T cells contribute to the immunosuppressive function of tumor infiltrating myeloid cells.

<p>(<b>A</b>) The graphs indicate the proportion of CD45⁺ cells from live cells and myeloid cells from CD45⁺ cells from tumors of RetCD3ε⁺ (n = 15) and RetCD3εKO (n = 16) age matched mice. (<b>B</b>) Cell suspensions from tumors derived from RetCD3ε⁺ and RetCD3εKO mice were stained for CD45, CD11b and IL4-Rα. Representative histograms are shown for IL4-Rα expression from CD45⁺CD11b⁺ cells. The histograms below summarize the MFI ratio of IL4-Rα specific staining on the isotype staining. Cell suspensions were also stained for CD45, CD11b and IL-12 after LPS and IFNγ stimulation. Representative IL-12/CD11b dot plots generated from gated CD45⁺ cells are shown. The histograms below summarize the proportion of IL-12 secreting cells from tumor infiltrating CD11b⁺ cells. Purified tumor infiltrating CD11b⁺ cells were activated with LPS and IFNγ for two days and assessed for NO production (<b>C</b>). (<b>D</b>) GP33-specific T cells (as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0020235#pone-0020235-g004" target="_blank">Figure 4.A</a>) were stimulated 24 h with GP33 in presence of CD11b⁺ cells isolated from tumors of RetCD3ε⁺ (n = 5) or RetCD3εKO (n = 5) mice. T cell inhibition by myeloid cells is determined by comparing the frequency of IFNγ secreting cells in absence and in presence of CD11b⁺ cells.