Significance
This study shows that bone marrow-derived mononuclear cells (BMDMCs) are as effective as bone marrow-derived mesenchymal stromal cells (MSCs) in ameliorating experimental asthma. It also demonstrates that not only MSCs present in the pool of BMDMCs are responsible for BMDMCs' beneficial effects but also monocytes, which are the most important cell population to trigger these effects. All of this is in the setting of a clinically relevant model of severe allergic airways inflammation and thus provides further support for potential clinical use of cell therapy using MSCs, BMDMCs, and also adult cells such as monocytes in patients with severe asthma.