It's not often people get a positive test from Quest. The thought is that they don't allow enough time for the very slow growing Borrelia (Lyme) bacteria before they evaluate - but I've not called them to verify this.
The CD57 isn't a very good test for finding out if we have Lyme - or anything else for that matter other than HIV. No one knows for sure what all affects these values, so while one person that has a very low CD57 can be and feel pretty healthy, someone that is completely bed ridden can have a near normal CD57.
This is something I found on the Quest Labs site:
www.questdiagnostics.com/testcenter/testguide.action?dc=TH_LymphSubPnls