Cyclophosphamide conditioning decreases Treg numbers, and induces an increase in serum IL-12 and IFNγ. (A) EL4(hCD19) tumor-bearing C57BL6(mCD19^−/− hCD19^+/−) mice pretreated with the B cell depleting antibody, MB2011 induced B-cell aplasias but failed to mediate tumor eradication on subsequent infusion with 19mz⁺ T-cell infusion (B). (C) Cyclophos-phamide conditioning mediated a significant decrease in peripheral blood Tregs as assessed by flow cytometry. (D) Serum cytokine analyses of cyclophosphamide conditioned C57BL6(mCD19^−/−hCD19^+/−) mice demonstrates transient increases in IL-12p70 and IFNγ as assessed by Luminex IS100 multiplex studies. All results are representative of at least 2 independent experiments.