Robertson, S. J., R. J. Messer, A. B. Carmody, R. S. Mittler, C. Burlak, and K. J. Hasenkrug. 2008. CD137 costimulation of CD8+ T cells confers resistance to suppression by virus-induced regulatory cells. J. Immunol. 180: 5267–5274 .

In the Materials and Methods section, there are typographical errors in the fifth sentence of the paragraph under the heading In vitro suppression assay. The sentence should read as follows: “All cocultures were done with 6–8 × 105 CD4+CD25+ T cells and 3–4 × 105 CD8+ T cells in flat-bottom 96-well plates.