CD8A and neoplasm: Within the tumor mass, L. reuteri released indole-3-aldehyde (I3A), a dietary tryptophan catabolite, which promoted interferon gamma (IFN-γ) production through activation of the AhR within CD8+ T cells, thus, enhancing anti-tumoral immunity and boosting anti-PD-L1 efficacy (Bender et al, 2023).