How Do The Cells in The Immune System Work Together?
The immune system is like an army defending a castle. You can think of the immune system as an army defending a castle from invaders. The castle itself is a very important part of our immune defence; in this case “the castle” is our skin, and the mucus lining on the mouth, gut, nose and lungs.
There are several types of white blood cells that have specialised in different ways to fight infection:
Some cells act like foot soldiers or infantry; there are lots of them, they deploy rapidly so they are the first cells to arrive at an infection, but they don’t target or control the immune response. Some kinds of white cells that behave like this are so-called natural killer cells, neutrophils and granulocytes.
The sergeants of the immune system are cells like monocytes and macrophages. There are fewer of these cells, but they play an important role in controlling the immune response at the battlefront. Some macrophages turn into cells called dendritic cells; these are like the spies of the immune system. They collect information about the infection or abnormal cells and show this to other immune cells to inform them of the threat.
The most specialized cells of the immune system are lymphocytes. Lymphocytes are rare in the blood but important at the site of infection or in cancers, where they help specifically identify the target for the immune system to destroy. Lymphocytes use two different tools to identify target:
B-lymphocytes are like archers. They produce antibodies, small proteins that float around the entire body that very specifically recognise a particular kind of infection or abnormal cell. When an antibody sticks to a target, it acts like a flag and attracts the attention of other immune cells that then destroy the abnormal cell or bacteria. Vaccines work by instructing B-ymphocytes to make antibodies against a particular bug or virus. These are so specific however, that even small changes in the bug or the abnormal cell mean that the antibody doesn’t work. For example this is why you need to take a new flu shot every year; as the influenza virus evolves and changes, so to must we evolve and change the vaccine to give us protection.
Different Types of Blood Cells of The Immune System
T-lymphocytes are the second kind of lymphocyte, and come in two super special groups; commanders and commandos. T-lymphocytes don’t make antibodies, rather they make a similar kind of protein that sticks to the outside of the T-lymphocyte that is then used like a flashlight to examine each cell that the T-cell comes in contact with. Some T-lymphocytes (CD4) act as commanders of the immune system. They tell the immune system when to attack and when to retreat. People suffering HIV/AIDS lose these CD4 T lymphocytes and so their entire immune system is affected. People with HIV/AIDS suffer many cancers, and amazingly, if we can treat the HIV/AIDS with anti-viral drugs and restore the CD4-T-lymphocytes, then these people can see their cancers be cured. The other kind of T-lymphocytes (CD8) are like commandos; when they recognise a target cell they deploy a range of weapons to directly kill the target. It is these CD8-T-lymphocytes that appear to be the most important cells for killing cancers.