Checkpoint Inhibitors in Kidney Transplant Recipients and the Potential Risk of Rejection

The immune system utilizes checkpoints to maintain self-tolerance or to prevent collateral tissue damage during an immune response. The immune system recognizes and eliminates cancer cells; however, cancers can develop multiple strategies to suppress this immune response. Cancers can alter the normal control mechanisms used to enforce peripheral self-tolerance, such as cytotoxic T-lymphocyte-associated protein 4 (CTLA4)-mediated suppression by regulatory T cells. They can also mitigate chronic inflammation through programmed cell death protein-1 (PD1)-mediated exhaustion of antitumor cytotoxic T lymphocytes.