Cyclic changes in the level of the innate immune molecule, surfactant protein-a, and cytokines in vaginal fluid

Our knowledge of the innate host defenses in the vagina, a site where these defenses are essential to protecting the host upper reproductive tract from invasion by pathogens, is as yet rudimentary. Specifically, little is known about the pattern-recognition component of vaginal innate immunity, the relationship of pattern-recognition molecules to known cytokine levels, and the role of gonadal hormones in their regulation.

We measured levels of Surfactant Protein-A (SP-A), a prototypic innate pattern-recognition protein, in vaginal fluid (VF) and correlated them with levels of IL-1β and IL-8, two cytokines known to be present in VF. Assays were carried out on VF collected over three consecutive cycles from ten healthy naturally cycling women who were sampled at three specific time points in the menstrual cycle. The three time points were chosen to enable correlation with distinct hormonal states.

Both SP-A and cytokines levels were highest 5-6 days after menses (P < 0.05) and were significantly lower at ovulation and mid-luteal phase.

Surfactant Protein-A, like other host defense molecules in the reproductive tract, appears to be regulated by gonadal hormones.