In this video, we're going to do a quick review of all the immunoglobulin classes or all the classes of antibodies. So we're going to do that by completing this review table of the immunoglobulin classes. What you'll notice is that we have these five classes of antibodies arranged so that they fit our mnemonic, which is GAMED. The IgG antibody is the very first one on this list. Notice that it is a monomer and it is the standard antibody. It has a very long half-life, which means that it's very stable and will last a long time within our bodies before it's broken down. It is the most abundant class of antibody. Around 80% of all antibodies will be IgG. It has this amazing ability to cross the placenta between the mother and the baby, which is going to help provide the fetus immunity during pregnancy as well as even after birth because these IgG antibodies last such a long time that the mother's IgG antibodies in the baby will also help to protect the baby even after birth. They're also important for activating the complement system which can lead to a variety of immune responses.

Now the IgA antibody, notice it is a dimer, and a lot of times we refer to this dimer as the secretory IgA antibody or sIgA antibody. Notice that its half-life is medium, and it's going to be important for protecting the mucous membranes. It's also found in many different types of body secretions including breast milk, which can help protect the infant's intestinal system when a mother breastfeeds her baby.

The next antibody that we have on here is the IgM antibody, which is the largest class of antibody. It is a pentamer, and its half-life is medium. It is the very first antibody that is initially created by all plasma cells prior to antibody class switching. It helps to control infections in the bloodstream. That is its main role, and it also is the most effective class at activating. Its half-life is very short and so it is going to be found on both the surfaces of basophils as well as mast cells, and they're important for triggering the release of inflammatory mediators causing these basophils and mast cells to degranulate, releasing their granules into their environment. The inflammatory mediators can cause inflammation, and the IgE antibodies also play a role in allergic reactions, and we'll get to talk more about that later in our course when we focus our attention on allergic reactions and hypersensitivities. They also play an important role in protecting against parasitic infections as well, like parasitic worms, for example.

Now last but not least, we have the IgD antibody, which is again a monomer and has a short half-life, which means that it does not last very long within the body. The IgD antibodies are going to be found on the surface of B cells and they play an important role in helping to trigger B cell activation and differentiation into antibody-secreting plasma cells. And so this here concludes our brief review of the 5 classes of antibodies, and we'll be able to get some more practice applying these concepts as we move forward. So I'll see you all in our next video.