In vivo inhibition of Tregs in the bone marrow of mice treated with WP1193, IFN-α, or both. Both WP1193 and IFN-α inhibited Tregs by 31% (P<0.05) and 78% (P<0.01), respectively, compared with the control; inhibition in the peripheral blood was 20% (P<0.05) and 46% (P<0.05), respectively. However, the combination of IFN-α and WP1193 was not synergistic for Treg inhibition in either the bone marrow or the blood. The experiment was been reproduced twice at day 11 and 14 with similar findings.