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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Apoptosis, Blotting, Western, Cell Cycle, Cell Line, DNA Fragmentation, Estradiol, Female, HL-60 Cells, Humans, Immunoenzyme Techniques, K562 Cells, Lipopolysaccharides, Monocytes, Pregnancy, Progesterone, Proto-Oncogene Proteins c-bcl-2, Receptors, Estradiol, Receptors, Progesterone, Tumor Cells, Cultured, U937 Cells.
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Do estrogen and progesterone modulate monocyte cell cycle progression and apoptosis? Context: Pregnancy is characterized by dramatic immunologic changes most commonly characterized as suppression of cell-mediated immunity. Mechanisms of this immunosuppression are obscure but may be caused by increases in pregnancy-associated sex steroids such as 17-beta-estradiol or progesterone. Using five myelomonocytic cell lines in various stages of differentiation, the effects of 17-beta-estradiol and progesterone on cell cycling, apoptosis, and bcl-2 expression in randomly cycling cells before and after lipopolysaccharide (LPS) activation were examined. Lipopolysaccharide alone inhibited cell cycle progression in THP-1 monocyte-like cells and U-937 histiocyte-like cells. Estrogen alone produced cell cycle arrest in all myelomonocytic cells except HL-60 pro-myelocyte-like cells. Progesterone had effects predominantly on pro-myelocytic-like HL-60 cells, inducing apoptosis. Estrogen and progesterone both decreased levels of bcl-2 in KG-1alpha, HL-60, and THP-1 cells. LPS partially antagonized both estrogen-induced THP-1 apoptosis and its suppression of bcl-2 protein.
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Sex steroid-induced effects on cell cycle transition and apoptosis are potential mechanisms by which pregnancy-induced cell-mediated immune suppression may occur. Further investigation should provide a better understanding of pregnancy-induced immune changes and, perhaps, sex-based differences in monocyte function and immunologic responses. Final Decision: yes