Tierney Lorenz, Indiana University – Sex and the Immune System

Regular sexual activity can be a boon to your immune system.

Tierney Lorenz, visiting research scientist at Indiana University, discusses her research into sex and the immune system.

Tierney Lorenz is a visiting research scientist at the Kinsey Institute for Research in Sex, Gender, and Reproduction at Indiana University, where she studies the relationship between sexual behavior and symptoms of mood disorders.

As a researcher on the Women, Immunity and Sexual Health, or WISH, Study, Lorenz also studies how the presence or absence of sexual activity may influence immune response in healthy human females across the menstrual cycle, and if men and women differ in immune response to partnered sexual activity. Recently, she published a pair of studies in the journals Fertility and Sterility and Physiology and Behavior reporting sexual activity triggers physiological changes in the body that increase the types of immunity that promote fertility.

Prior to joining IU, Lorenz’s work focused on research related to antidepressant use, sympathetic nervous system activity and genital arousal; writing-based therapies to improve sexual wellbeing in women with mood disorders; and studies on the frequency of sexual activity and immunologic markers in men and women with and without mood disorders.

She is the recipient of the Hogg Foundation for Mental Heath’s Frances Fowler Wallace Memorial Dissertation Award, the International Society for the Study of Women’s Sexual Health’s Björn Lundquist New Investigator Award and the National Institute of Mental Health’s Ruth L. Kirschstein National Research Service Award.

As a clinician, Lorenz has served as a military sexual trauma team member with the Central Texas Veterans Healthcare System and a private practitioner in Austin, Texas.

She holds a Ph.D. and a master’s degree in clinical psychology from the University of Texas at Austin and bachelor’s degrees in both psychology and Japanese language and literature from Duke University.

Sex and the Immune System

For a long time, doctors and scientists regarded the immune system as reactive – a defense system only stirred to action by outside invaders.

But growing evidence suggests the immune system isn’t reactive, it’s proactive — you might even call it “socially aware.”

That’s precisely what we found recently when we looked at the role that sexual activity plays in women’s immunity.

Last year, my colleagues and I recruited a group of women — half of whom were sexually active, half of whom were abstinent — and tracked their immune systems over 30 days, taking blood samples at several points in their menstrual cycles.

We found that sexual activity predicted changes in the immune system, making the immune system act in ways that promotes pregnancy.

We found sex changed the type of antibodies in body, reducing some of the antibodies that live in mucosal linings, like in the vagina — where they would normally to attack sperm as “invaders” — and raising some antibodies that live in the bloodstream, where they can fight infection without affecting fertility.

Sex seemed to boost immune cells and antibodies that make the body more accepting of pregnancy, and reduced a type that fights off sperm and eggs. These changes all happened at the time of the menstrual cycle when they were most critical for helping a healthy pregnancy get started.

Most tellingly, these changes only occurred in the women who were sexually active. The immune systems of abstinent women stayed the same across their whole cycle, always keeping their guard up.

We still don’t know what it is that tells the immune system someone’s having sex. It is hormones; brain activity; or exchange of healthy microbes between partners? We have a lot of research ahead of us.

But, for now, everyone should give new consideration to our flexible, powerful, socially aware immune system.