 So I'm bringing you back to this page that we've already looked at because I want you to remember what you already know about the MHC complex. We've looked at MHC one. It's found on all nucleated cells in your body and it's used to post information about what's going on inside the cell. MHC two is exactly the same except it's only found on certain cells and it's involved in the acquired immune response. So almost 100% of the time MHC two is somehow involved in activating the acquired immune response. So it's only found on antigen presenting cells and who are these antigen presenting cells? Well, B lymphocytes are antigen presenters and we'll talk about how they use their MHC two platform to be involved in this process. Dendritic cells are antigen presenters. Remember how we added dendritic cells into our list of non-specific phagocytes? Well, they do their non-specific phagocytotic good work and then they post their information on their MHC two platform and use that to activate T cells. What? How cool is that? I think I said macrophages. Macrophages are also antigen presenters so they can actually go around and activate acquired immune cells. Okay, so we've got these certain cells that have an MHC two platform. We've got everybody else who has the MHC one and we really do need to keep those separated. Now, we're going to buckle down and we're going to look at the humoral immune response. We're going to go from start to finish. We're going to start with our little naive little naive guy and we're going to work our way through all the things that are involved in that humoral immune response knowing that most of it is going to be about the B cells. Okay, so let's do that, shall we?