Vaginal NK cells help repair the vaginal barrier

Author: Jessica Lloyd
Senior Vulvovaginal Specialist Naturopath | BHSc(N) | ISSVD, ISSWSH, BSSM, ATMS

Last reviewed: July 4, 2026

New research suggests the vagina’s natural killer (NK) cells do more than kill infected cells – they also help patch up the vaginal lining after an infection.

In a preprint from a Fred Hutchinson Cancer Center and University of Washington team, vaginal NK cells were shown to produce amphiregulin, a growth factor that supports epithelial repair, and their removal left the vaginal barrier more damaged even when the virus itself was cleared normally.¹

This is an early, not-yet-peer-reviewed finding, but a genuinely interesting one for anyone thinking about how the vagina defends itself.

Importantly, this is preprint research. It has been posted publicly and picked up as a research highlight, but it has not yet been through peer review, so treat it as a promising lead rather than settled fact.^{1, 2}

What did the study actually find?

The researchers looked at NK cells from both human and mouse vaginal tissue, alongside NK cells from blood.¹ NK cells are part of the innate immune system – the fast, first-line defence that does not need to have met a pathogen before to react.

Using single-cell sequencing and detailed cell profiling, they found that vaginal NK cells look and behave differently from the ones circulating in blood. At rest they are fairly quiet, with limited killing activity, but they are primed to respond quickly when inflammation shows up.¹

The stand-out detail is that these tissue NK cells make amphiregulin, an epithelial growth factor tied to wound healing. That is not the job people usually associate with NK cells, which are best known for detecting and destroying virus-infected cells.¹

How did they test the repair role?

In a mouse model of herpes simplex virus type 2 (HSV-2) infection, the team let the infection begin to clear, then depleted the NK cells and looked at the vaginal tissue.¹ The mice without NK cells had significantly more epithelial damage and more immune-cell infiltration than mice that kept their NK cells.

Tellingly, the extra damage happened even though the virus was cleared just as well in both groups. In other words, the worse outcome was not about failing to fight the virus – it was about the barrier itself not being maintained and repaired.¹

A dye-leakage test backed this up. When NK cells were removed, more of a small tracer dye leaked through the vaginal lining into the deeper tissue, a sign of a leakier, less intact barrier.¹ The NK-depleted animals also had much less amphiregulin in the tissue, pointing to NK cells as a key local source of that repair signal.

What switches on the repair signal?

The researchers traced the amphiregulin response back to two alarm-signal cytokines released by stressed or damaged tissue: IL-18 and IL-33.¹ Exposing human and mouse NK cells to these signals prompted them to make amphiregulin.

When the team took the fluid from these activated NK cells and applied it to a scratched layer of cells in a dish, the gap closed faster.¹ That is a lab model of wound healing, and it suggests NK-cell-derived factors can actively help tissue knit back together, not just avoid harm.

Why this matters for your vagina

The vaginal lining is a barrier, and that barrier is central to staying well. It is your physical wall against pathogens, and it works hand in glove with your protective vaginal bacteria and the rest of your vagina’s immune system. When the barrier is intact, disruptive bacteria and viruses have a much harder time getting a foothold.

What is neat about this work is the idea that immune defence and tissue repair are two sides of the same job. The same NK cells that help control an infection may also help make sure the fight does not leave the vaginal wall raw and leaky afterwards. A calmer, better-healed barrier is a barrier that is harder to reinfect.

In our clinic, so many of the recurring problems we see – the on-again-off-again bacterial vaginosis, the infections that keep coming back after treatment – come down to a barrier and a microbial community that never fully recovered.

Research like this helps explain why a full recovery, not just a cleared test, matters so much. It also fits the wider picture emerging from work such as the cervix-on-a-chip studies showing how vaginal bacteria lower STI risk.

A couple of honest caveats. This was a study of HSV-2 in mice plus profiling of human cells, so it does not tell us what to do differently today, and it does not point to any product or supplement. And because it is a preprint, the findings could shift once other scientists scrutinise them.^{1, 2}

Frequently asked questions

What are natural killer (NK) cells?

NK cells are a type of white blood cell in the innate immune system. They can recognise and destroy virus-infected and stressed cells quickly, without needing prior exposure. This research adds a second string to their bow: helping repair the tissue barrier.¹

Does this mean NK cells cause damage in the vagina?

Quite the opposite in this study. Removing NK cells led to more epithelial damage and a leakier barrier, so here they appear protective and reparative, not harmful.¹

Is this a new treatment I can get?

No. This is early-stage laboratory and animal research, not a therapy. There is nothing to buy or do based on it. It is a step in understanding how the vaginal barrier defends and repairs itself.¹

Has this been peer reviewed?

Not yet. It is a preprint, meaning it has been shared publicly ahead of formal peer review. It has been highlighted in the scientific press, but the details may change before final publication.^{1, 2}

What does amphiregulin do?

Amphiregulin is an epithelial growth factor involved in wound healing and maintaining barrier tissues. In this work, vaginal NK cells produced it in response to the tissue alarm signals IL-18 and IL-33.¹

What to do next

There is nothing to act on from this preprint yet – it is science to watch, not a to-do list. But if you keep getting infections that clear and then return, that pattern is worth taking seriously. Recurrent bacterial vaginosis (BV), genital herpes flares, or infections that never quite resolve often point to a barrier and microbiome that have not fully recovered.

If that sounds like you, a good starting point is finding out exactly what is living down there with a comprehensive vaginal microbiome test, so any treatment is aimed at the real problem rather than a guess. If you would like tailored help working out what is going on, you are welcome to book an appointment with our clinic.

This is general information, not a substitute for personalised medical advice.