We just learned about the Epitope that the body looks at to find diseases.
Even though we've learned about all of the amazing things the human body does to fight off pathogens or diseases, sometimes the human body still gets sick.
Sometimes things go wrong with the blood cells we've learned about, with something called Blood Cancer.
Cancer is a disease that can affect any type of the body, from the bone to skin to brain.
Blood cancer has three different kinds: Leukemia, lymphoma, myeloma.
One of the ways that people test for these diseases is counting the number of each of the types of blood cells, from leukoctyes to lymphocytes to B cells.
The human body is supposed to have a certain number of each type of cells, and if the count is wrong then it can tell doctors something is wrong.
(from: wikipedia - tumors of the hematopoietic and lymphoid tissues)
Kid Facts - Blast from the past: Field of View