Downregulation of exogenous Stat5a leads to clearance of excessive granulocytes in circulation and in the lung as well as restoration of a normal progenitor pool.

<p>A. Relative contribution of myeloblasts and immature and mature granulocytes among the total number of splenocytes (left panel) and numbers of long-term hematopoietic stem cells (LT-HSC) as well as common myeloid (CMP), granulocyte-macrophage (GMP), and megakaryocyte-erythrocyte (MEP) progenitors in the bone marrows of diseased MMTV-tTA TetO-Stat5 <i>Stat5</i>^{Δ<i>N/</i>Δ<i>N</i>} mice and their controls. B. Changes in the number of granulocytes in five diseased animals that were treated for 14 days with Dox. C. Numbers of hematopoietic stem cells and progenitors in a wildtype control and a diseased MMTV-tTA TetO-Stat5 <i>Stat5</i>^{Δ<i>N/</i>Δ<i>N</i>} mouse following Dox administration. D. Sections of lung tissues from diseased MMTV-tTA TetO-Stat5 <i>Stat5</i>^{Δ<i>N/</i>Δ<i>N</i>} mice prior to and following downregulation of Stat5 (±Dox). The right panel shows the lung of a mouse treated with ampicillin to control for nonspecific effects of Dox as an antibiotic as opposed to its direct control of Stat5 expression. Bars represent 100 µm (left, middle) and 200 µm (right).