For what it is worth:
Once thought to be an indication of lyme ( .. a ridiculous assumption IMHO ), CD57 NK cells will be effected by mercury exposure ..
This report shows the relation between low CD57 scores and workers in a fluorescent light bulb factory in Japan ...... The closer the employees were to the actual manufacturing ( ie mercury exposure ), the lower the CD57 scores ..
www.ncbi.nlm.nih.gov/pubmed/11100948