 Hi everybody, Dr. O. This is going to be a quick introduction to the five different classes or types of immunoglobulins. So hopefully remember the immunoglobulins are globulin proteins will cover the actual functions of antibodies later. We'll talk about like the stuff here at the bottom of the image like where they bind to or whether or not they fix complement. I just want to introduce you to the five classes here. So you'll see that I won't go through them in order because whenever I think of the five classes of antibodies, I always think of the word gamed, G-A-M-E-D. So I want to go through them in that order. All right, so IgG, these are number one, most numerous by far. 80% of your antibodies are going to be IgG antibodies. They are effective at destroying and inhibiting bacteria, viruses, and bacterial toxins. So these are the most common and most effective antibodies we have. Another unique thing about them, these are the only ones that cross the placenta. So this is very important. All five classes of antibodies cross into breast milk, but only IgG antibodies cross the placenta. So an example here of IgGs, which can cause problems, would be the anti-RH antibodies. So your anti-A and anti-B antibodies are different. We'll come back to them in a moment. But your anti-RH antibodies can cross the placenta. That's what leads to hemolytic disease of the newborn. If you have an R-H negative mom and an R-H positive baby after the first pregnancy, when they're sensitization, you would know mom would have anti-RH antibodies that could cross the placenta. And that's what Rogam is going to desensitize that situation so there's not any problems. So that's what we knew about IgGs. So most numerous by far and also the most effective. So that's IgG. Next in Gamed, we have IgA. So I like to call these secretory IgA antibodies just because it reminds me that they are in glandular secretions. So the IgA antibodies are a dimer as you can see from the picture here. There's two of them. And they have this secretory piece that's added to them actually by epithelial cells and it's pretty cool. That's what makes them soluble. So then you're going to find them in your glandular secretions. So saliva, tears, semen, everything. Like all glandular secretions are going to have secretory IgA antibodies. So their job is to be this last line of defense to neutralize and stop pathogens before they enter your body. So you're going to find these again in all glandular secretions. So that is your IgA or secretory IgA antibodies. What do we have? Gamed. Next is IgM. As you can see here, IgMs are a pentamer. They call them a starburst. So these are going to have five of the small individual subunits make up one of them. So structurally they're going to be the largest by far. But the key thing about them is they're the first to show up. So whenever there's a new antigen, IgM antibodies are the first to show up, but they're not super effective. I feel like they basically hold back invaders long enough for the IgGs to show up and do the work. And that's why as IgG concentration goes up, IgM concentration goes down. So in another video we'll talk about primary versus secondary immune response. The primary immune response is weak because it's dominated by IgMs. It takes 10 to 14 days for the IgGs to really mount a defense. But the secondary immune response, the second time you've been exposed to something, or if you've been properly vaccinated for something, the next time you're exposed, the IgGs take over right away. And that's why you don't get the same infection a second time. And that's why you shouldn't get something that you've been properly vaccinated for. So IgMs, just remember, structurally the largest and the first to show up. Now the key example here would be your anti-A and anti-B antibodies. So these can't cross the placenta, but these are the ones that lead to your actual blood type. So your blood type, you're going to be A, B, A, B, or O depending on which antigens are on your blood cells. But the IgM antibodies would be the antibodies in your plasma. So when you think RH antibodies, think IgG. When you think anti-A, anti-B, think IgM. All right, that's GAM. So next we're on to IgE. So IgE antibodies are going to be, they're going to dock on the surface of mast cells and basophils. So hopefully remember them from earlier discussions. Mast cells and basophils are the cells that are full of histamine and heparin, so they both lead to the inflammatory response. So basophils are the white blood cells that release histamine and heparin and mast cells, MAST, mast cells do the same thing. So when you think IgE antibodies think inflammation, inflammatory response, but then also allergic reactions and the allergic response. So that is your IgE antibodies. Last we have IgDs. These are going to be found on the surface of B cells, so they're actually just a receptor on B cells. So they play a major role in the sensitization of B cells. So hopefully remember your immune system is dominated by your B cells and T cells. B cells are the ones that control humoral immunity and IgD antibodies play a major role in sensitizing those B cells. So okay, those are your five classes of antibodies, Gamed G-A-M-E-D and that should get you ready to go. All right, have a wonderful day. Be blessed.