title: Testosterone and immune-reproductive tradeoffs in healthy women.
abstract: Although testosterone (T) has been characterized as universally immunosuppressive across species and sexes, recent ecoimmunology research suggests that T's immunomodulatory effects (enhancing/suppressing) depend on the organism's reproductive context. Very little is known about the immune effects of T in healthy females, and even less about how reproductive effort modulates the immune effects of T in humans. We investigated how the interaction between endogenous T and sexual activity predicted menstrual cycle-related changes in several measures of immunity: inflammation (indexed by interleukin-6, IL-6), adaptive immunity (indexed by immunoglobulin A, IgA), and functional immunity (indexed by bactericidal assay). Thirty-two healthy women (sexually abstinent, N=17; sexually active with one male partner, N=15) provided saliva samples at four points in the menstrual cycle: menses, follicular, ovulation, and luteal phases. Among sexually abstinent women, T was positively associated with IL-6 across the cycle; for sexually active women, however, T was positively associated with IL-6 in the luteal phase only, and negatively associated with IL-6 at ovulation. High T predicted higher IgA among women who reported infrequent intercourse, but lower IgA among women who reported very frequent intercourse. Finally, across groups, T was positively associated with greater bacterial killing at menses, but negatively associated in the luteal phase. Overall, rather than being universally immunosuppressive, T appeared to signal immunomodulation relevant to reproduction (e.g., lowering inflammation at ovulation, potentially preventing immune interference with conception). Our findings support the hypothesis that the immunomodulatory effects of endogenous T in healthy females depend on sexual and reproductive context.
authors.affiliation: Center for Integrative Study for Animal Behavior, Indiana University, 409 N. Park Ave, Bloomington, IN 47405, United States; The Kinsey Institute, Indiana University, 1165 E 3rd St., Bloomington, IN 47405, United States; Department of Psychology, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28223, United States. Electronic address: tlorenz@uncc.edu.
authors.forename: Tierney K
authors.initials: TK
authors.lastname: Lorenz
authors.affiliation: Center for Integrative Study for Animal Behavior, Indiana University, 409 N. Park Ave, Bloomington, IN 47405, United States; The Kinsey Institute, Indiana University, 1165 E 3rd St., Bloomington, IN 47405, United States; Department of Psychological and Brain Sciences, Indiana University, 1101 E. 10th St., Bloomington, IN 47405, United States. Electronic address: jheiman@indiana.edu.
authors.forename: Julia R
authors.initials: JR
authors.lastname: Heiman
authors.affiliation: Center for Integrative Study for Animal Behavior, Indiana University, 409 N. Park Ave, Bloomington, IN 47405, United States; Department of Biology, Indiana University, 1001 E 3rd St., Bloomington, IN 47405, United States. Electronic address: gdemas@indiana.edu.
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Demas
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007070:Immunoglobulin A; D015850:Interleukin-6 / Q000032:analysis*; D008183:Luteal Phase / Q000378:metabolism; D008597:Menstrual Cycle / Q000378:metabolism*; D010060:Ovulation / Q000378:metabolism; D012463:Saliva / Q000737:chemistry; D012725:Sexual Behavior / Q000502:physiology*; D012747:Sexual Partners; D013739:Testosterone / Q000032:analysis*
chemical_list: C508600:IL6 protein, human; D007070:Immunoglobulin A; D015850:Interleukin-6; D013739:Testosterone
keywords: Female; IgA; Il-6; Immune; Immunosuppression; Inflammation; Menstrual cycle; Ovulation; Sexual activity; Testosterone