FIG. 4.

CD8-derived IFN-γ production is antigen independent. Lung cells were isolated from young and old naïve mice using gentle enzymatic digestion. (A) CD11c cells were purified from young and old mice, pooled (n = 3 to 10), and cultured for 72 h with M. tuberculosis (Mtb) (MOI of 1). Cell supernatants were frozen, thawed, and filtered through a 0.2-μm filter. Supernatants were cultured with purified CD8 T cells (n = 3 to 7, pooled) from young and old mice for 48 h. (B) CD11c cells were purified from young wild-type (n = 5) and young β₂m knockout (β₂mKO) (n = 5) mice and pooled by group. CD11c cells were infected with M. tuberculosis (MOI of 1) and cultured with CD8 T cells that were purified and pooled from old mice (n = 10) for 48 h. IFN-γ was quantified in culture supernatants by ELISA. Data are represented as pg/ml of IFN-γ and are representative of data from at least two individual experiments. nd, not detected; TCM, tissue culture media.