So the antigen begins to break down and a small portion of that antigen known as the antigenic determinant or the epitope is taking and placed on the same type of protein complex that was found on the macrophage MHC class two major histocompatibility complex, class two. So we have the antigen, we have our MHC class two complex on our B cell. What happens next? Well, what happens next is for any type of mechanism, for any type of defensive mechanism to actually take place, our B cell must react, must interact with our T cell, our T lymphocyte. So a special type of T lymphocyte known as the helper T cell that contains the complementary T cell receptor, complementary to this particular section of our antigen and MHC class two complex. And also the helper T cell must have the CD four glycoprotein to actually be able to bind, interact with the section of our B cell.