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Video transcript

Voiceover: Now we’re going to talk about chronic leukemias, and chronic leukemias come from these cells over here. Just like we did with the acute leukemias we can split up the chronic leukemias into chronic lymphoid leukemias and chronic myeloid leukemias. We’re actually going to start off by talking about the chronic lymphoid leukemias. We’re going to start off the chronic lymphoid leukemia which is usually just abbreviated CLL. Even though the name doesn’t tell you this CLL is a B-cell leukemia, so it comes from B-cell. CLL develops from this cell over here, so I’m just going to circle that and you can see from this diagram that the CLL cell is sandwiched in between the B-lymphoblast and the B-lymphocyte. It kind of exists in this fuzzy area, this gray zone in between the immature cell and the mature cell, and because of that it has certain characteristics that are more similar to the immature cell, and it has other characteristics that make it more similar to the mature cell. For example in terms of the appearance, how the CLL cell looks it actually looks pretty similar to a mature B-cell. If you were to look at a CLL cell it looks pretty much the same as a mature B-cell. Now something that you couldn’t tell just by looking at the cell is that a CLL cell is actually not as structurally strong as a mature B-cell. It’s weaker it’s more fragile, and if you took for example, if you took a drop of blood from somebody, from a patient who has CLL and you wanted to look at that drop of blood underneath a microscope you would then place that drop of blood onto a microscope slide, and you’d do some preparations and then you’d stick it underneath a microscope. Well that whole process of putting the cells the blood cells onto the slide causes the fragile CLL cells to rupture. That’s how fragile they are, they’ll rupture, and those ruptured CLL cells are called smudge cells. It’s pretty cool because if you didn’t know that the patient has CLL leukemia just by taking a look at drop of their blood if you were to see smudge cells that would kind of hint you in the direction of a CLL diagnosis. Okay, so that’s the appearance of these cells. Well, what about where these cells go to, where they live? A normal B-cell a normal healthy mature B-cell after it’s released from the bone marrow into the blood it will travel to three organs. It’ll go to the lymph node, the liver and the spleen, and it’ll go to these three organs. It’ll hang out over there and mature a little bit more, and it’ll wait for pathogens like bacteria and viruses to show up. When they do the B-cells will activate and they’ll attack the pathogens. That’s the job of the B-cells right? It turns out that in this regard our CLL cells are also mature enough to home to these same sites. The CLL cells also go to the lymph node, liver and spleen after they’re released from the bone marrow. Now, let’s think about that for a second. In CLL we have a cancer, we have a leukemia cancer of the lymphoid cells. If all of those lymphoid cells are going to these three organs what’s going to happen to the organs? They’re going to get bigger right, and you see that most significantly with the lymph nodes where after the CLL cells will go to the lymph nodes they’ll cause a generalized, meaning throughout the body, generalized meaning throughout the body, lymphadenopathy. So, it’ll cause a generalized enlargement of the lymph nodes throughout the body okay, and that has a special name. Why it has a special name I don’t know, but it has a special name. If a lymph node is enlarged in a patient who has CLL you can assume that that lymph node is enlarged because it’s filled with CLL cells and that lymph node will be called a small lymphocytic lymphoma. Oma means mass, and lymph refers to the fact that these are lymphoid cells, so it’s talking about a small mass of lymphoid or small mass of CLL cells okay? This brings us to a really important point, after these CLL cells traveled to the lymph node, and they start to take up more space inside there these cells can then acquire additional mutations that cause them to grow more quickly, more rapidly, and more out of control. Mutations that make these cells stickier for one another and the result of that is that these cells then form a genuine a true mass. That is referred to as a diffuse b-cell lymphoma, and that process by which this occurs is called a Richter transformation. In a patient who has CLL you may see generalized enlargement of the lymph nodes throughout the body, and after some time you may see that one lymph node in particular starts getting very big. That usually signifies that that inside that lymph node there’s been a transformation to a diffuse B-cell lymphoma. Now, let’s move on to the function of the CLL cells. Are they more mature or more immature in terms of their function? Well, what’s a function of normal B-cells? Usually one of the most important functions of a B-cell is to make antibodies right? In regards to making antibodies these CLL cells they fall short, they don’t do a very good job at all, and because of that in patients who have CLL you see a decrease in the number of antibodies in the blood. So you see a hypo, hypo meaning too few, gamma globulin, you may of heard of immunoglobulin or gamma globulin being different words to use to refer to antibodies, emia meaning in the blood. So, hypogammaglobulinemia, meaning too few antibodies in the blood, and that’s because the CLL cells do a very poor job of making good antibodies, but that doesn’t mean these cells don’t try. In fact, they try pretty hard they actually try to make antibodies, but unfortunately when they do make antibodies they do such a bad job that instead of the antibodies attacking bacteria and viruses and parasites, the antibodies start attacking our own cells. Specifically they start attacking our red blood cells causing them to rupture and die, and that’s referred to as an auto, auto means self, immune, so an immune response that is attacking our own body, hemolytic anemia okay? So we see a hemolytic anemia or a destructive anemia, red blood cells being destroyed because of an immune response attacking our own red blood cells. Now, that’s pretty much CLL in a nutshell. There’s another type of chronic lymphoid leukemia that develops from a B-cell and it’s called a hairy cell leukemia, and there are other chronic lymphoid leukemias that develop from T-cells. Specifically there’s adult T-cell leukemia, and there’s mycosis fungoides. I’m not going to go into much depth about them, but it’s always good to know that they do exist, but CLL when it comes to chronic lymphoid leukemia CLL really is where the money is at in terms of what you need to know.