WASHINGTON Using hormonal contraceptives might weaken a woman's natural immunity to the herpesvirus, according to findings from a pilot study of healthy women aged 18-35 years.
Findings from previous epidemiologic studies suggest that women who use hormonal contraception are at increased risk for sexually transmitted infections and herpes simplex virus (HSV) shedding. Yet clinical studies have shown that "cervicovaginal lavage fluid protects against HSV, HIV, and bacteria," lead author Dr. Gail F. Shust said at the jointly held annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) and the annual meeting of the Infectious Diseases Society of America (IDSA).
Dr. Shust and colleagues from Albert Einstein College of Medicine, New York, measured anti-HSV activity and levels of immunity associated with hormonal contraception use by collecting samples of cervicovaginal lavage (CVL) fluid from 16 women once a week for 3-8 weeks. Nine women had normal ovulatory cycles and served as controls, and seven women used hormonal contraception.
When average values from the repeat CVL samples from each woman were compared, in the follicular phase, women using hormonal contraception showed significantly less anti-HSV activity compared with the controls. In the luteal phase, the difference did not reach statistical significance.
When individual fluid samples were compared (for a total of 94 samples), the anti-HSV activity in women using hormonal contraception was significantly lower, compared with the controls, in both the follicular and luteal phases.
Correlations between anti-HSV activity and specific mucosal mediators that can inhibit herpes infection were measured through a Spearman's rank correlation coefficient analysis. Based on this measure, anti-HSV activity was positively correlated with levels of human neutrophil peptides (HNPs) 1, 2, and 3 (Spearman's rho = 0.45), lactoferrin (rs = 0.52), lysozyme (rs = 0.58), and IgA (rs = 0.44).
In addition, anti-HSV activity was negatively correlated with interferon-alpha 2 (rs = −0.36). Each of these correlations was statistically significant.
The study was limited by its small size and intrasubject and intersubject variability in anti-HSV activity.
These findings may provide a biologic explanation for the epidemiologic findings of increased risk for acquisition of sexually transmitted infections, and for HSV shedding, in the setting of hormonal contraception, the researchers said. Studies of the factors that modify anti-HSV activity are ongoing, and larger, prospective studies are needed to support the results, they noted.
Dr. Shust reported no financial conflicts of interest.