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. It places it on the surface and it takes an antigen which is shown in red, and it places it onto this region on the MHC class two complex. Now, what happens next is another type of leukocyte. Another type of white blood cell can now interact and communicate with the macrophage.