Classes of Antibodies - Video Tutorials & Practice Problems
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1
concept
Classes of Antibodies
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Video transcript
In this video, we're going to talk about the different antibody classes and so it turns out that there's actually 5 different classes of antibodies or in other words, 5 different classes of immunoglobulins. And so these five classes are based on differences in their heavy chains as we'll see down below in our table. And so the 5 classes of antibodies are I IgG, IgA, IgM, IgE, and IgD. And if you look at these red letters here, notice that it spells gamed, and so notice down below right here we have this antibody stick figure playing some video games, and based on his facial expression, I'd say he's pretty gamed out from playing video games for 72 hours straight. And so hopefully this antibody stick figure along with GAMED will help you guys remember the 5 different classes of antibodies. And so looking at this table right here, what I want you guys to notice is that, the light chain for all 5 classes of antibodies is exactly the same. So the light chain Y, there'd be the one that's Greek letter lambda. And so the light chain is not going to distinguish 1 antibody class from another. However, looking at the heavy chain, notice that each class of antibody has a unique heavy chain. And so it's the heavy chain that's going to distinguish 1 antibody from, one antibody class from another. And so this first row of, antibody, this first class of antibody is IgG and this is really the one that we've been talking about all along and so you can see the y shaped structure here that we talked about. Now, notice that IgE and IgD have very similar type of structures to IgG. However, IgA forms a dimer of these 2 y shaped structures and IgM tends to form a pentamer, containing 5 different y shaped structures here. Now, over here in this column, what we have is the primary feature of each of these antibodies. Now, IgG is actually the most prevalent and the most abundant antibody in our blood. So this is going to be one that's involved, in protecting pretty much against all types of infections including bacterial and viral infections. Now, IgA is actually going to be highly concentrated in mucus membranes and it's going to be one that is, typically secreted by our cells and, it's also prevalent in our saliva. Now, IgM interestingly enough is usually going to be the first antibody, that's going to be produced upon infection. So, IgM is going to be the one that's going to initiate the primary immune response. So the very first immune response. And then, the common second immune response would be IgG since it's so prevalent in our blood. Now IgE on the other hand here is gonna be one that's gonna defend against allergies or allergens. And so you can see here we have a guy who's saying I'm allergic to this kitty cat right here, and that's unfortunate because this is a cute little kitty cat. But IgE again is going to help defend against these allergens. Now IgD is one where its function is not really very well characterized. However, there are some, textbooks and studies that say they're involved with activating b cells and, allowing b cells to, participate in immune responses. Now over here on the far right, what we have is the distribution of these antibodies, classes throughout our bodies. And so notice that pretty much all of the antibodies are gonna be found in our bloodstreams, except for IGA, which again is gonna be highly concentrated in our mucus membrane. So it's gonna be lining our, digestive systems a lot. And so this here concludes our introduction to the antibody classes and we'll be able to talk more about antibodies as we move along in our course. So, I'll see you guys in our next video.
2
Problem
Problem
Which of the following is NOT an immunoglobin class?
A
IgM.
B
IgH.
C
IgG.
D
IgE.
E
IgD.
3
concept
IgG
Video duration:
3m
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Video transcript
In this video, we're going to talk more details about the IgG class of antibody. And so the IgG antibody is the standard antibody. And that is because the IgG antibodies are the most abundant antibody class in our blood and in our tissues. And in some individuals, the IgG antibodies can make up to 80% of all of the immunoglobulins. Now these IgG antibodies can have a variety of different functions. However, they are capable of binding to very specific antigens, and they can eliminate pathogens by activating the complement system classical pathway, which recall we covered the complement system classical pathway in our previous lesson videos when we discussed innate immunity. Now IgG antibodies are also well known for providing immunity to a developing fetus during pregnancy, as well as providing immunity to a newborn child after the child has been born. And so this is because these IgG antibodies have the amazing ability to cross the placenta between a mother and the baby. And so the mother's IgG antibodies are capable of crossing the placenta to protect the baby. So literally the mother is protecting the baby with her antibodies. Now also IgG antibodies are well known for having a long half life. And all that means is that, if it has a long half life, is that it's very very stable, and it is capable of lasting a long time within our bodies before it's broken down. And so this long half life actually extends the time of protection of a newborn, through the first few months after birth until the baby is capable of generating its own antibodies. And so basically what we're saying here is that literally a mother's antibodies protects the baby as the baby is a developing fetus, and for the first few months of the baby's life until the baby's capable of generating its own antibodies. And so if we take a look at our image down below, it's just an image emphasizing those important features of the IgG class of antibody. And so notice that its structure is gonna be that standard antibody structure that we talked about in our previous lesson videos. Notice it is the most abundant class of antibodies. Around 80% of the antibodies are gonna be IgG. It provides infant immunity during, again, pregnancy, as well as after childbirth as well because the IgG antibody has that amazing ability to cross the placenta between the mother and baby. And last but not least, this IgG antibody has many different immune functions including the ability to activate the complement system via the classical pathway where it can bind to antigens. And again, you can see activating c 3 convertase leading to many different types of complement system, activities such as inflammation, optimization, cell lysis of microbes, and so on. And again, if you don't remember these details here about the complement system classical pathway, be sure to go check out our older lesson videos on that content. But for now, this here concludes our brief lesson on the IgG class of antibodies and as we move forward in our course we'll also be able to discuss briefly some of the other classes of antibodies. So I'll see you all in our next video.
