 Welcome back to our meds smarter lecture series where we're taking a smarter approach to preparing future physician Before we get started if you'll take just a quick minute and click that like button and also Subscribe and turn the bell on so that you'll be notified when we post new videos Let's continue our discussion of lymphoid structures by discussing regulatory T cells now What is the function of regulatory T cells? Well, they help to maintain specific immune tolerance by suppressing our CD4 and CD8 T cell effector functions Okay, how do we identify them? Well, we can test them for the presence of CD3 CD4 CD25 and the Fox P3 expression All right activated regulatory T cells also known as T regs will produce anti-inflammatory cytokines And some examples of those inflammatory Anti-inflammatory cytokines are gonna be your IL-10 and your TGF beta. All right, let's relate this to a syndrome specifically this syndrome is going to be IPEX Syndrome, okay, IPEX syndrome. So we're talking about immune dysregulation for the eye P is polyendocrinopathy. Okay, there's the P the E is Interopathy and then the X is X-linked. So IPEX syndrome IPEX is immune dysregulation polyendocrinopathy Interopathy and X-linked these are a genetic deficiency of the Fox P3 and if you remember up here that is identifying the regulatory T cells so they're identified by that expression and What that does is it conveys us a sense of autoimmunity. Okay, so People with the IPEX syndrome have interopathy endocrinopathy Nailed dystrophy is going to be another one That you'll see in these patients dermatitis. You can also have other different types of autoimmune skin skin conditions and One particular note here is that especially in male infants. It's associated with diabetes All right, let's talk about how T cells and B cells are activated and we're going to get to the specific Downstream effects here in a minute, but before we get to that, let's talk about a little bit of information that we'll need to know down the road What are APCs? APCs are B cells dendritic cells, Langerhans cells and macrophages and Beyond that we need two signals here to be able to activate our T cells or our B cells or to have class Switching occur so we can't just do this with one signal. There has to be two signals that occur for this to happen On the right side here, you can see Some of these activation and switch class switching that can go in here We're going to discuss that in the slide to come here. All right So let's talk about the process of T cell activation The first thing that happens for a T cell to become activated is you have to have dendritic cells or what we discussed earlier Some type of an APC or specialized APC cells that will go in they'll sample and process an antigen and they Migrate that antigen to a draining lymph node. So as you can see over here, this number one process is going to be that little blue thing that's going to intake that particular Antigen and digest it then it allows that to Move further down the road. So what's the next step? The next step is T cell activation So this is our first signal remember we talked a minute ago that you have to have two signals for activation to occur that first signal is the T cell activation where Exogenous antigen is presented on an MHC to receptor and That's recognized by the TCR on our T helper cells, which is a CD for cell Dageness or cross-presented antigen is presented to our MHC one using a CD eight cell remember our rule of eight a CD four is an MHC two because two times four and an MHC one is a CD eight because eight times one all equals eight So this specific step is occurring In this region over here on this particular picture beyond that point now We have to move to the proliferation and survival stage, which is our second signal For the T cell activation and this is a co-stimulatory Signal where we have B7 proteins, which are CD 80 CD 86 on a dendritic cell and CD 28 on a naive cell And this particular point is going to be occurring here on this picture and then finally here at the bottom of the photo the Final process in this T cell activation is we have activated T helper cells that can produce cytokines Those T cells are able to then recognize and kill any virus infected cell As you can see down here in the bottom if you found this material helpful for your studying Please like and consider subscribing to the channel also share this video so that more people can benefit from it like you have