The plus simply means these cells have this glycoprotein. Now, generally speaking, these cytotoxic T cells and all CD eight T cells are those cells that can differentiate infected cells from healthy cells and kill off those infected cells. So, to see what we mean, let's consider the following example. Let's suppose that we have the common flu and what that means is a special type of viral agent known as influenza infected our body. Now, what this virus does is it infects our healthy cells and it creates infected cells. So the infected cell begins to produce the viral agents that are needed by the virus to essentially reproduce.