immunecheckpoint

An immune checkpoint is a regulator of the immune system. These checkpoints are crucial for maintaining self-tolerance and preventing autoimmune diseases by preventing T cells from attacking the body's own cells. They act as "brakes" on the immune response, ensuring it is appropriately controlled and doesn't become overly aggressive. Immune checkpoints are proteins found on immune cells, such as T cells, and also on other cells in the body. When these proteins interact, they send signals that can either inhibit or activate an immune response.

The most well-known immune checkpoints are PD-1 (programmed cell death protein 1) and CTLA-4 (cytotoxic T-lymphocyte-associated protein 4). PD-1 is primarily expressed on activated T cells and binds to ligands like PD-L1, which are often found on tumor cells or healthy tissues. This interaction typically results in the suppression of T cell activity. CTLA-4 is another inhibitory receptor on T cells that competes with CD28 for binding to B7 molecules on antigen-presenting cells, thereby dampening T cell activation.

Understanding immune checkpoints has revolutionized cancer immunotherapy. By developing drugs that block these checkpoint proteins, known as immune checkpoint inhibitors, researchers have found ways to "release the brakes" on the immune system, allowing T cells to more effectively recognize and attack cancer cells. This approach has shown remarkable success in treating various types of cancer.