Myeloid-derived suppressor cells (MDSC) are a class of immune suppressor cells that represent less than 1% of circulating cells in normal individuals.
These cells are known to accumulate in patients with cancer and their numbers seem to correlate with tumor burden. The generation of MDSC in the bone marrow and the migration of MDSC from the bone marrow to the tumor site are enhanced in response to tumor-derived factors. Research evidence indicates that immune suppressor cells are able to reduce the ability of the innate and adaptive immune system to eliminate the developing tumor.
Recent epidemiological, fundamental and clinical studies also indicate that psychological stress is implicated in the development and progression of cancer (several of these studies are reviewed here, at the BrainImmune Site).
In this study, Bethany Mundy-Bosse and colleagues from the Department of Integrated Biomedical Sciences, the Ohio State University, Columbus OH investigated the association between psychological stress and MDSC levels in post-surgical breast cancer patients. The study is perhaps the first to specifically measure levels of MDSC in post operative breast cancer patients who were considered to be macroscopically disease-free. The investigators report that when study participants were evaluated for objective, longer-term stressors by the Life Events measure of stress, patients with higher stress levels exhibited higher baseline numbers of MDSC. According to the authors, further studies are warranted to evaluate the direct effects of MDSC on natural killer (NK) and T cell function and how stress may alter these interactions. Along these lines, this study further supports the existence of a complex relationship between stress and immune function in breast cancer patients.
SOURCE: Cell Immunol, 2011, 270:80. Epub 2011 Apr 23.