CD34 and head and neck squamous cell carcinoma: In a phase IB study, treatment with oral Vit D3 in patients with HNSCC was shown to reduce the number of immune suppressive CD34+ cells (CD11b+CD33+CD14−HLA-DR−), increase HLA-DR expression, and increase plasma IL-12 and IFN-gamma levels in vitro, which would favor an anti-tumor Th1 immune response (Lathers et al., 2004; Ugel et al., 2009).