4
concept
IgA
Video duration:
2m
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Video transcript
In this video, we're going to briefly discuss the IgA class of antibody. And so the IgA class of antibody is going to help protect mucus membranes throughout our bodies. And they can also be found in body secretions such as for example, saliva, tears, and breast milk. Now the IgA antibody is commonly found as a dimer, which means that it consists of 2 identical subunits that are held together. And this dimer is referred to as secretory IgA or s I g a for short. And within this secretory IgA molecule, which is a dimer, it consists of 2 monomers that are held together by a peptide, and we'll be able to see that down below in our image. Now the secretory IgA antibody in breast milk helps protect the intestinal tract of breastfed newborns which is why breastfeeding can actually be very healthy for newborn babies to provide them with those IgA antibodies that can help protect, again, the intestinal tract of those newborns. And so if we take a look at our image down below, we're just emphasizing those same important details of the IgA antibody. And, again, the IgA antibody is commonly found as a dimer that we refer to as secretory IgA. And so what you can see here is that there is a dimer. There's, this unit right here and then there's this, other identical unit right here. And these two units are held together by this blue peptide that is swirling around it. And so, that is the secretory IgA antibody. Again this is really going to be important for protecting mucus membranes, throughout our bodies And also it's gonna be found in, mucus, saliva, tears, and breast milk. And so you can see those images down below. And again because it is found in breast milk it will help protect the intestinal tract of newborn babies that are breastfed. And so you can see the IgA antibody here dissolved within this breast milk. And so, this here concludes our brief lesson on the IgA class of antibody, And again we'll be able to get some practice applying these concepts and talk about the other classes of antibodies briefly as we move forward. So I'll see you all in our next video.
5
concept
IgM
Video duration:
3m
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Video transcript
In this video we're going to briefly discuss the IgM class of antibody. And so the IgM antibody is very important for controlling infections in the blood. And it is actually the very first antibody that is going to be initially produced in a primary infection by plasma cells before a process known as class switching takes place. And later in our course in a different video we'll talk more about this antibody class switching. Now the IgM class of antibody is also the largest class of antibody in terms of its size and molecular mass, because IgM antibodies consist of a pentamer, which means that it is composed of 5 identical y shaped subunits. And because it has 5 y shaped subunits, each subunit with 2 antigen binding sites, that means that there are 10 antigen binding sites. And because there are so many antigen binding sites on these IgM antibodies, that makes them very, very effective at linking antigens together. Now the large size of the IgM antibody class actually prevents the IgM antibody from leaving the blood, into the tissues. And so that's why the IgM antibody, its primary role is to help control infections in the blood. Also, the IgM, class of antibody is the most efficient antibody class at activating the complement system via the classical pathway. And so if we take a look at our image down below, once again, we'll have an image that helps to emphasize those same features of the IgM class of antibody. Notice first that it is indeed a pentamer that consists of these five identical y shaped subunits. And so that makes it the largest antibody class. So we can label it here as the largest antibody class in size. Also, it is the very first antibody that is initially created by all plasma cells prior to the antibody class switching process that we'll get to talk about in more detail later in our course. And the primary role of the IgM antibody because of its large size is to control infections in the bloodstream. Also this is the most effective antibody at activating the complement system. So it activates the complement system when it binds to the antigen. And again, here we have a little image that shows you c three convertase being generated upon activation of the complement system and then all of these actions that result from the complement system activation including inflammation, optimization, and cell lysis of microbes. And again, if if you don't remember much about the complement system make sure to go back to our older lesson videos to check those out. But again this year concludes our brief lesson on the IGM class of antibody, and we'll be able to get some practice applying these concepts and talk about the other classes as we move forward. So I'll see you all in our next video.
