HNK1 (CD57) Profile Blood Test

What is the purpose of this test?

The HNK1 (CD57) Profile Blood Test is a specialized immune function test that measures the number and percentage of CD57+ Natural Killer (NK) cells in the blood. CD57 is a marker found on a specific subset of immune cells, especially on NK cells and some T cells, which play a key role in defending the body against infections, particularly viral infections like Lyme disease and chronic viral illnesses. A low number of CD57+ NK cells has been associated with chronic immune dysfunction and persistent infections, making this test useful in evaluating long-term illness that may not be identified through standard testing.

This test is commonly used in managing patients with suspected or confirmed chronic Lyme disease or other tick-borne illnesses. Many healthcare providers use CD57 levels as a biomarker for chronic immune suppression, which can guide diagnosis, track disease progression, or monitor treatment response. Because changes in CD57+ NK cell levels are linked to immune stress, this test can help detect lingering or recurring infections even when other lab results appear normal. It provides a clearer picture of how the immune system is functioning under long-term stress or inflammation.

Who should get this test?

The HNK1 (CD57) Profile Blood Test may benefit:

• Individuals with suspected chronic Lyme disease or ongoing symptoms after Lyme treatment
• Patients with long-term fatigue, joint pain, or neurological symptoms without a clear cause
• People experiencing persistent infections or recurrent viral illnesses
• Individuals being monitored for immune function during or after treatment for chronic infections
• Healthcare providers assessing immune suppression or poor recovery after infections
• Those participating in research or medical studies on chronic immune conditions

When should I order the HNK1 (CD57) Profile Blood Test?

Individuals may consider ordering this test if they have symptoms or exposure concerns related to chronic infections or immune dysfunction.

Symptoms to consider:

• Ongoing fatigue or brain fog that doesn’t improve with rest
• Muscle or joint pain with no obvious cause
• Tingling, numbness, or other unexplained nerve symptoms
• Frequent or long-lasting viral infections (like Epstein-Barr or Herpes viruses)
• Trouble recovering after infections or tick bites
• Memory problems or mood changes without a known reason

If you have these symptoms or suspect long-term immune stress or chronic infection, the HNK1 (CD57) Profile Blood Test can provide useful insights to guide your healthcare provider in understanding your immune health and planning the next steps in care.