By Bernadine Rodrigo What everyone wishes to be and sometimes fancies themselves as being, especially at times like this when the looming threat of a fast-spreading virus is present, is completely immune to all illness. We often find ourselves under the weather and unable to engage in our daily activities and can always observe others around us suffering in the same way. Sometimes, these illnesses can come in ways of a simple cold, and at other times, fever and sometimes as life-threatening diseases. One thing that’s clear is that one cannot be 100% immune. Immunity is maintained in such as way that it doesn’t always protect someone from an illness but rather exposes someone to the illness, teaches that person’s body how to overcome the illness, and then guards the body from that illness subsequently. This action of learning through pain is done by the body’s immune system, indeed a truly unique system in the body. Unlike the other systems found within the human organism such as the nervous system or the digestive system, it is not something that can be demonstrated during an anatomy lesson with distinct parts, but one that is more in its primary form – the cellular form. The immune system of the human body exists in the bloodstream in the form of what we call white blood cells. As University of Colombo lecturer Dr. Sumudu Surandee, MBBS (Col) DipMicro (Col) MD Med Micro (Col), confirmed, these white blood cells are divided into two types. While white blood cells are known as leukocytes, the two types are known as phagocytes and lymphocytes. Both these types of white blood cells develop in the bone marrow and then spread around the rest of the body. Phagocytes are involved in the process of phagocytosis, which is the engulfment of antigens (what we call bacteria and viruses) in order to destroy them after alienating them from the rest of the cells in the body. Lymphocytes work in a little more of a technical way. Firstly, lymphocytes are of two types too, as shown by Dr. Suranadee. They are called B lymphocytes and T lymphocytes. B lymphocytes are those that understand the situation, so to speak. They try to identify if a specific cell is part of the body it belongs to or whether it is an alien cell such as a bacteria or virus. Bacteria and viruses have a different kind of indicator to what’s found in normal cells that the B lymphocytes are used to. These indicators are known as antigens. They are a small antenna-like structures which pop out of the cell. If the B lymphocyte cannot recognise it, then it begins signalling its colleagues – T lymphocytes – to come into action. T lymphocytes have a variety of ways through which they deal which these alien bodies. Sometimes, a bunch of them get together and surround the antigen-carrying body and punch holes around the cell so that it would explode and become unable to function; other times, it may signal nearby phagocytes to perform phagocytosis on these cells. Meanwhile, as the battle goes on between the T lymphocytes and the antigens, the B lymphocytes create a memory in the form of an “antibody”, which is something that pops up on the side of the cell complementary to the antigen. As each antibody is specific to the antigen it is inspired by, it also maintains a memory of how to get the body – or rather, the immune system – to function when faced with it. Hence, if the bacteria or virus with the same antigens infects the body again, the immune system knows exactly how to act. However, the unfair thing is that no matter how hard these lymphocytes and phagocytes work, there are always a few eminent disadvantages to them. One thing is, for these memories to be created by the B lymphocytes, the body must certainly be infected. This is why vaccines are given, explained Dr. Suranadee, so that the body will already be exposed to a milder form the bacteria or virus and gain the knowledge it needs to protect the body. It is always better to have this done at a young age so that these antibodies will only continue to grow as the person grows. “Some natural infection gives lifelong immunity. For example, measles, but some don’t,” she said. “Following vaccination, in most of the cases, we can maintain long-term, good immunity.” Another unfavourable factor is that it takes time for antibodies to develop even after being infected. Hence, the individual will certainly become ill and will have to suffer through their pain until the T lymphocytes are fully done with their task. Another terrifying fact is that viruses and bacteria are constantly mutating and finding better ways to compete with other organisms and hence, sometimes, they are capable of changing the antigen and re-infecting the body which can leave the body helpless and having to start the whole process all over again. Viruses mutate much faster than bacteria, and so they are more likely to return faster in that manner. The sad thing is that immunity is not something which can be developed. Either one is born with a fast-working immune system or an immune system that takes little bit more time to get its job done. However, there are ways through which one can make sure that the immune system stays as it is and doesn’t grow weaker and weaker. As Dr. Suranadee said, this can only be done through the basic methods of staying healthy. Malnutrition and various immune system disorders are the factors which hinder immunity, she said. Hence, it is important to take note that as one’s immune system is not some magical device which can shield you from all kinds of illness, you must try as much as possible to keep you body healthy in the ways you know you can.