Interferon-gamma producing CD4+ T cells quantified by flow cytometry as early markers for Mycobacterium avium ssp. paratuberculosis infection in cattle

Table 1 Antigen preparations used to stimulate blood cell cultures

Antigen¹	Mycobacterial species	Final protein concentration used in culture	Application
PPDb²	M. bovis	15 µg/mL	IGRA
PPDa²	M. avium ssp. avium	15 µg/mL/5 µg/mL	IGRA/IFN-γ FCA
PPDj³	M. avium ssp. paratuberculosis	5 µg/mL	IFN-γ FCA
PPDp	M. phlei	5 µg/mL	IFN-γ FCA
WCSa	M. avium ssp. avium	1.5 µg/mL	IFN-γ FCA
WCSj⁴	M. avium ssp. paratuberculosis	1.5 µg/mL	IFN-γ FCA
WCSp	M. phlei	1.5 µg/mL	IFN-γ FCA

¹PPD: Purified protein derivative, WCS: Whole cell sonicate.
²Prionics, Planegg-Martinsried, Germany.
³Kindly provided by Ch. Thoen, Department of veterinary microbiology and preventive medicine, College of veterinary medicine, Iowa state university, Ames IA, USA.
⁴Kindly provided by R. W. Waters, bacterial diseases of livestock unit, national animal disease center, ARS, USDA, Ames IA, USA.

ISSN: 1297-9716