting stents. In addition to presenting the patient's case, we review the topical medical literature.

Estrogen Signaling Modulates Allergic Inflammation and Contributes to Sex Differences in Asthma

Asthma is a chronic airway inflammatory disease that affects ~300 million people worldwide. It is characterized by airway constriction that leads to wheezing, coughing, and shortness of breath. The most common treatments are corticosteroids and β2-adrenergic receptor antagonists, which target inflammation and airway smooth muscle constriction, respectively. The incidence and severity of asthma is greater in women than in men, and women are more prone to develop corticosteroid-resistant or “hard-to-treat” asthma. Puberty, menstruation, pregnancy, menopause, and oral contraceptives are known to contribute to disease outcome in women, suggesting a role for estrogen and other hormones impacting allergic inflammation. Currently, the mechanisms underlying these sex differences are poorly understood, although the effect of sex hormones, such as estrogen, on allergic inflammation is gaining interest. Asthma presents as a heterogeneous disease. In typical Th2-type allergic asthma, interleukin (IL)-4 and IL-13 predominate, driving IgE production and recruitment of eosinophils into the lungs. Chronic Th2-inflammation in the lung results in structural changes and activation of multiple immune cell types, leading to a deterioration of lung function over time. Most immune cells express estrogen receptors (ERα, ERβ, or the membrane-bound G-protein-coupled ER) to varying degrees and can respond to the hormone. Together these receptors have demonstrated the capacity to regulate a spectrum of immune functions, including adhesion, migration, survival, wound healing, and antibody and cytokine production. This review will cover the current understanding of estrogen signaling in allergic inflammation and discuss how this signaling may contribute to sex differences in asthma and allergy.

Postpartum spontaneous dissection of the first obtuse marginal branch of the left circumflex coronary artery causing acute coronary syndrome: a case report and literature review

INTRODUCTION

Spontaneous coronary artery dissection is a rare but important cause of acute coronary syndrome. It can cause unstable angina, acute myocardial infarction, and sudden death. The condition commonly affects young females with about one-third of the cases occurring during pregnancy and the peripartum period. The diagnosis may occasionally be overlooked as the patients are often young and have no risk factors for coronary artery disease.

CASE PRESENTATION

Here we report the case of a 29-year-old African American woman who presented with acute coronary syndrome due to spontaneous dissection of the first obtuse marginal branch of the left circumflex coronary artery at three weeks post-partum and recovered requiring only medical management, possibly by longitudinal distribution of the intramural hematoma leading to good distal flow.

CONCLUSIONS

Spontaneous coronary artery dissection should be suspected in all young multiparous females presenting with chest pain in the peripartum period even in the absence of risk factors. Urgent diagnosis by angiography is required. It is recommended that treatment should be tailored to meet individual circumstances. Patients who present with single-vessel disease and hemodynamic stability, and who receive medical treatment with anticoagulation, nitrates and a beta-blocker, should experience good results.

Do extracts of oral soybean augment the trophic effect of estrogen on the rat uterus?

OBJECTIVE

To evaluate whether soybean extracts and estrogens present additive effects on adult rat uterus.

METHODS

Fifty ovariectomized rats were randomly divided into five equal groups of ten animals: Control, treated with vehicle; SE46 and SE120, treated with 46 and 120 mg/kg soybean concentrated extract (SE), respectively; EE, treated with conjugated equine estrogens (CE) 50 μg/kg; SE120 + EE, treated with 50 μg/kg (CE) plus 120 mg/kg SE. The substances were administered daily by gavage for 21 consecutive days. Thereafter the animals were weighed and killed by decapitation; trunk blood was collected for hormone determinations. Uteri were removed immediately and fixed in 10% formaldehyde, followed by dehydration, embedding in paraffin and 6-m sections staining with hematoxylin and eosin for histomorphometric analyses of myometrium and endometrium. After ANOVA analysis of the data, the study was complemented with the Tukey-Kramer test for multiple comparisons.

