License to subdue – Publication in Blood Advances
License to subdue
It has long been a puzzle how monocytes can execute entirely opposing immunological programs by either fostering or suppressing inflammation. This puzzle has now been solved in a collaboration project with the group of Prof. Manfred Lutz at the Institute of Immunobiology at Würzburg University.
A new publication reveals that the fate and effector functions of differentiating monocytes all depend on the right timing: Early in an immune response, when monocytes encounter activated T cells producing the important cytokines GM-CSF and IFN-γ at inflammatory sites, they differentiate into activated macrophages or dendritic cells and enhance the immune response. However, later in an immune response, monocytes within the bone marrow or spleen are exposed to systemically elevated GM-CSF cytokine levels before they encounter IFN-γ-producing T cells. This means that a two-step licensing process takes place that monocytes can turn into immunosuppressive cells, which are also termed myeloid-derived suppressor cells.