In this section we will talk about some basic concepts so that you can proceed to the comic with an understanding of what’s going on, and we will provide a brief summary of the themes that have been dealt with so far.
The Campaign Map
When we speak about the immune system, many times we think about a type of army that defends us against the diseases, tumors, et cetera which attack us every day. It is a constant battle!
Of course, every good battle comes with a campaign map, which you can find below.
- There are some organs that function as if they were military academies, where the cells of our army are produced and trained up, and where they mature. Examples of these are the bone marrow and thymus.
- Other organs act as barracks, where the troops are gathered and remain on alert until danger is detected. Some examples of these are the lymph nodes, found throughout the body, and the spleen.
- Obviously, there are troops who patrol those zones which are especially exposed to danger. These zones are the blood, skin, lungs, intestinal tract and the genitourinary system.
And who are the protagonists of these epic battles? The immune system is made up of many different components which can be classified according to the manner seen in the table above. This classification system is more theoretical than real, especially given that the protagonists constantly interact with one another. All the processes we are going to be seeing in this blog can happen at the same time, although occasionally some dominate the action.
Below we will show you some of the concepts we have been dealing with during the course of this blog:
All the cells of the immune system are born in the bone marrow, and, although they look nothing like one another, all come from the same cell — the haematopoietic stem cell. We will see some of the ups and downs of lympho family life in Episode 2.
As we shall see in Episode 3 “Lunch Time”, depending on the signals received by the precursor cells of the immune system, cells can grow, divide, mature or differentiate into one cell type or another. These signalling molecules, which the immune system uses for communications, are called cytokines.
Innate vs Adaptive Immune System:
Not all cells of the immune system are fully functioning following their birth in the bone marrow. While cells such as NK Cells or Granulocytes are immediately able to leave the bone marrow and fight the enemy (these form part of the innate immune system), there are others such as B- or T-lymphocytes that need a long period of education or training before they are battle-ready (these form part of the adaptive immune system). We will see some gut-wrenching examples of this in Episodes 4 and 5.
The Maturation of B-Lymphocytes
B-lymphocytes suffer the harshest of educations in the bone marrow. In this school of hard knocks they learn to tell the difference between elements of the body and those belonging to possible threats. B-cells that don’t cut the mustard (low affectivity, defective, self-reactive) are eliminated! We shall see this in Episodes 6, 7, 14, 15, 16, 17, 18 and 19.
The Maturation of T-Lymphocytes:
T-lymphocytes leave the bone marrow for the thymus, where they undergo an extreme training regime, which only a handful survives. In this manner, mature T-cells that mistakenly attack the body are removed, while only those that specifically target threats to the body are kept. In the “Diary of Tim O’Site” (Episodes 7, 8 , 9, 10, 11, 12 and 13) we will see how they train up a T-lymphocyte.