RESULTS

The concentrated extract of soybean at high concentration (SE 120 kg/mg) and estrogens proved to have a trophic effect on the uterus (endometrium and myometrium) of castrated rats. In groups SE120, EE and SE120 + EE, all morphometric parameters examined (number of glands, eosinophils, blood vessels and the glandular area) were increased. No significant addictive effects of soybean extract plus estrogens were detected in the SE120 + EE group.

CONCLUSIONS

Our results indicate that soy extract has a trophic effect on rat uterine structures. Treatment of ovariectomized rats with a concentrated soy extract in combination with conjugated estrogens had no addictive effect on the uterine response.

Daidzein-estrogen interaction in the rat uterus and its effect on human breast cancer cell growth

Sex hormone replacement therapy provides several advantages in the quality of life for climacteric women. However, estrogen-induced cell proliferation in the uterus and mammary gland increases the risk of cancer development in these organs. The lower incidence of mammary cancer in Asian women as compared with Western women has been attributed to high intake of soy isoflavones, including genistein. We have previously shown that genistein induces an estradiol-like hypertrophy of uterine cells, but does not induce cell proliferation, uterine eosinophilia, or endometrial edema. It also inhibits estradiol-induced mitosis in uterine cells and hormone-induced uterine eosinophilia and endometrial edema. Nevertheless, genistein stimulates growth of human breast cancer cells in culture; therefore, it is not an ideal estrogen for use in hormone replacement therapy (HRD). The present study investigated the effect of another soy isoflavone, daidzein (subcutaneous, 0.066 mg/kg body weight), in the same animal model, and its effect on responses induced by subsequent treatment (1 h later) with estradiol-17β (E(2); subcutaneous, 0.33 mg/kg body weight). In addition, we investigated the effects of daidzein (1 μg/mL) or E(2) on the growth of human breast cancer cells in culture. Results indicate that daidzein stimulates growth of breast cancer cells and potentiates estrogen-induced cell proliferation in the uterus. We suggest caution for the use of daidzein or formulas containing this compound in HRD. Future research strategies should be addressed in the search for new phytoestrogens that selectively inhibit cell proliferation in the uterus and breast.

Effect of prenatal exposure to lead on estrogen action in the prepubertal rat uterus

Lead is a widely spread environmental pollutant known to affect both male and female reproductive systems in humans and experimental animals and causes infertility and other adverse effects. The present paper investigated the effects of prenatal exposure to lead on different parameters of estrogen stimulation in the uterus of the prepubertal rat. In prenatally and perinatally exposed rats, estrogen-induced endometrial eosinophilia, endometrial stroma edema, and eosinophil migration towards the endometrium, and uterine luminal epithelial hypertrophy are enhanced while several other responses to estrogen appear unchanged. These effects may contribute to decrease in fertility following prenatal exposure to lead. The striking difference between most of these effects of prenatal exposure and the previously reported effects of chronic exposure to lead suggests that prenatal exposure to lead may neutralize the effects of chronic exposure to lead, providing partial protection of cell function against the adverse effects of chronic exposure to lead. We propose that the mechanism involved, named imprinting or cell programming, persisted through evolution as a nongenetic adaptive mechanism to provide protection against long-term environmental variations that otherwise may cause the extinction of species not displaying this kind of adaptation.

Genistein selectively inhibits estrogen-induced cell proliferation and other responses to hormone stimulation in the prepubertal rat uterus

Sex hormone replacement therapy helps improve quality of life in climacteric women. However, estrogen-induced cell proliferation in the uterus and mammary gland increases the risk for cancer in these organs. The lower incidence of mammary cancer in Asian women than in western women has been attributed to high intake of soy isoflavones, including genistein. Our previous work in the prepubertal rat uterus model showed that genistein (0.5 mg/kg body weight subcutaneously) caused an estradiol-like hypertrophy in myometrial and uterine luminal epithelial cells and an increase in RNA content in luminal epithelium; however, it did not induce cell proliferation, uterine eosinophilia, or endometrial edema. The present study investigated, in the same animal model, the effect of genistein administration (0.5 mg/kg body weight subcutaneously) before treatment with estradiol-17β (0.33 mg/kg body weight subcutaneously) on uterine responses that were not induced by genistein. Pretreatment with this phytoestrogen completely inhibited estradiol-induced mitoses in uterine luminal epithelium, endometrial stroma, and myometrium and partially inhibited estradiol-induced uterine eosinophilia and endometrial edema. These findings indicate that genistein protects against estrogen-induced cell proliferation in the uterus and suggest that future studies should investigate the possibility of using this agent to decrease the risk for uterine cancer after hormone replacement therapy in climacteric women.

