Review of Cytotoxic vs Helper T Cells - Video Tutorials & Practice Problems

Review of Cytotoxic vs Helper T Cells

In this video, we're going to briefly review the differences between cytotoxic and helper T cells. And we're gonna do that by completing all of the interactive blanks in this table down below. And so notice on the far left, we have a column that says type of T cell. And recall there are two main types of T cells. The first are the cytotoxic T cells or TC cells for short. And the second are the helper T cells or the TH cells for short. Now notice that this entire row right here applies to cytotoxic T cells and this entire row down below applies to the helper T cells. Now recall that in terms of the CD marker, cytotoxic T cells have a CD eight marker on their surface. And so that's why cytotoxic T cells are sometimes referred to as CD eight cells. Whereas helper T cells have a CD four marker on their surface and they're referred to as CD four cells occasionally. Now, in terms of the antigen presenting proteins, recall that cytotoxic T cells are capable of recognizing and responding to antigens presented on MH C class one molecules and uh on the other hand helper T cells are capable of recognizing and responding to antigens presented on MH C class two molecules. Now recall that the Mh C class one molecules are going to be found on all nucleated cells. And this is partially what allows for cytotoxic T cells to target all of our nucleated cells. Now, on the other hand, Mh C class two molecules are not found on all nucleated cells. Instead, they're only found on some of our cells. Specifically the antigen presenting cells such as dendritic cells, macrophages and B cells. Now, in terms of the antigen source, notice that Mh C class one molecules are going to be presenting endogenous antigens or in other words, antigens that are inside the target cell. So for example, antigens from a virus that it's uh infecting the inside of a target cell. Now, Mh C class two molecules. On the other hand, they present exogenous antigens or antigens that are going to be outside of the target cell initially. And so you can see here, these antigens originated from outside of the target cell. Now they can be internalized and uh processed and then presented on these uh MH C class two molecules. But again, these antigens would have originated and be causing harm on the outside of cells. And uh notice that in terms of the target cells that once again, because MH C class one molecules are on all nucleated cells. It allows cytotoxic T cells to pretty much target any of our nucleated cells, which is practically all of our cells. Now, on the other hand, Mh C class two molecules are only found on those A P CS antigen presenting cells. And it turns out that the helper T cells, they mainly are going to be targeting the A P CS that include B cells and macrophages. And um in terms of the functions recall that cytotoxic T cells, their function is to induce target cell apoptosis, inducing apoptosis of infected host cells causing a cell that is infected with an intracellular pathogen, like a virus to undergo apoptosis in order to eliminate the infected cell, but also eliminate the pathogen, the intracellular pathogen. Now helper T cells. On the other hand, they do not induce apoptosis. Instead, they're all about activating or stimulating a target cell to improve that target cells, immune capabilities. And so they can target B cells and target macrophages to help activate those B cells and macrophages. And again, uh either lead to an immune response or lead to an improved immune response. And so this year concludes our brief review of cytotoxic versus helper T cells. And again, we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.

Comic Strip for Effects of T Cell Functions

In this video, we're going to briefly cover our comic strip for T cell functions. And so notice that down below, we have this portion of our image that corresponds to the same comic strip that we covered in our previous lesson video. And so here in this image, we've only added this little section over here. And this section here in pink is what is new in this video. And so just to refresh our memories about this comic recall that uh T lymphocytes will not be activated if harmless antigens are being presented. And so notice that our dendritic cell over here is presenting an antigen that is harmless. It's little stew which is a self cell, a harmless antigen. And so notice that the T cell here recognizes that this is a harmless antigen that there's no need to activate. And so it remains in an allergic or unresponsive state. And so it will not generate an immune response towards harmless antigens. Now, on the other hand, if a harmful antigen is being presented such as virus vic right here, then the dendritic cell is going to produce cos stimulatory molecules that will activate the uh T lymphocytes. And so notice he's saying here he is harmful and because this is a harmful antigen, it is going to be uh generating an immune response. So it activates reinforcements. And ultimately, in our new part of the image, the activated T lymphocytes are gonna be able to create a an effective immune response to ultimately eliminate the threat. Uh And so by eliminating the threat here, what you can see is that these other immune components have been assembled here, we have the CD eight cells, we have the CD four cells and uh the CD four cells can uh you know, activate macrophages and B cells and things of those nature to generate a, an effective immune response to eliminate the pathogen and destroy the pathogen so that it no longer is effective and cannot cause us harm. Now, as we'll talk about more moving forward in our course, we're going to learn how sometimes our immune system can cause unintentional harm to our own self. And so that is not a good thing about our immune system. Yes, it's very effective at eliminating pathogens, but occasionally it can uh cause our own tissues harm. And so we'll be able to talk about that aspect of our immune system more as we move forward in our course. But for now, what you can see here is that again, t lymphocytes are not activated with harmless antigens, they're activated with harmful antigens. And once those T lymphocytes are activated, they will work to eliminate the threat. And so we'll be able to get some practice applying these concepts and learn more as we move forward in our course. So I'll see you all in our next video.

Helper T cells respond to antigens from _____ and cytotoxic T cells respond to antigens from _____.

• A. Macrophages; B cells.
• B. Class II MHC; class I MHC.
• C. Viruses; bacteria.
• D. Class I MHC; class II MHC.

Which of the following cells is capable of specifically responding to a nearly infinite number of epitopes?

• A. B and T cells.
• B. Plasma cells.
• C. T cytotoxic cells.
• D. All of the above.