As I recall, the low end of normal is 60, so 95 sounds dandy to me...

The CD57 lymphocyte subset appears to be a useful marker of longterm infection with the Lyme disease spirochete.

PMID: 12088407

"Other unique markers for NK cells are.....CD57."

NK cells are our first line of defense against cancer.

Antibody Dependent Killer (K) and Natural Killer (NK) cells (ASCC) kill by extracellular cytotoxicity by binding to a target cell and secreting cytolysins which unidirectionally kill the target cell. Once the target is bound by an NKAR and no NKIR is activated, the cytotoxic reaction occurs. The interaction of cell adhesion molecules between NK and the target cell may tighten the attachment. The first step is a MAGNESIUM DEPENDENT movement of the cytoplasmix organelles (Golgi and granules) of the NK cell to face the target cell. The secretion of the granule contents into the intercellular space is a CALCIUM DEPENDENT step that results in the preferential insertion of perforin pores into the target cell membrane.
http://www.microimm.mcgill.ca/coursenotes/513NKILL-Note.pdf

The above link does not work anymore. However, since these are ``course notes'', I will assume this is ``common knowledge'' at the college level for those studying microbiology/immunology.

It seems there must be magnesium present for the NK cells to do their job.

But what causes them to be so low in chronic lyme?

NK cells have the ability to recognize cells that are cancerous or have been infected by a virus. The strategy used by NK cells is a drastic one-they directly approach cancerous or virally-infected cells and release strong free radicals in their immediate environment. The free radicals create a hole in the cell, and the cell then dies. The dead cell is later eaten by another kind of immune cell-the macrophages-the scavengers of the body. To leave the bloodstream and reach the tissues where they look for abnormal cells, NK cells have homing molecules on their surfaces to help detect infected cells and they use large molecules called adhesion molecules which allow them to crawl out of the blood, through the capillary wall, into the tissues.
http://users.snowcrest.net/murphyp/research.htm

Dietary magnesium deficiency in rats enhances free radical production in skeletal muscle.

In: J Nutr (1995 May) 125(5):1205-10
http://www.integratedhealth.com/infoabstract/magab.html

``Calprotectin, an abundant cytosolic protein from human polymorphonuclear leukocytes, inhibits the growth of Borrelia burgdorferi.''

Lusitani D, Malawista SE, Montgomery RR.

Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520, USA.

Calprotectin, is inside granules in neutrophils. It binds zinc, making it unavailable for pathogens to use to replicate. We become zinc deficient because most is bound to calprotectin. (The body also goes into an iron ``save'' mode for the same reason, but Bb doesn't need iron to multiply.)

Infect Immun. 2003 Aug;71(8):4711-6.
PMID: 12874352

And...

``Previous research suggests that the diminished bioavailability of zinc in older mammals may represent one of the major factors for the involution of the thymus and consequent cellular immunological dysfunction.

The influences of a variety of other hormones on the involution of the thymus have also been characterized: testosterone, estrogen, and hydrocortisone treatment results in marked involution, cortisone and progesterone administration have a slight to moderate effect while use of desoxycorticosterone has no effect.

PMID: 9891234

An ongoing magnesium deficiency resulting in thymus involution or zinc deficiency and/or an overproduction of TNF alpha and a decreased production of immunoglobulins perhaps is the cause of fewer NK cells and this can be observed using CD57 lymphocyte testing. (Updated 6/11/04 : it appears cortisol may impact the NK cells.)