FIG. 4.
M. tuberculosis lipoproteins costimulate memory but not naive CD4+ T cells. Memory (CD45 RO+) or naive (CD45 RA+) CD4+ T cells (105 cells/well) were stimulated with medium (none), synthetic lipopeptide Pam3CSK4 (P3C), or recombinant LprG (rLprG), along with anti-CD3 with or without anti-CD28, as indicated. IL-2 was measured in culture supernatants by ELISA. Shown are means ± the SD of three independent experiments with different donors. *, P < 0.05; **, P < 0.0001 (compared to a no-treatment control [none]).