Review argues seminal cytokines don't just carry sperm — they actively shape uterine receptivity and embryo implantation
Journal: Fertility and Sterility | Published: 2026-03-16 | Type: Review | PMID: 41850558 Authors: Robertson SA, Sharkey DJ (Robinson Research Institute & School of Pharmacy and Biomedical Science, University of Adelaide) Funding/COI: NHMRC funding (declared). S.A.R. holds consulting fees and honoraria from Cooper Surgical P/L. Both authors are listed inventors on patent WO2025015378A1 and hold pending stock options in Affinyx P/L — a company that may commercialize findings directly related to this review.
Seminal fluid is not a passive transport medium. It contains a suite of immune-regulatory cytokines — produced by the seminal vesicles, prostate, and accessory glands — that contact sperm at ejaculation and then interact with the cervix and uterus to promote embryo implantation. Cytokine concentrations vary between men and shift in response to infection, varicocele, prostatitis, diabetes, heat stress, and smoking. Elevated proinflammatory cytokines are associated with infertility, while a distinct set appears to promote fertility by conditioning the female reproductive tract.
This is a narrative review with no original data, no systematic search methodology, and no PRISMA or equivalent reporting framework. The authors are synthesizing a literature they have contributed to, which means the selection of studies is at their discretion. There is no stated search date range, no quality assessment of included studies, and no quantitative pooling. The absence of any primary data limits what can be concluded about the clinical significance of any specific cytokine.
The review usefully acknowledges its own knowledge gaps — noting that normal cytokine ranges have not been established, it is unclear which cytokines are most informative to measure, and assay standardization is unresolved. This honesty is notable, but it also means the clinical utility described remains largely aspirational.
This review maps a genuinely underappreciated biology — seminal fluid as an active immunological signal to the uterus, not just a sperm delivery vehicle — but the overlapping financial conflicts are hard to ignore. Both authors stand to profit if seminal cytokine testing becomes a commercial diagnostic, and this review reads partly as a field-building exercise for exactly that. The science is plausible and the mechanistic framework is coherent, but no clinical thresholds exist, no cytokine panel is validated, and the effect sizes that would let a clinician act on this information are absent. Worth reading as a state-of-the-field orientation; not worth treating as evidence that cytokine testing improves fertility outcomes.