% NK (CD56/16)

Optimal result: 1.4 – 19.4 %

Labcorp

By Healthmatters Editorial Team

Peer-reviewed sources

An elevated % NK (CD56/16) typically indicates a higher proportion of NK cells that express both CD56 and CD16, often corresponding to an increase in the CD56^dim CD16^bright subset. This population of NK cells is primarily cytotoxic, meaning they are specialized in identifying and killing virus-infected cells, tumor cells, and other abnormal cells.

What Elevated % NK (CD56/16) May Suggest:

Increased cytotoxic immune activity
– The immune system may be actively responding to a viral infection, malignancy, or cellular stress.
Viral infections
– Elevated levels are commonly seen in chronic or recent viral infections (e.g., EBV, CMV, hepatitis, or HIV), where NK cells are activated to control the virus.
Cancer surveillance
– Higher cytotoxic NK cell percentages may reflect an immune response against tumor cells, especially in early stages.
Chronic inflammation or immune activation
– Can occur in autoimmune conditions or chronic inflammatory diseases, reflecting a heightened state of immune alertness.
Immunotherapy or immune modulation
– Certain drugs or biologics that stimulate NK cells can also increase this percentage.

Important Caveats:

An elevated % NK (CD56/16) does not diagnose a specific condition on its own.
It should be interpreted alongside absolute NK cell counts, clinical symptoms, and other immune markers.
In some cases, an elevated percentage may simply reflect a shift in immune balance, not a disease state.

If your % NK (CD56/16) is elevated, it's best to discuss the result with your healthcare provider, who can interpret it in the context of your overall health and immune status

The percentage of natural killer (NK) cells expressing CD56 and CD16, also known as % NK (CD56/16), is a significant parameter in the characterization of different subsets of human NK cells. CD56 is a marker for NK cells, and its expression can vary between different subtypes.

% NK (CD56/16): What It Measures and Why It Matters

The percentage of natural killer (NK) cells expressing both CD56 and CD16—reported as % NK (CD56/16)—is an important marker used to differentiate NK cell subtypes and assess immune function.

NK cells are key components of the innate immune system, and their behavior varies based on surface marker expression:

CD56^bright / CD16^low NK cells: These cells specialize in cytokine production, immune regulation, and modulating T cell activity. They are less cytotoxic but play a central role in shaping immune responses.
CD56^dim / CD16^high NK cells: These are the cytotoxic subset, responsible for directly killing virus-infected and cancerous cells.

Measuring % NK (CD56/16) provides insight into the functional balance between immunoregulatory and cytotoxic NK cells, which is relevant in evaluating immune responses, tracking disease progression, and understanding conditions such as infections, cancer, autoimmune disorders, and immunodeficiencies.

Organize and understand all your lab results

Start organizing — $15/mo →

For Health Professionals Healthmatters Pro Multiple clients’ results in one dashboard. See Pro plans →

% NK (CD56/16)

Every lab result you’ve ever had, charted and explained.

Healthmatters is a tracker for your lab results. Upload a report from any lab, any country — every marker charted and explained.

Start with my report →

Clinical Sources & References

All our content is backed by peer-reviewed studies, academic research, and trusted medical sources. We’re committed to accuracy and transparency — see our editorial policy for details.

Article Review Log

Written by Healthmatters Editorial Team

Organize and understand all your lab results

Start organizing — $15/mo →

For Health Professionals Healthmatters Pro Multiple clients’ results in one dashboard. See Pro plans →

Healthmatters Lifetime Plan

Pay $250. Track your health forever

One payment. No renewals. Yours for life.

10,000+ biomarkers explained · trends over time

See other plans →

Secure checkout via Stripe · GDPR & HIPAA

We accept results from any lab

LabCorp Quest Diagnostics Genova Diagnostics DUTCH Test Doctor's Data Vibrant America ZRT Laboratory Cyrex Labs + any other lab

What members are saying

★★★★★ 10,000+ happy members

★★★★★

"Watching my numbers move over the years — instead of forgetting last time's results — completely changed how I manage my health."

Daniel

Member since 2022

★★★★★

"Living across several countries made keeping my lab results organized a real challenge. Healthmatters brought my results from the USA, Spain, and Germany together — 20 years of history, with long-term trends instead of scattered reports."

Ben

Member since 2021 · tracks across countries

★★★★★

"Standard lab ranges are too wide for how I practice — 'normal' isn't optimal. I set my own bands, so a client sees yellow before a marker goes officially out of range. That's the conversation I want to be having."

Dr. Alexandra

Functional medicine · 6 yrs on Pro