Dramatic expansion and recovery of tumor specific T cells in vivo as a result of LBH589 treatment. A. Quantification of Pmel T cells recovered from splenocytes collected 10 days after adoptive cell transfer according to the treatment scheme on Figure 1A. Representative flow cytometry plots shown are derived from a lymphocyte gate followed by a live cell gate. Pmel: T reg ratios are determined by utilizing absolute numbers of Pmel T cells (CD8+ Thy1.1+) to the absolute number of T reg cells (CD4+ CD25hi FoxP3+). B. Quantification of lymphocytes within the tumor. Representative flow cytometry plots of lymphocytes isolated from subcutaneous B16 melanomas digested with collagenase 10 days following adoptive cell transfer. Dot plots shown are derived from lymphocyte and live cell gates. The Pmel: T reg ratio was calculated using absolute number of Pmel T cells and T reg cells per mg of tumor. A and B dark circles indicate mice treated with adoptive cell transfer and open squares indicate mice treated with adoptive cell transfer with LBH589 and each symbol represents one mouse. Each experiment described has been conducted two times with similar results and included at least four mice per group. Student’s t-tests were performed to determine statistical significance between groups.