Fig. 2.
Immune response to challenge infection. Frequency of antigen-specific cell mediated immune responses for individual subjects at various time points after oral challenges (arrows) expressed as (A) IFNγ spot forming cells (SFCs) in response to 36 h in vitro stimulation with PPD (closed circles), Ag85 (open circles) or MPB70 (open triangles) measured by ELISPOT assay. Values represent frequency of SFCs in antigen-stimulated wells after subtraction of frequency in unstimulated wells, per 106 PBMCs stimulated. (B) Concentration of IFNγ secreted into culture supernatant after 7-day in vitro stimulation with the different antigens, expressed as pg/mL after subtraction of IFNγ concentration in unstimulated wells.