Increased tumor necrosis factor-alpha in whole blood during the luteal phase of ovulatory cycles.

Objective: To evaluate whether the fact that blood from premenopausal, ovulatory women shows a significant fluctuation in tumor necrosis factor-alpha (TNF-alpha) levels when tested randomly over time is related to the hormonal cycle.
Study Design: In this pilot study, whole blood was collected from 8 women during the follicular, ovulatory and midluteal phases of the menstrual cycle. Ovulation was confirmed by luteinizing hormone surge and mid-luteal progesterone levels. For each subject at each phase of the menstrual cycle, TNF-alpha levels were measured at baseline and after stimulation of whole blood with 10 microg/mL of lipopolysaccharide (LPS). Supernatant was collected and assayed by enzyme-linked immunosorbent assay. TNF-alpha levels were compared with the Wilcoxon matched pairs signed rank sum test.
Results: Whole blood unstimulated by LPS showed increasing TNF-alpha levels over the hormonal cycle, with significantly increased median levels during the luteal phase (903 pg/mL; range, 0-3707) as compared with the follicular phase (162 pg/mL; range, 0-656) (P = .03). Blood stimulated with LPS showed increased TNF-alpha levels overall but no association with cycle timing.
Conclusion: TNF-alpha levels in unstimulated whole blood appear to be associated with menstrual cycle timing, with highest levels during the luteal phase. However, the lack of variation in TNF-alpha production after LPS stimulation suggests that experiments do not need to be timed with the menstrual cycle.