In this video, we're going to talk more about B cell activation by T independent antigens. First, we need to recall from some of our previous lesson videos that unlike T dependent antigens, T independent antigens can actually activate naive B cells independent of helper T cells, or in other words, without helper T cells. Now, these T independent antigens are typically long polysaccharides with multiple closely spaced identical repeating subunits. Also, these T independent antigens typically do not initiate an immune response in very young children, which makes very young children and kids more susceptible to some pathogens that have these T independent antigens. The good thing is that these T independent antigens are not as common as T dependent antigens.
If we take a look at our image down below, we can get a better understanding of these T independent antigens. What you'll notice on the left-hand side of our image over here is our naive B cell in blue which of course is going to have its B cell receptors (BCRs) on its surface. Here in red, this long structure you see represents our T independent antigen. These T independent antigens are typically long polysaccharides with multiple closely spaced identical repeating subunits. That's what we see here, these multiple closely spaced identical repeating subunits throughout this entire T independent antigen. These T independent antigens are able to activate this naive B cell without a helper T cell. Notice that there is no helper T cell anywhere within this image. B cell activation can still occur with these T independent antigens.
The naive B cell, when it becomes activated, can proliferate or multiply and differentiate either into plasma cells that secrete antibodies or memory B cells that are important for protecting upon a future infection. The key here is that T dependent antigens require helper T cells, whereas T independent antigens do not require helper T cells to activate a B cell. This here concludes our brief lesson on B cell activation by T independent antigens, and we'll be able to get some practice applying these concepts moving forward. I'll see you all in our next video.