6
concept
IgE
Video duration:
2m
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Video transcript
this video we're going to talk briefly about the IgE class of antibody. And so the IgE antibodies are found on the surface of both basophils and mast cells. And recall that basophils and mast cells are going to have a lot of similarities, but recall that basophils will circulate through the bloodstream, whereas mast cells are more localized within specific tissues. And so, when these IgE antibodies are on the surface of basophils and mast cells, they're capable of detecting and responding to very specific antigen. And these IgE antibodies can actually cause the cell to undergo a process called degranulation, which you might recall from some of our previous lesson videos just means that it will cause these cells to release their granules and the contents of their granules into the environment. And so, that can include releasing inflammatory mediators that lead to inflammation in response to some kind of infection. Now, these IgE antibodies are very important for eliminating parasites, such as worms, and they're also going to play an important role in the response to many different types of allergic reactions or hypersensitivities which we'll get to talk more about allergic reactions and hypersensitivities much later in our course in a separate video. But for now if we take a look at our image down below we can get a more solid understanding of this IgE class of antibody. And notice here it has that same antibody structure and again it's found on the surface of both basophils, as well as mast cells. And so you can see, the basophil over here, the mast cells over here, and upon binding their antigen, they cause degranulation, the release of the contents of the cytoplasmic gran these IgE antibodies are important for protecting against parasitic infections like, those parasitic worms as well as again responding to allergies or generating those allergic reactions. And again we'll get to talk more about allergies later in our course. But for now this here concludes our brief lesson on the IgE class of antibody and we'll be able to get some practice applying these concepts and then talk about the very last class of antibody. So I'll see you all in our next Video.
7
concept
IgD
Video duration:
1m
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Video transcript
In this video, we're going to talk very briefly about the IgD class of antibody. And so IgD antibodies are found on the surface of b cells, and they signal b cell activation and maturation into an antibody secreting plasma cell. And so really these IgD antibodies are important for the development and maturation of the antibody response. And so if we take a look at our image down below, we can see here that the IgD antibody is, again, a monomer that you can see here that makes up a very small percentage of all of the antibodies, about 1% of all the antibodies. And again, it's going to be found, it can be found on the surface of b cells, as you see here. And, their role on the surface of b cells is again to help, the b cell differentiate into plasma cells that can secrete antibodies. And so the IgD antibody is going to help activate the b cell and help it differentiate into a plasma cell. And, ultimately, the plasma cell will be able to secrete a variety or different types of antibodies. And so this here concludes our brief lesson on the IgD antibody and its role in the development and maturation of the antibody response, and we'll be able to get some practice applying this as we move forward. So I'll see you all in our next video.
8
Problem
Problem
______ is the first immunoglobulin class produced during a primary response.
A
IgA.
B
IgE.
C
IgM.
D
IgG.
9
Problem
Problem
Which antibody class crosses the placenta from mother to child?
A
IgA.
B
IgE.
C
IgM.
D
IgG.
10
Problem
Problem
_______ is the immunoglobulin class that neutralizes viruses in the intestinal tract.
A
IgG.
B
IgA.
C
IgD.
D
IgE.
11
Problem
Problem
Which of the following antibodies is involved in causing basophils to release histamine when the antibody encounters an allergen?
A
IgG.
B
IgA.
C
IgD.
D
IgE.
12
Problem
Problem
The primary B-cell receptor is:
A
IgD.
B
IgA.
C
IgE.
D
IgG.
13
concept
Review Table of Immunoglobin Classes
Video duration:
3m
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Video transcript
In this video, we're going to do a quick review of all of the immunoglobulin classes or all of the classes of antibodies. And so we're gonna do that by completing this review table of the immunoglobulin classes. And so, what you'll notice is that we have these five classes of antibodies arranged so that they fit our mnemonic, which is GAMED, And 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, 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 again, 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. And 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 s IgA antibody. Notice that its half life is medium and it's going to be important for protecting the mucus 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 and 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 half life is very 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. Now the IgD antibodies are gonna be found on the surface of b cells or can 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.
14
Problem
Problem
Each class of antibody is specifically defined by its
A
Amino acid sequence of the variable region of the light chain.
B
Amino acid sequence of the constant region of the heavy chain.
C
Ability to cross the placenta.
D
Disulfide bonds.
15
Problem
Problem
Match the following antibody classes with their description:
a) IgA. b) IgG. c) IgE. d) IgM. e) IgD.
___ First antibody produced during primary response.
___ Protects mucous membranes.
___ Most abundant antibody.
___ Found on the surface of B cells.
___ Triggers allergic reactions to allergens.
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3m
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