As we know by now, all the cells of the immune system are generated in the bone marrow. Given that these cells carry out their functions in a large variety of tissues, the moment arrives when they must abandon what have been up to this point their homes in order to go in search of adventure in the big bad world that constitutes the body.
Some of these cells leave home pretty wet behind the ears, as is the case with T-lymphocytes, which have to travel to an organ called the thymus, which is located underneath the sternum. The thymus is something like military academy, where attack and support troops are trained.
Other cells, by the time they have left the bone marrow, have learned practically all the skills they need to carry out their tasks; take for example, granulocytes, who leave the bone marrow for the blood in search of far-flung destinations.
NK cells and macrophages undergo part of their maturation process in the bone marrow, but before finishing their training travel to other tissues where they complete their education.
The bone marrow is where we find Artillery Boot Camp, or Artillery Academy, and it is here that the last of this tissue’s rookies remain: the B-lymphocytes, whose maturation process is lengthier and more complex than other cells.
As you might imagine, the process you see above doesn’t happen just once, but is constantly underway, eternally generating new immune cells. So in reality, although our friend Johnny B. Goode feels abandoned by his friends, B-cells are never alone for long — there are always new recruits.
In the next few episodes we will show one by one the maturation processes for each cell type, the abilities these cells acquire, and under which circumstances each of them confronts the enemy.