Microbiota-Dependent Activation of CD4⁺ T Cells Induces CTLA-4 Blockade–Associated Colitis via Fcγ Receptors

Mechanistic understanding of gut immune-related adverse events has been hampered because robust colitis is not observed in laboratory mice treated with checkpoint inhibitors. The authors found that mice harboring the microbiota of wild-caught mice developed overt colitis following treatment with anti-CTLA-4 antibodies.