A person missing their spleen gets sick much more often than someone with a spleen. Bone marrow Bone marrow produces new blood cells, both red and white. In the case of red blood cells the cells are fully formed in the marrow and then enter the bloodstream. In the case of some white blood cells, the cells mature elsewhere. The marrow produces all blood cells from stem cells .
Stem cells change into actual, specific types of white blood cells.
White blood cells are described in detail in the next section. The binding generally disables the chemical action of the toxin. When an antibody binds to the outer coat of a virus particle or the cell wall of a bacterium it can stop their movement through cell walls. Or a large number of antibodies can bind to an invader and signal to the complement system that the invader needs to be removed. Whenever you see an abbreviation like IgE in a medical document, you now know that what they are talking about is an antibody.