Background
CD44 was found as a surface marker in cancer stem cell (CSC) of squamous cell carcinoma of the head and neck (SCCHN); however, the immunologic properties of such CSCs have not yet been elucidated.
Conclusion
CSCs might have higher malignant potential with numerous escape strategies from immune attack.
Methods
The immunologic properties of CD44+ cancer stem-like cells were compared with those of CD44- cells using flow cytometry and enzyme-linked immunosorbent assay.
Results
CD44+ cells exhibited weak HLA-A2 and class II expression. Interestingly, downregulation of transporter antigen processing (TAP)2 was found in CD44+ cells. The CD44+ cell population produced significantly higher levels of interleukin (IL)-8, granulocyte colony-stimulating factor (G-CSF), and transforming growth factor (TGF)-β than the CD44- cell population. Moreover, CD44+ cells have been shown to not only more strongly inhibit T-cell proliferation, but also to more efficiently inhibit regulatory T cells (Treg cells) and myeloid-derived suppressor cells (MDSC) as compared with CD44- cells. Additionally, CD44+ cells suppressed Th1 responses and enhanced regulatory T cell responses.