Sex steroids as inflammatory regulators

It is becoming increasingly clear that endogenous sex steroids are key players in a range of inflammatory contexts. Androgens and estrogens have been shown to have a profound influence on the function of inflammatory cells including macrophages and on the secretion and activation of a range of plasma-borne inflammatory mediators. The menopause and polymorphisms in estrogen receptor genes have separately been shown to affect the incidence of a range of inflammatory disorders. Sex steroids themselves have been shown to be protective in certain conditions; harmful in others. This review will summarize their documented effects on inflammatory processes, with particular focus on two areas that have received much recent attention: the antiatherosclerotic properties of estrogens in females and the wound healing effects of sex steroids.

Postpartum spontaneous coronary artery dissection: An important clinical link with anticardiolipin antibody

A 34-year-old woman presented to the Emergency Department with substernal chest pain, 7 days after a normal vaginal delivery. Acute myocardial infarction was diagnosed based on ECG changes and elevated serum troponin levels. Coronary angiography revealed a spontaneous coronary dissection of the left anterior descending (LAD) coronary artery. The patient was managed medically and recovered well clinically with healing of the dissection on repeat angiography 10 days later. Of note the patient had a high titre of anticardiolipin antibody (IgM) detected and this is only the second case described in the literature of an association between spontaneous coronary artery dissection and antiphospholipid antibody syndrome.

Vernal keratoconjunctivitis revisited: a case series of 195 patients with long-term followup

OBJECTIVE

This study aimed at revisiting vernal keratoconjunctivitis (VKC) on the basis of anamnestic, clinical, immunologic, histopathologic, and followup data of 195 patients.

DESIGN

Retrospective noncomparative case series.

PARTICIPANTS

One hundred and ninety-five patients with VKC.

METHODS

Clinical evaluation and outcome in 151 of 195 patients with a median followup of 47 months. Evaluation was by telephone survey in 69 patients.

MAIN OUTCOME MEASURES

(1) Demographic, clinical, and immunologic features of VKC and their influence on the course of the disease; (2) conjunctival and corneal complications and efficacy of treatment observed during the followup period.

RESULTS

VKC is a chronic disease. More than 60% of patients had repeated recurrences all year round. Males had an earlier presentation of symptoms than females and the male/female ratio decreased with age. Major (greater than 80%) and minor (up to 80%) diagnostic criteria were defined for clinical signs and symptoms of the disease. Negative skin test or radioallergosorbent test was present in approximately 50% of patients, whereas eosinophil infiltration was a constant histopathologic finding. A marked conjunctival sensitivity to nonspecific stimuli was noted in more than one third of patients. In 6% of cases, a reduction of visual acuity resulted from corneal scarring, and in 2% of patients, steroid-induced glaucoma was observed. The large size of giant papillae indicates poor prognosis for the persistence of the disease and its evolution into a chronic, perennial condition.

CONCLUSIONS

VKC is a chronic eosinophilic disease of the ocular surface involving IgE, non IgE-mediated mechanisms, and age-sex-related influences. Although the disease has a good prognosis, severe visual impairments may result from long-standing inflammation.

Modulation of myofascial pain by the reproductive hormones: a preliminary report

STATEMENT OF PROBLEM

The predominance of myofascial pain in women in childbearing years suggests that the reproductive hormones may play a role in this pain disorder.

PURPOSE

The potential influence of these hormones on myofascial pain was evaluated.

METHODS

Pain patterns were compared across three consecutive menstrual cycles in oral contraceptives users (OC group) and nonusers (Non-OC group).

