CD8A and neoplasm: These studies found improved activation of antigen-presenting dendritic cells (DCs) and enhanced tumor infiltration of CD4+ and CD8+ T cells in the context of favorable taxa or microbiomes (Mager et al., 2020; Matson et al., 2018; Routy et al., 2018b; Sivan et al., 2015; Tanoue et al., 2019) or, conversely, reduced proportions of IFN-γ–positive CD8+ T cells in tumors linked with non-favorable fecal microbiomes (Spencer et al., 2021).