This test is a blood test that measures the amount of a certain type of white blood cell (part of your immune system) that is believed by some MD's to indicate status of Lyme infection (lower number = more active infection).
Specific tech-talk: CD57 is one type of Natural Killer Cell, which is a type of Lymphocyte, that is not commonly measured -- most MD's don't know it exists or don't think it is indicative of anything significant if it is abnormal.
I hope this helps - take care,
Chronic Lyme Disease, Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication Allergies & Intolerances, Asthma, Gut issues (dysmotility, non-specific inflammation), UCTD ("Secondary Lupus-Like Syndrome"), Osteoporosis, Anemia, Lymphopenia, intermittant Pancytopenia, chronic malabsorption/malnutrition, etc.; G-J Tube; Currently TPN-dependent.
Meds: Zofran, Pulmicort, Vitamin B12 Shots, Heparin (to flush PICC line).