BCG induced CD4⁺CD44^hi multifunctional T cells persist at least 18 months post vaccination.

<p>The frequencies of antigen-specific CD4⁺CD44^hi cells exhibiting all functional phenotypes of IFN-γ, IL-2 and TNF-α production were determined by ICS in the spleen (black bars) and lungs (white bars) of BCG immunized mice up to 18 months post immunization (A). Bars represent mean (±SE) frequency of these cells as a % of total CD4⁺ cells minus the responses of age matched sham control mice, n = 2–8. Pie charts (B) represent the proportion of these cells exhibiting a 1⁺, 2⁺ or 3⁺ cytokine production phenotype, at the corresponding time points.