In this video, we're going to continue our introduction to B lymphocytes by talking about the ability for naive B cells to become effector plasma cells and memory B cells. First, what we need to know is that before a B cell encounters a free antigen, that B cell exists in an inactive form that we refer to as a naive B cell. Once again, a naive B cell is really just an inactive B cell that has not yet encountered its free antigen. Now, upon encountering its free antigen and then presenting that free antigen on an MHC class 2 molecule, the naive B cells are going to be bound and activated by helper T cells. Recall from our previous lesson videos that helper T cells can help to activate B cells. These activated B cells are capable of proliferating or multiplying to create identical clones of itself, as well as differentiating or changing its phenotype to become either an effector plasma cell or a memory B cell.
The effector plasma cells are going to be short-lived cells that make antibodies. They can make thousands of antibodies per second, so they're making lots and lots of antibodies. These antibodies, as we'll learn moving forward in our course, are capable of immediately responding to the first infection. They are able to respond to the infection in many different ways. The memory B cells, on the other hand, are long-lived cells and do not respond immediately to the first infection. Instead, these memory B cells are long-lived cells, they somewhat remember the antigen, and they help eliminate that future infection even faster than the primary infection was eliminated.
If we take a look at our image down below, we can get a better understanding of the ability for the naive B cell to differentiate into either an effector plasma cell or a memory B cell. Notice over here on the left-hand side what we have is a naive B cell, an inactive B cell. And when this naive B cell encounters a free antigen, as you see right here, a free-floating antigen that's not being presented, this free antigen can be internalized into the B cell, processed, and then presented on MHC class 2 molecules. The MHC class 2 molecules are going to allow helper T cells to activate the naive B cell. The activation of the naive B cell will allow the naive B cell to differentiate either into a memory B cell as we see right here, or it would allow the B cell to differentiate into a plasma cell. And the plasma cell would be the effector cell, again capable of releasing and producing thousands of antibodies per second, releasing those antibodies into the environment, and those antibodies that are released into the environment can then carry out several different immune responses, which again we'll get to talk about as we move forward in our course.
Again, recall that on these B cells they have these B cell receptors or BCRs. The BCRs that a B cell has are pretty much membrane-embedded versions of the antibodies that that B cell ends up producing after it differentiates into a plasma cell. This here concludes our brief lesson on how naive B cells can become effector plasma cells and memory cells. Once again, 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.