CD28

CD28 is a protein found on the surface of T cells, which are a type of immune cell that helps protect the body from infections and abnormal cells. Think of CD28 as a 'second signal' or a helper switch; it provides essential stimulation that activates T cells when they recognize a foreign invader. Without this signal, T cells may not fully activate or might become tolerant instead of attacking. In immunotherapy, targeting CD28 can enhance immune responses against cancer or infections, making it an important molecule for regulating immune system activity.