CD4 T cell help is not required for robust primary CD8 T cell responses to B16 melanoma.

<p>(A) Schematic diagram of treatment schedules providing either Early Help (light gray) or No Help (dark gray). (B) Mice received primary tumors and anti-CD4 (mAb GK1.5) treatment as indicated in the figure. On day 13, IFN-γ ELISPOT was performed with CD8 T cells isolated from pooled mice (n = 4–9 mice/group) using EL4 cells pulsed with either TRP-2 or irrelevant (OVA) peptides as targets. Data represent average ± SD of four replicate wells. (C) Mice received 10⁴ naïve CD8⁺ Thy1.1⁺ pmel cells one day prior to primary tumor inoculation and anti-CD4 treatment as indicated in the figure. The proportion of Thy1.1⁺ (pmel) cells among total CD8⁺ cells was determined by flow cytometry on day 13. Symbols represent individual mice and horizontal lines represent averages. Statistically significant differences were assessed by <i>t</i> test, with * <i>P</i><0.05, *** P<0.0002 and <i>NS</i> denoting <i>P</i>>0.05. Unless indicated by brackets, asterisks directly above error bars represent significant differences compared with irrelevant (OVA) peptide. Data in (B) are representative of two experiments with similar results; data in (C) are combined from two repeat experiments.