title: Effects of hormone replacement therapy on immunological factors in the postmenopausal period.
abstract: BACKGROUND
  Despite valuable evidence documented on immunological changes in postmenopausal women, particularly following hormone replacement therapy (HRT), it is difficult to explain whether immunological changes during menopause are caused by HRT. This systematic review aimed to summarize the results of studies available on postmenopausal immunological changes and to determine any potential effects of HRT on the immunological profile of postmenopausal women.
  
  
  METHODS
  For this systematic review, we primarily explored 751 papers about the immune system status of postmenopausal women published during 1955-2015. Scientific databases including Web of Science, MEDLINE, Scopus, Embase, Google Scholar, and the Cochrane database were searched for a number of relevant key terms. Of 209 papers that met the initial search criteria, 13 papers were potentially retrievable and included descriptions of changes in immunological factors during the postmenopausal period and the effects of HRT on such changes.
  
  
  RESULTS
  HRT resulted in a range of immunological changes in postmenopausal women. These changes included reductions in interleukin-2 (IL-2), IL-6, and insulin-like growth factor-1 levels and increments in IL-1 and IL-4 levels. Elevations in B-cell production and estrogen receptor alpha, CD19+ cells, and C3 and C4 complement levels were also documented. Decreased CD8+ counts were also a constant finding in most reviewed papers. However, data on the changes in other factors such as tumor necrosis factor-alpha, interferon-gamma, CD4+, and CD25+ were contradictory. Levels of some immunological factors, e.g. immunoglobulin G (IgG), IgM, and IL-10, remained unchanged following HRT.
  
  
  CONCLUSIONS
  Postmenopausal women are prone to impaired immune responses. HRT during the menopausal period can mediate immunological responses by inducing significant changes in immunological mediators.
authors.affiliation: a Students' Research Office, Nursing and Midwifery Faculty , Shahid Beheshti University of Medical Sciences , Tehran , Iran ;
authors.forename: F
authors.initials: F
authors.lastname: Abdi
authors.affiliation: b Biomaterials Department , Iran Polymer and Petrochemical Institute , Tehran , Iran ;
authors.forename: H
authors.initials: H
authors.lastname: Mobedi
authors.affiliation: c Department of Immunology, Faculty of Medicine , Shahid Beheshti University of Medical Sciences , Tehran , Iran ;
authors.forename: N
authors.initials: N
authors.lastname: Mosaffa
authors.affiliation: d Department of Reproductive Health, Nursing and Midwifery Faculty , Shahid Beheshti University of Medical Sciences , Tehran , Iran ;
authors.forename: M
authors.initials: M
authors.lastname: Dolatian
authors.affiliation: e Reproductive Endocrinology Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences , Tehran , Iran.
authors.forename: F
authors.initials: F
authors.lastname: Ramezani Tehrani
mesh_terms: D047628:Estrogen Receptor alpha / Q000097:blood; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D007109:Immunity / Q000187:drug effects; D007136:Immunoglobulins / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007376:Interleukin-2 / Q000097:blood; D015847:Interleukin-4 / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D007378:Interleukins / Q000097:blood; D018655:Lymphocyte Count; D016239:MEDLINE; D017698:Postmenopause / Q000276:immunology*
chemical_list: D047628:Estrogen Receptor alpha; D007136:Immunoglobulins; D007376:Interleukin-2; D015850:Interleukin-6; D007378:Interleukins; D015847:Interleukin-4; D007334:Insulin-Like Growth Factor I
keywords: Menopause; hormone replacement therapy; immunological factors