I would like to take you into a different world. I am no J.K. Rowling to create a fictitious world. The one we are going is real. Discovered a few centuries ago, this is an elusive world with impeccably arranged moieties which pose perpetual challenges to the understanding of their functions. There are times and places where these moieties exist in reconciliation; but many a times they are engaged in the battles fiercer than the battle of Kurukshetra or the World Wars I and II. There exist peace-keeping bodies like UNO but these battles are inevitable in the sense that they aren’t fought for greed or jealousy. These battles are fought for survival where there is absolutely no mercy for the timid.
I would not have taken you to this world if it were not for Ganaraj who insisted me to take him there. Though it wasn’t the first time I was visiting, with him I found it more vivid than before. The more I explained him, the more I learnt myself. I remember, my physics teacher (Mr. K. S. Murugesh Sir) used to tell us, “You should write your answers in such a way that even the last fool in the universe should understand physics by reading them.” Well, that’s the way I learnt physics. But now, I was asked to answer a biology question in that way…
Ganaraj asked me, “Why does one get fever?” It was 13th of February. “Well, it isn’t uncommon for a guy like you to get fever on the eve of Valentine’s!” I chuckled, not knowing that he was running a mild fever since some days. He is a techie who analyses the problems to depth before trying to fix them. And so, I had to explain him Immunology in a way I had never done before.
Just as a kingdom’s territory that has some natural barriers like mountains or river or sea at its boundary, the human body too has some natural barriers – viz. Skin (the largest organ in the body), Hydrochloric acid in the stomach that kills microbes in the contaminated foods, the hair and mucous in our nose that trap microbes in the contaminated air etc..
If the bugs somehow manage to cross these barriers and try to gain access into our body, the war begins. Most tissues have got cells called ‘Macrophages’ (literally meaning, ‘Big Eaters’) which function as scavengers. They keep ‘eating’ dead materials (from turnover of worn-out cells) and when they feel there’s some foreign material, they get alert and ‘blow the conch’ for the battle. The white blood cells (WBCs) are the soldiers that are constantly circulating in the blood stream. So, when the macrophages need help, they release ‘cytokines’ or ‘chemical messengers,’ that signal the circulating ‘soldiers’ (WBCs) to move into the place of battle; just as you dial 911 (or 100 in India) when you are in danger. One such cytokine is Interleukin-1 which alters the “temperature regulator” in the brain. It is like setting the ‘thermostat’ at a higher temperature and the body temperature goes up. That’s how Ganaraj was having fever! (So did we all!)
There are different types of WBCs, each of which is a ‘specialist’ in the use of different ‘weapons.’ First ‘Neutrophil’, a kind of WBC, visits the battlefield, makes a general survey and releases some more ‘chemical messengers’ to wake up the ‘sleeping soldiers’ and attack the enemy.
As I said earlier, this battle is going to be fierce and in battles it’s not just the invaders that die; thousands of soldiers and civilians too. To minimise as much damage as possible, the army works on sharpening the target. Once macrophages ‘gulp’ the invading microbe, they process it and the ‘key features’ (antigens) are documented and conveyed to the ‘soldiers’ so that they can distinguish the enemies from the civilians – the process is termed “Antigen Processing.” This is something like the FBI’s way of taking the photographs of the criminals and circulating them with a “Wanted” stamp. Once the enemy is identified (or the antigen is processed) it is taken to the Helper T-cells or the “Commander-in-chief” of the army. Helper T-cells or CD4+ T-cells are also a kind of WBCs. This is the prime target of the notorious virus HIV; HIV kills the commander-in-chief of the army, soldiers go helter-skelter and the army disintegrates. And so, the open door tempts even a saint!!
The commander-in-chief (Helper T-cell) coordinates between the other specialists of the army. It does so by means of ‘cytokines’ or chemical messengers. There are varieties of cytokines, each one carrying a specific message. It is like a Morse code. One specialist of the army is Cytotoxic T-cell, a kind of WBC, comparable to a ‘bombing expert.’ Once the Helper T-cell sensitises the Cytotoxic T-cell with the ‘photograph’ (antigen) of the enemy, it goes in search of the microbe and kills it. As I said, it does so with ‘bombs’ which claim the lives civilians as well!
The other specialist is a B-Lymphocyte or B-Cell, again a kind of WBC, comparable to a ‘missile expert.’ Again the commander-in-chief, Helper T-cell awakens the B-cell by showing the enemy’s photographs (antigens). B-cell generates antibodies (missiles) against the antigens. The antigen’s structure is assessed by the B-cell and the antibody it generates is complementary in structure to that of the antigen, so that the two fit exactly into each other; something like a lock-and-its-key or a box-and-its-lid or simply a USB-port-and-USB-connector! These missiles or the antibodies are released into the blood stream and wherever they encounter the microbe they fasten themselves to their respective antigens. With antibodies sticking on to them, the microbes become docile and thereupon they can easily be destroyed. Again scavengers (macrophages) come to site of destruction and ‘mop up’ the debris. Later on new cells deftly replace the lacunae.
That’s not the end of it all. Some of the ‘specialist’ cells remain quiescent. Not because they are sloths but because they are used as ‘Immunologic Memory.’ It is like adding a copy of the file to the database for future references. In due course of time, should the same microbe invade the body again, the ‘soldiers’ need not waste time in analysing the antigens. The memory cells form copies instantly and attack the bug more vigorously and efficiently. This amazing property of our immune system is the basis for Immunisation. Immunologists artificially process the bugs and present the antigens in the form of vaccine. The immune system gets acquainted with the bug’s antigens and forms ‘memory’ and whenever the infection with that bug occurs; it will be a cake walk for the ‘soldiers.’ The ‘boosters’ we receive every-once-in-five-years or so are meant to trigger our fading Immunologic ‘memory.’
What an immaculate mechanism! I had wondered. It may have taken millions of years of evolution but every day is worth it, I had felt, during the first year of my medical school. But if it were to be as perfect as I had imagined, I would not have to study the subjects in the later years of my medical school! Oh, yes, I mean it! As I moved on, I understood that despite such a composite organisation, things go wrong. I saw a few cases where the ‘Morse code’ was ‘misread’ and resulted in catastrophes beyond imagination. These are the Disorders of Immune System – autoimmune disorders, hypersensitivity (commonly referred to as ‘Allergies’) and Immunodeficiency disorders etc. I also saw the specimens in the pathology museum; sufferings in almost all the wards of the hospital because of bugs that somehow managed to delude the immune system.
No amount of complexity is sufficient. The bugs take it as a challenge and evolve into ‘stronger’ bugs. Antibiotics are no reason to open champagne. Bugs are amazingly brilliant in developing alternate biochemical pathways to elude the harmful chemicals. If we don’t struggle we lose the battle; and complacency is our greatest enemy. So, the quest for perfection continues… Who’s next?
