NCCN Guidelines for Patients® | Chronic Lymphocytic Leukemia

7 NCCN Guidelines for Patients ® : Chronic Lymphocytic Leukemia, 2019 1  CLL basics Blood You’ve learned that you have or may have leukemia. It’s common to feel shocked and confused. This chapter reviews some basics that may help you learn about chronic lymphocytic leukemia. Blood To learn about CLL ( c hronic l ymphocytic l eukemia), you first must know about blood. Blood is one of the fluids in the body. It consists of blood cells that move within plasma. Plasma is mostly water. Blood cells There are three main types of blood cells. One type is red blood cells (also called erythrocytes). Another type is white blood cells (leukocytes). The third type is platelets (thrombocytes). Blood cells have important jobs. Red blood cells carry oxygen throughout the body. White blood cells help fight germs. Platelets help control bleeding. Most blood cells are formed in bone marrow. Bone marrow is the sponge-like tissue in the center of most bones. Within marrow are blood stem cells from which all blood cells are formed. See Figure 1 . Stem cells make new cells that are a step closer to being a blood cell. These cells are called Figure 1 Blood cells Blood stem cells are the cells from which all blood cells are formed. They make two types of progenitor cells. Lymphoid progenitor cells form into white blood cells called lymphocytes. Common myeloid progenitor cells form into red blood cells, platelets, and white blood cells called granulocytes. Blood stem cell Myeloid progenitor cell Lymphoid progenitor cell Erythroblast Megakaryoblast Myeloblast Granulocyte Red blood cell Platelet Lymphoblast Lymphocyte Illustration Copyright © 2019 National Comprehensive Cancer Network ® (NCCN ® ).