Duane Hamilton. 45 Abbreviated Title: Neoadjuvant IO for HNSCC Version Date: August 31, 2022 5.1.6 Study of peripheral immune cell accumulation and function by flow cytometry Suspensions of PBMC will be subjected to standard flow cytometry techniques to assess for the accumulation and activation of select immune sell subsets. Antibody panels will test specific hypotheses related to T cell immune checkpoint expression, as well as Treg and MDSC function and mechanisms of trafficking into tumor. This work will be performed in collaboration with the Laboratory of Dr.