Impact of gender and menstrual cycle phase on plasma cytokine concentrations

Objective: The lifetime prevalence of major depression is twice as high in females as in males. Depression is known to increase at periods where there are changes in gonadal hormones. We examined pro- and anti-inflammatory cytokine levels during the normal menstrual cycle of healthy females compared to similar time points in healthy males. Methods: Plasma concentrations of interleukin (IL)-4, IL-6, IL-8, IL-10, tumour necrosis factor-α (TNF-α) and soluble IL-6 receptor (sIL-6R) were measured with enzyme-linked immunosorbent assays in healthy females during the normal ovulatory menstrual cycle and also in males at similar time points. Results: The luteal phase of the menstrual cycle is associated with increased production of sIL-6R, IL-4 and TNF-α compared to the early follicular phase. No change was observed in IL-6, IL-8 and IL-10 concentration throughout the menstrual cycle. We found IL-4 positively correlated with oestrogen while TNF-α positively correlated with progesterone. Females were found to have significantly higher concentrations of TNF-α and sIL-6R across all phases of the menstrual cycle, compared to males across similar time points. Conclusion: The normal menstrual cycle is associated with increased production of sIL-6R, IL-4 and TNF-α in the luteal phase compared to the early follicular phase. Females have significantly higher concentrations of sIL-6R and TNF-α at all time points across the menstrual cycle than males.