Coordination among cells in a body is essential, both during development and in adulthood. Otherwise, a body simply could not grow and function properly.
B cells are white blood cells. B cells are part of the body’s adaptive immune system: the division of the defense system that remembers infections, and so can respond more rapidly if there is another attempted invasion. All vertebrates have an adaptive immune system with B cells. (Invertebrates also have adaptive immune systems, but they don’t use B cells.)
There are several types of B cells. Some help identify infected cells. Others playing distinct roles in different parts of the body. A certain type of B cell proliferates once an infection is found, amassing an army to help fight the onslaught. Some B cells are historians: remembering past wars and passing that knowledge onto the next generation.
While all B cells originate from stem cells in bone marrow, cells face divergent fates, placing them in different roles. B-cell fates must be balanced, so that there is no overabundance of some types and a shortage of others.
It was long assumed that the fate of a B cell was externally signaled, to harmonize production by type. Instead, B cells determine their own fates.
“External factors, such as hormones or cell signaling molecules, are not telling the cells what to do. Yet a reliable proportion of the B cells end up with each of the different fates.” ~ Irish immunologist Ken Duffy et al
How cell self-determination could result in balanced production within the body is physiologically inexplicable.