Now, the macrophage is actually a type of cell we call APC, or antigen presenting cell. And what that means is, after it kills off and breaks down that cell, it takes one of the antigens, one of the proteins or nucleic acids or polysaccharides from that bacteria, and it places it onto the surface of that cell. But it places it onto a special type of complex of proteins known as MHC, which we spoke about previously. So recall that MHC stands for the major histocompatibility complex. And this is a class two complex because it's used to actually communicate with other leukocytes, as we'll see in just a moment. So this antigen presenting cell aromacrophage creates the MHC class two complex.