Compare and contrast T-dependent and T-independent antigens.

Question

Accepted Answer

Hello, everyone. Let's take a look at the next question. Which of the following describes t independent antigens. A, they can cross-link multiple B cell receptors simultaneously. B their activation of B cells involves multiple steps. C they induce the production of wide varieties of antibodies tailored to specific immune responses or D none of the above. So let's recall that normally, when we think of the activation of B cells, we know that we need the involvement of help or T cells. So, antigens that follow this process are the dependent antigens. They depend on helper T cells for that full activation of the B cells. And that's of course, after antigen binding onto the specific receptor for that antigen on the B cell, but we also have tea independent antigens. And they actually, as you might guess from the name don't need a helper T cell. They can activate those B cells just on their own by their binding to the receptors. And how does this happen? It's because they bind to multiple receptors on the B cell surface and then cause them to cluster together and cross link them. And this crosslinking can actually generate a signal strong enough to activate the B cell without the help of the helper T cell. How does this happen? Then it combined to multiple receptors at once. It does this simultaneously. Because in general t independent antigens, they're typically polysaccharides that they can't be presented with MH C molecules the way most antigens can and they are composed of repeating units. And so since they have these identical little sub units, they will bind simultaneously to multi multiple receptors at once and again, that binding causes this crosslinking and will activate the B cells without any need for A T cell. So let's look at our answer. Choices here. Choice A, they can cross link multiple B cell receptors simultaneously. Well, that is our answer. It describes those t independent antigens. And since we have a true answer here, we can cross out choice d none of the above, then let's look at our other choices just to understand why they're not correct. B their activation of B cells involves multiple steps. But we just saw that um the crosslinking and binding to multiple B cell receptors occurs simultaneously line that. So it doesn't need multiple steps. It just has one step. So the activation of B cells with multiple steps is the T dependent antigen process. There's about five steps, you have the um antigen recognition by the B cell receptors and then antigen processing until the um antigens being component is being presented by the MH C two molecules, the presentation of these antigens to T cells, then after the T cells bind T cell signaling to activate the B cell to differentiate and mature. So choice B multiple steps is the T dependent process. And the choice C, they induce the production of wide varieties of antibodies tailored to specific immune responses. This is also the T dependent process which allows a full range of antibodies to be produced in the tea independent process. It's not as powerful a process. You can see that this this whole procedure is a little bit rough and ready. And so only IgM class antibodies are generated and the protection generated by these is temporary, there's no memory cells generated. So that's why choice C is not our correct answer. So once again, the one statement here that describes T independent antigens as choice A, they can cross link multiple B cell receptors simultaneously. See you in the next video.

Compare and contrast T-dependent and T-independent antigens.

Verified Solution

Key Concepts

T-dependent Antigens

T-independent Antigens

Antibody Response