Date on Master's Thesis/Doctoral Dissertation


Document Type

Doctoral Dissertation

Degree Name

Ph. D.


Microbiology and Immunology

Degree Program

Microbiology and Immunology, PhD

Committee Chair

Yan, Jun

Committee Member

Shirwan, Haval

Committee Member

Zhang, Huang-ge

Committee Member

Suttles, Jill

Committee Member

Uriarte, Silvia

Author's Keywords

glucan; tumor; cancer; immunity; myeloid; suppressor


Myeloid-derived suppressor cells (MDSC) are a heterogeneous population of immature myeloid cells that promote tumor progression. In this study, we investigated the effect of dectin-1 stimulation by yeast-derived particulate β-glucan in MDSC function and differentiation in cancer. In vivo treatment of mice bearing lewis lung carcinoma and mammary cell carcinoma with particulate β-glucan decreased tumor weight and splenomegaly, and reduced the accumulation of polymorphonuclear-MDSC (PMN-MDSC) but not monocytic-MDSC (M-MDSC) in the spleen and tumor. In addition, particulate β-glucan differentially modulated the function of different MDSC subsets; it enhanced PMN-MDSC respiratory burst and apoptosis, and induced the differentiation of M-MDSC into F4/80+CD11c+antigen-presenting cells in a dectin-1 dependent manner. ERK1/2 phosphorylation was also required for the acquisition of APC properties in M-MDSC. Moreover, M-MSDC treated with particulate β-glucan did not promote tumor growth in vivo when inoculated with LLC subcutaneously. To evaluate the effect of particulate β-glucan treatment in humans, patients with non-small cell lung cancer (NSCL) were treated with particulate β-glucan for two weeks prior to any other treatment and surgical excision of the tumor. Strikingly, the frequency of CD14-HLA-DR-CD11b+CD33+ MDSC decreased in the peripheral blood, and arginase-1 expression significantly decreased in a cohort of 15 patients. This study was the first to assess the effect of particulate β-glucan on MDSC in lung cancer patients, towards a future inclusion of particulate β-glucan in combination therapies in lung cancer.