QFT        vs.       TST
	• in vitro • multiple antigen mixes • no boosting • 1 patient visit • minimal inter-reader variability • results in 1 day • stimulate w/i 12 hrs			• in vivo • single antigen mix (PPD) • boosting • 2 patient visits • inter-reader variability • results in 2 - 3 days • read in 48 - 72 hrs