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. As a result of the presence of the MHC class two complex along with the antigen shown in red and a special type of T cell known as an inactivated helper T cell which is a CD four plus helper T cell begins to approach this MHC class two antigen. Now, what do we mean by CD four? Well, CD four is simply a special type of glycoprotein that is located on the membrane of T lymphocytes and specifically on the membrane of this inactivated helper T cell.