Everything you wanted to know about the Lyme CD- 57 test ( from 2007)

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Everything You Wanted to Know About the Lyme CD-57 Test

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Everything You Wanted to Know About the CD-57 Test

.....but were too sick to ask

Ginger Savely, RN, FNP-C

San Francisco, CA

From coast to coast, frustrations abound among patients and clinicians regarding

the diagnosis of chronic Lyme disease.

Misinformed health care providers in the southern and western states consider

the infection rare and non-endemic.

They are inclined to rule out Lyme disease based on the negative result of a

laboratory test that, unbeknownst to them, is highly insensitive.In the absence

of a reliable laboratory test or adequate experience in the recognition of the

varied and complex presentations of the illness, most clinicians are

ill-equipped to diagnose chronic Lyme disease.

Many patients suffer needlessly for years, hopelessly lost in the maze of the

health care system, looking for answers and enduring the skepticism of

practitioners inexperienced

with the disease's signs and symptoms.

What is needed is a better Lyme test or some other objective measure to persuade

the practitioner to consider the diagnosis of chronic Lyme disease.

Enter the CD57 test! You may have heard the term " CD57 " tossed around

on chat groups, or your Lyme-literate health care provider may have even

explained the test to you in one of your moments of brain-fogged stupor.

What is this number that sounds more like a type of steak sauce than a lab test,

and what in the world does it have to do with Lyme disease? Let's start by going

back

to basic high school biology.

You may remember that white blood cells (a.k.a. leukocytes) are the components

of blood that help the body fight infections and other diseases.

White blood cells can be categorized as either granulocytes or mononuclear

leukocytes.

Mononuclear leukocytes are further sub-grouped into monocytes and lymphocytes.

Lymphocytes, found in the blood, tissues and lymphoid organs, attack antigens

(foreign

proteins) in different ways.

The main lymphocyte sub-types are B-cells, T-cells and natural killer (NK)

cells. B-cells make antibodies that are stimulated by infection or vaccination.

T-cells and NK cells, on the other hand, are the cellular aggressors in the

immune system and are our main focus in the discussion that follows.

Let's pause a moment and introduce something you probably never learned about in

high school biology class: CD markers. CD, which stands for " cluster

designation " , is a glycoprotein molecule on the cell surface that acts as an

identifying marker.

Think of comparing cells as comparing people. Humans are made up of innumerable

superficial identifying characteristics (such as hair color, eye color, etc.)

and so are cells. Cells probably have thousands of different identifying

markers, or CDs, expressed on their surfaces, but 200 or so have been recognized

and named so far.

Each different marker (or CD) on a cell is named with a number, which signifies

nothing

more than the order in which the CD was discovered.

On any given cell there are many different cluster designation markers (CDs),

giving each cell its unique appearance and function but also linking certain

cells by their similarities (like grouping all people with brown hair or all

people with blue eyes).

Cells that have a certain kind of CD present on their surface are denoted as +

for that

CD type (e.g., a cell with CD57 markers on its surface is CD57+). NK cells have

their own specific surface markers. The predominant marker is CD56.

The percentage of CD56+ NK cells is often measured in patients with chronic

diseases as a marker of immune status: the lower the CD56 level, the weaker the

immune system. You may have heard Chronic Fatigue Syndrome patients talk about

their CD56

counts.

A smaller population of NK cells are CD57+. A below normal count has been

associated

with chronic Lyme disease by the work of Drs. Raphael Stricker and

Winger.

No one knows for sure why CD57+ NK cells are low in Lyme disease patients, but

it is important to note that many disease states that are often confused with

chronic Lyme (MS, systemic lupus, rheumatoid arthritis) are not associated with

low CD57+ NK counts.

The good news is that for most Lyme patients the CD57+ NK level increases as

treatment progresses and health is regained. CD57 markers can also be expressed

on other kinds of cells, including T-cells, so it is important to distinguish

between CD57+ T-cells and CD57+ NK cells.

Clinicians need to be aware that many testing laboratories claiming to perform

the CD57

test are actually looking at CD57+ T-cells rather than CD57+ NK cells, which are

the cells of interest in chronic Lyme disease.

In order for a testing laboratory to measure the CD57+ NK level, it first

measures the percentage of lymphocytes that are CD57+ NK cells. Then an absolute

count is calculated by multiplying that percentage by the patient's total

lymphocyte count.

The standard normal range for the absolute CD57 NK count is 60 to 360 cells per

microliter of blood. This wide range was established based upon test results of

hundreds

of healthy patients. By these laboratory standards, a test result below 60 cells

per microliter would be considered below normal and therefore associated with

chronic Lyme disease.

However, a recent study of my Austin, TX patients has led me to believe that 100

cells per microliter is a more reliable threshold separating Lyme patients and

healthy controls.

When Drs Stricker and Winger discovered that CD57+ NK cells are low in chronic

Lyme patients and tend to increase with patients' clinical improvement, an

opportunity arose for Lyme-literate practitioners to utilize a handy tool to aid

in the diagnosis of chronic Lyme disease, to follow treatment progress, and to

determine treatment endpoint.

Just as AIDS patients have always held great store in their CD4 T-cell count,

Lyme patients now have a fairly reliable marker of the status of their illness.

It is important to remember that the CD57 result is just a number; far more

important is the patient's clinical status. An old professor of mine used to

say, " treat the patient, not the lab test! " There is still much we do not know

about the CD57 marker and what other factors may lower or raise it.

However, overall, the CD57+ NK count is a useful tool in diagnosing and treating

chronic Lyme disease in most patients. As a measure of immune status, it

provides an indirect measure of bacterial load and severity of illness.

Furthermore, in a patient who has a negative or indeterminate Lyme test but is

highly suspect for the disease, the clinician may utilize the CD57+ NK count as

one more piece in the complex puzzle of a Lyme disease diagnosis.

Postscript: If you would like your health care provider to order the CD57 NK

test for you, your blood sample needs to be drawn into an EDTA tube (lavender

top) on Monday through Thursday and sent immediately to either LabCorp in

Burlington, NC, or Clinical Pathology Laboratories (CPL) in Austin, TX. LabCorp

and CPL are the only two labs that perform this test properly. Quest does NOT.

The LabCorp test code is #505026 and is named HNK1 (CD57) Panel. The CPL test

code is #4886, CD57 for Lyme disease. The test is time-sensitive and must be

performed within 12 hours of collection, so blood should not be drawn on a

Friday or results may be inaccurate. Page 8 www.publichealthalert.org Public

Health Alert

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