RESULTS

Preliminary results showed that within menstrual cycle variability of daily pain was higher than the nonusers group. In addition to their low variation, pain levels of oral contraceptives users remained positive across the hormonal cycle, whereas in nonusers, peaks of pain alternated frequently with pain-free periods. These data suggest that pain levels in oral contraceptives users may be more constant than those of nonusers.

CONCLUSIONS

This potential hormonal influence on myofascial pain levels among oral contraceptives users may represent one of the various adverse effects induced by oral contraceptives at the trigeminal area in sensitive subjects. Evidence supporting the link between estrogen, nitric oxide, and inflammatory processes is presented.

Estrogen and progesterone receptors in vernal keratoconjunctivitis

PURPOSE

Sex-related influences have been implicated in the pathogenesis of vernal keratoconjunctivitis (VKC), an allergic eosinophilic disease.

METHODS

The authors evaluated tarsal and bulbar conjunctival biopsies from seven patients with severe and symptomatic VKC for the presence of estrogen and progesterone receptors by using monoclonal antibodies with a peroxidase-antiperoxidase technique.

RESULTS

Both the epithelium and subepithelium of the tarsal and bulbar conjunctiva of patients with VKC, but not those of four nonatopic control subjects, showed intense positive staining for estrogen and progesterone receptors. Immunofluorescence colocalization of both estrogen and progesterone receptors with eosinophil cationic protein showed that approximately 70% of positive cells were eosinophils.

CONCLUSIONS

Sexual hormones, through their receptors, may influence the activity of eosinophils in patients with VKC.

Immunohistochemical localization of the eosinophil major basic protein in the uterus horn and cervix of the rat at term and after parturition

Distribution of the eosinophil major basic protein (MBP) was studied in the rat uterus horn and cervix by means of immunohistochemistry using an antiserum raised against rat MBP. Various hormonal contexts were investigated: pre- and post-parturition, the estrous cycle, and ovariectomy followed by hormonal treatment or without treatment. MBP was detectable in the cervix as early as 12 h post-partum, appearing in the stroma close to the myometrium. The MBP had spread throughout the stroma toward the luminal epithelium after a few days. In contrast, no MBP was seen in sections of the corresponding pre- and post-partum uteri and in the pre-partum cervix. In cycling rats, MBP was distributed equally in the cervix and uterus and was more abundant during proestrus and estrus. In ovariectomized rats subsequently treated with progesterone, no MBP was detected in the cervix or uterus. In the cervix of ovariectomized rats treated with estradiol, MBP first appeared in the muscle layer situated between the two cervical lumina and then reached the stroma; within a few days only the stroma was stained. Inversely, in the uterus MBP-staining first appeared in the stroma. In conclusion, analysis of the distribution of MBP in rat uterus revealed a marked difference in the response of the cervix and horn to a hormonal environment.

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.

Effect of ketotifen on the distribution and degranulation of uterine eosinophils in estrogen-treated rats

Eosinophil leukocytes migrate from the blood to the uterus under estrogen stimulation, redistribute through uterine extravascular compartment, degranulate in the organ, and release agents that are involved in several parameters of estrogen action. Agents that induce blood eosinopenia, block their migration to the uterus, interfere with their redistribution within the organ or modify their degranulation, selectively interfere with eosinophil-mediated responses to estrogen. The present study investigated whether ketotifen, an antiallergic agent that inhibits allergen-induced eosinophil degranulation, interferes with estrogen-induced eosinophil migration to the uterus and their subsequent degranulation. Ketotifen does not interfere with estrogen-induced eosinophil accumulation in the uterus, but decreases the proportion of eosinophils located in endometrium and inhibits their degranulation. These results suggest that neither histamine, calcium or slow reacting substance of anaphilaxis are involved in eosinophil migration to the uterus. The inhibition by ketotifen of eosinophil degranulation may diminish eosinophil migration through extravascular compartment via a decrease in the release from degranulating eosinophils of enzymes required for this migration. It is possible that the inhibition by ketotifen of both, eosinophil degranulation and eosinophil motility through uterine extravascular compartment, interfere with eosinophil-mediated responses to estrogen or with other functions of these cells.