Now, recall from our discussion on white blood cells and specifically on T lymphocytes, we said that one of the specialized types of T lymphocytes that contains a CD four glycoprotein are the helper T cells of our adaptive, our acquired immune system. So recall that helper T cells are CD four positive cells. And what that means is these HIV agents will be able to bind and will be able to attack these helper T cells. So these are the helper T cells that HIV actually attacks. So let's take a look at the following diagram. We have the HIV agent that uses the GP 120 glycoprotein to bind onto the CD four Glycoprotein of this healthy helper T cell.