increased reactivity of single immunodominant CD8(+) EBV-specific T-cell clones may occur in response to virus replication. This is from an article at PRohealth who print some good research documents http://www.prohealth.com/library/showarticle.cfm?libid=16653. The bond uni study who are looking into nk dysfunction in cfs also have found poor cd8 lymphocyte function in cfs patients, could this be the reason why EBV reactivation is common in cfs/me. My doc has used cd8 lymphocytes as a marker for ebv/cmv reactivation as viral titres arent commonly done here in the land down under, maybe he knows alot more about this stuff then other aussie docs give him credit for. A quick google of cd8 lymphocytes and ebv or cmv gives you alot of hits. If u are unable to get viral titres done and your doc says that you test positive to a past infection to ebv or cmv ie IgG antibodies, ask for a lymphocyte subset test which will measure cd8 t cells and if high then theres a good chance that they are reactivating. Also cd3 and cd56 are nk cells and if high or low there could be other infections going on, that could be said for any of the t-cells but cd8 is more specific for ebv/cmv. cheers!!!